JP3497430B2 - Spin valve thin film element and thin film magnetic head using the spin valve thin film element - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spin-valve type thin film element whose electric resistance changes depending on the relationship between the fixed magnetization direction of a fixed magnetic layer and the magnetization direction of a free magnetic layer affected by an external magnetic field. , A spin-valve thin-film element capable of dividing a pinned magnetic layer into two layers and keeping the magnetization (ferri state) of the two pinned magnetic layers in a thermally stable state, and the spin-valve thin-film element The thin film magnetic head.

[0002]

2. Description of the Related Art FIG. 28 is a sectional view showing the structure of a conventional spin-valve type thin film element as viewed from the side facing a recording medium.

Reference numeral 1 is an underlayer formed of, for example, Ta (tantalum), an antiferromagnetic layer 2 is formed on the underlayer 1, and a pinned magnetic layer is further formed on the antiferromagnetic layer 2. 3 is formed.

Since the pinned magnetic layer 3 is formed in contact with the antiferromagnetic layer 2, an exchange coupling magnetic field (exchange anisotropic magnetic field) is formed at the interface between the pinned magnetic layer 3 and the antiferromagnetic layer 2. Occurs, and the magnetization of the pinned magnetic layer is pinned, for example, in the Y direction in the figure.

A non-magnetic conductive layer 4 made of Cu or the like is formed on the fixed magnetic layer 3, and a free magnetic layer 5 is further formed on the non-magnetic conductive layer 4.
On both sides of the free magnetic layer 5, hard bias layers 6 made of, for example, a Co—Pt (cobalt-platinum) alloy are formed.
6 is formed, and the hard bias layers 6 and 6 are magnetized in the X direction in the figure, so that the free magnetic layer 5 is formed.
Are aligned in the X direction in the figure. As a result, the variable magnetization of the free magnetic layer 5 and the fixed magnetization of the fixed magnetic layer 3 cross each other. The reference numeral 7 is T
A protective layer formed of a or the like, reference numeral 8 is a conductive layer formed of Cu or the like.

In this spin-valve type thin film element, a leakage magnetic field from a recording medium such as a hard disk causes X in the drawing.
When the magnetization of the free magnetic layer 5 aligned in the direction changes, the electric resistance changes in relation to the fixed magnetization of the fixed magnetic layer 3 fixed in the Y direction shown in the drawing, and the voltage changes based on the change in the electric resistance value. Thus, the leakage magnetic field from the recording medium is detected.

[0007]

By the way, conventionally, as the antiferromagnetic layer 2, a NiMn alloy, a FeMn alloy,
Alternatively, an antiferromagnetic material such as NiO is used.

However, among these materials, FeMn
Alloys and NiO alloys have a blocking temperature of about 200 ° C. or lower and are materials lacking thermal stability. Particularly in recent years, the environmental temperature in the apparatus becomes high, for example, 200 ° C. or higher due to the number of rotations of the recording medium or the increase in the amount of sense current flowing from the conductive layer 8. Therefore, when an antiferromagnetic material having a low blocking temperature is used as the antiferromagnetic layer 2 of the spin-valve type thin film element, an exchange coupling magnetic field (exchange different magnetic field) generated at the interface between the antiferromagnetic layer 2 and the pinned magnetic layer 3 is used. The magnetic field of the fixed magnetic layer 3 cannot be properly fixed in the Y direction in the figure, and the ΔMR (rate of change in resistance) is lowered.

Since the blocking temperature is determined only by the antiferromagnetic material used for the antiferromagnetic layer 2, even if the structure of the spin valve thin film element is improved, the blocking temperature itself cannot be increased. Can not.

For example, Japanese Patent Laid-Open No. 9-16920 discloses that
The invention is described in which the structure of the pinned magnetic layer can be improved to enhance the exchange coupling magnetic field. But,
In this invention, since NiO is used as the antiferromagnetic layer, the blocking temperature is about 200 degrees, and even if the exchange coupling magnetic field at room temperature can be increased, the temperature inside the device is close to 200 degrees, Alternatively, when the ambient temperature is higher than that, the exchange coupling magnetic field of the spin-valve type thin film element during traveling of the recording medium becomes small or becomes 0, and ΔMR cannot be obtained at all.

On the other hand, NiMn alloys have NiO and F
Although the blocking temperature is higher than that of the eMn alloy, the antiferromagnetic material used as the antiferromagnetic layer has an even higher blocking temperature because of its poor corrosion resistance and other properties, and it also has excellent anticorrosion properties such as corrosion resistance. Magnetic materials are required.

The present invention is intended to solve the above-mentioned conventional problems, in particular, the structure of the pinned magnetic layer and the material of the antiferromagnetic layer are improved, and the pinned magnetic layer has a proper thickness. An object of the present invention is to provide a spin-valve thin-film element having excellent thermal stability and a thin-film magnetic head using the spin-valve thin-film element, which can be adjusted to increase the exchange coupling magnetic field.

[0013]

The present invention is directed to an antiferromagnetic layer and a pinned magnetic layer formed in contact with the antiferromagnetic layer and having a magnetization direction fixed by an exchange coupling magnetic field with the antiferromagnetic layer. And a free magnetic layer formed on the pinned magnetic layer via a non-magnetic conductive layer and having a magnetization aligned in a direction intersecting with the magnetization direction of the pinned magnetic layer. layers of antiferromagnetic and the first pinned magnetic layer in contact with the layer, the first pinned magnetic layer and the nonmagnetic intermediate layer through the second fixed magnetic layer to be overlaid 2
A first fixed magnetic layer and a second fixed magnetic layer.
The direction of the magnetic moment of the constant magnetic layer should be anti-parallel.
The magnetic moment of the first pinned magnetic layer (saturation magnetization Ms · thickness t) is, is different from the magnetic moment of the second pinned magnetic layer, the free magnetic layer, a nonmagnetic intermediate layer Is formed of two layers of a first free magnetic layer and a second free magnetic layer, and the absolute value of the combined magnetic moment of the magnetic moment of the first free magnetic layer and the magnetic moment of the second free magnetic layer is The absolute value of the combined magnetic moment of the magnetic moment of the first pinned magnetic layer and the magnetic moment of the second pinned magnetic layer is larger than the absolute value.

Further, according to the present invention, the nonmagnetic conductive layers stacked above and below the free magnetic layer, the upper fixed magnetic layer formed on one of the nonmagnetic conductive layers, and the other nonmagnetic conductive layer below. On the lower fixed magnetic layer and the upper fixed magnetic layer formed in
And a lower pinned magnetic layer and an antiferromagnetic layer formed below the pinned magnetic layer, wherein the upper and lower pinned magnetic layers and the free magnetic layer are magnetized in a direction intersecting each other. in the device, each of the fixed magnetic layer, a first pinned magnetic layer in contact with the antiferromagnetic layer, the first pinned magnetic layer and the nonmagnetic intermediate layer through the second fixed magnetic layer to be overlaid 2
A first fixed magnetic layer and a second fixed magnetic layer.
The direction of the magnetic moment of the constant magnetic layer should be anti-parallel.
The magnetic moment of the first pinned magnetic layer (saturation magnetization Ms · thickness t) is, is different from the magnetic moment of the second pinned magnetic layer, the free magnetic layer, a nonmagnetic intermediate layer Absolute value of a synthetic magnetic moment formed by adding the magnetic moment of the first free magnetic layer and the magnetic moment of the second free magnetic layer, which is formed by two layers of the first free magnetic layer and the second free magnetic layer. It is greater than the first absolute value of the magnetic moment and the synthesized magnetic moment obtained by adding the magnetic moment of the second pinned magnetic layer of the fixed magnetic layer in the upper fixed magnetic layer, and, first in the lower fixed magnetic layer 1 Is larger than the absolute value of the combined magnetic moment obtained by adding the magnetic moment of the pinned magnetic layer and the magnetic moment of the second pinned magnetic layer.

In the present invention, the above (magnetic thickness of first free magnetic layer / magnetic thickness of second free magnetic layer) is
It is preferably within the range of 0.56 to 0.83, or 1.25 to 5.

In the present invention, the above (magnetic thickness of the first free magnetic layer / magnetic thickness of the second free magnetic layer)
Is more preferably within the range of 0.61 to 0.83, or 1.25 to 2.1.

Further, in the present invention, the film thickness of the non-magnetic intermediate layer interposed between the first free magnetic layer and the second free magnetic layer is in the range of 5.5 to 10.0 angstroms. Is preferred.

In the present invention, the film thickness of the non-magnetic intermediate layer is more preferably in the range of 5.9 to 9.4 angstrom.

Further, the thin film magnetic head according to the present invention is
A shield layer is formed above and below the spin-valve type thin film element with a gap layer interposed therebetween.

In the present invention, the pinned magnetic layer constituting the spin-valve thin film element is divided into two layers, and the non-magnetic intermediate layer is formed between the two pinned magnetic layers.

The magnetizations of the two separated pinned magnetic layers are antiparallel to each other, and the magnitude of the magnetic moment (magnetic film thickness) of one pinned magnetic layer and the other pinned magnetic layer are the same. It is in a so-called ferri state in which the magnitude of the magnetic moment is different. The exchange coupling magnetic field (RKKY interaction) generated between the two fixed magnetic layers is 100
Since it is very large from 0 (Oe) to 5000 (Oe),
The two pinned magnetic layers are magnetized antiparallel in a very stable state.

By the way, the one pinned magnetic layer magnetized antiparallel (ferri state) is formed in contact with the antiferromagnetic layer, and the pinned magnetic layer on the side in contact with this antiferromagnetic layer (hereinafter,
The first pinned magnetic layer) is formed by an exchange coupling magnetic field (exchange anisotropic magnetic field) generated at the interface with the antiferromagnetic layer.
For example, the magnetization is fixed in the direction away from the surface facing the recording medium (height direction). As a result, the magnetization of the pinned magnetic layer (hereinafter, referred to as the second pinned magnetic layer) that faces the first pinned magnetic layer with the nonmagnetic intermediate layer interposed therebetween is opposite to the magnetization of the first pinned magnetic layer. It is fixed in a parallel state.

Conventionally, two layers, an antiferromagnetic layer and a pinned magnetic layer, are used.
In the present invention, the portion formed by the layer is divided into four layers of antiferromagnetic layer / first pinned magnetic layer / nonmagnetic intermediate layer / second pinned magnetic layer.
When the first pinned magnetic layer and the second pinned magnetic layer are formed of layers, the magnetization states of the first pinned magnetic layer and the second pinned magnetic layer can be kept very stable against an external magnetic field. In order to improve the magnetization stability of the second pinned magnetic layer, various conditions are required.

First, it is necessary to increase the exchange coupling magnetic field (exchange anisotropic magnetic field) generated at the interface between the antiferromagnetic layer and the first pinned magnetic layer. As described above, the magnetization of the first pinned magnetic layer is fixed in a certain direction by the exchange coupling magnetic field (exchange anisotropic magnetic field) generated at the interface with the antiferromagnetic layer, but this exchange coupling magnetic field is weak. Then, the pinned magnetization of the first pinned magnetic layer is not stable and is likely to change due to an external magnetic field or the like. Therefore, it is preferable that the exchange coupling magnetic field (exchange anisotropic magnetic field) generated at the interface with the antiferromagnetic layer is large, and in the present invention, a large exchange coupling magnetic field can be obtained at the interface with the first pinned magnetic layer. PtM as a possible antiferromagnetic layer
n alloys can be presented. Further, instead of the PtMn alloy, an X—Mn (X is Pd, Ir, Rh, Ru) alloy or Pt—Mn—X ′ (X ′ is Pd, Ir, Rh, Ru,
Au, Ag) alloys may be used.

These antiferromagnetic materials are NiO, FeMn alloys and Ni which have been conventionally used as antiferromagnetic materials.
It has excellent properties as an antiferromagnetic material, such as a large exchange coupling magnetic field, a high blocking temperature, and excellent corrosion resistance as compared with Mn alloys and the like.

FIG. 26 shows the present invention in which a PtMn alloy is used for the antiferromagnetic layer, and the pinned magnetic layer is divided into two layers, a first pinned magnetic layer and a second pinned magnetic layer via a non-magnetic intermediate layer. 3 is an RH curve of the spin-valve thin-film element in 1) and the conventional spin-valve thin-film element in which the fixed magnetic layer is formed of a single layer.

The film structure of the spin-valve type thin film element in the present invention is as follows from the bottom: Si substrate / alumina / Ta (30).
/ Antiferromagnetic layer; PtMn (200) / First pinned magnetic layer; Co (25) / Nonmagnetic intermediate layer; Ru (7) / Second pinned magnetic layer; Co (20) / Cu (20) / Co (1
0) / NiFe (40) / Ta (30), and the film structure of the conventional spin-valve type thin film element is S from the bottom.
i substrate / alumina / Ta (30) / antiferromagnetic layer; PtM
n (300) / fixed magnetic layer; Co (25) / Cu (2
0) / Co (10) / NiFe (40) / Ta (30)
Is. The numerical value in parentheses indicates the film thickness, and the unit is angstrom.

In both the present invention and the conventional spin-valve type thin film element, after film formation, heat treatment was performed at 260 ° C. for 4 hours while applying a magnetic field of 200 (Oe).

As shown in FIG. 26, the ΔMR (rate of change in resistance) of the spin-valve type thin film element in the present invention is between 7 and 8% at the maximum value, and by applying a negative external magnetic field, the aforementioned ΔMR is obtained. However, it can be seen that the decrease in ΔMR in the present invention is gentler than the decrease in ΔMR in the conventional spin-valve type thin film element.

In the present invention, the magnitude of the external magnetic field when the value of ΔMR is half the maximum value is defined as the exchange coupling magnetic field (Hex) generated by the spin valve thin film element.

As shown in FIG. 26, in the conventional spin valve thin film element, the maximum ΔMR is about 8%,
It can be seen that the external magnetic field (exchange coupling magnetic field (Hex)) when the ΔMR becomes half is about 900 (Oe) in absolute value.

On the other hand, in the spin-valve type thin film element according to the present invention, the maximum ΔMR is about 7.5%, which is slightly lower than the conventional value, but the external magnetic field (exchange) when the ΔMR becomes half is exchanged. It can be seen that the coupling magnetic field (Hex) is approximately 2800 (Oe) in absolute value, which is much larger than the conventional value.

As described above, in the spin valve thin film element of the present invention in which the pinned magnetic layer is divided into two layers, the spin valve thin film element in which the pinned magnetic layer is formed of one layer is replaced. It can be seen that the coupling magnetic field (Hex) can be dramatically increased and the magnetization stability of the pinned magnetic layer can be improved as compared with the conventional one. Further, it can be seen that the ΔMR does not decrease so much in the present invention as compared with the conventional one, and a high ΔMR can be maintained.

Next, FIG. 27 is a graph showing the relationship between the ambient temperature and the exchange coupling magnetic field using four types of spin valve thin film elements.

The first type of spin valve thin film element used is the spin valve thin film element of the present invention in which the PtMn alloy is used for the antiferromagnetic layer and the pinned magnetic layer is divided into two layers. , From the bottom, Si substrate / alumina / Ta (30) / antiferromagnetic layer; PtMn (200) /
First pinned magnetic layer; Co (25) / nonmagnetic intermediate layer; Ru
(7) / second pinned magnetic layer; Co (20) / Cu (2
0) / Co (10) / NiFe (70) / Ta (30)
Is.

The second type is a conventional example 1 in which a PtMn alloy is used for the antiferromagnetic layer and the pinned magnetic layer is formed as a single layer.
From the bottom, the film structure is Si substrate / alumina / Ta.
(30) / antiferromagnetic layer; PtMn (300) / fixed magnetic layer; Co (25) / Cu (25) / Co (10) / Ni
It is Fe (70) / Ta (30).

The third type is Conventional Example 2 in which NiO is used for the antiferromagnetic layer and the pinned magnetic layer is formed as a single layer. The film structure is as follows: Si substrate / alumina / antiferromagnetic layer. NiO (500) / fixed magnetic layer; Co (25) / C
u (25) / Co (10) / NiFe (70) / Ta
(30).

The fourth type is a conventional example 3 in which a fixed magnetic layer is formed of a single layer by using a FeMn alloy for the antiferromagnetic layer,
From the bottom, the film structure is Si substrate / alumina / Ta.
(30) / NiFe (70) / Co (10) / Cu (2
5) / fixed magnetic layer; Co (25) / antiferromagnetic layer; FeM
n (150) / Ta (30). In addition, 4 mentioned above
The numbers in parentheses for all types of film structure indicate the film thickness,
The unit is Angstrom.

In the present invention and the conventional example 1 in which PtMn is used for the antiferromagnetic layer, after film formation, heat treatment is performed at 260 ° C. for 4 hours while applying a magnetic field of 200 (Oe). Further, in Conventional Examples 2 and 3 in which NiO and FeMn are used for the antiferromagnetic layer, heat treatment is not performed after the film formation.

As shown in FIG. 27, in the spin valve thin film element of the present invention, the exchange coupling magnetic field (Hex) is about 2500 (Oe), which is very high when the ambient temperature is about 20 ° C.

On the other hand, Conventional Example 2 using NiO for the antiferromagnetic layer and Conventional Example 3 using FeMn for the antiferromagnetic layer.
Then, even if the ambient temperature is about 20 ° C, the exchange coupling magnetic field (Hex)
Is as low as about 500 (Oe) or less. Further, in Conventional Example 1 in which PtMn is used for the antiferromagnetic layer and the pinned magnetic layer is formed as a single layer, 1000 (O 2
It can be seen that an exchange coupling magnetic field of about e) is generated, and a larger exchange coupling magnetic field can be obtained than when NiO (conventional example 2) or FeMn (conventional example 3) is used for the antiferromagnetic layer.

In Japanese Unexamined Patent Publication No. 9-16920, an RH curve of a spin valve thin film element in which NiO is used for an antiferromagnetic layer and a pinned magnetic layer is formed of two layers with a non-magnetic intermediate layer interposed therebetween is shown in FIG. 8 is shown. According to FIG. 8 of the publication, 600
Although it is said that an exchange coupling magnetic field (Hex) of (Oe) can be obtained, this numerical value shows the exchange coupling magnetic field (about 10%) when PtMn is used for the antiferromagnetic layer and the pinned magnetic layer is formed as a single layer.
00 (Oe); lower than that of Conventional Example 1).

That is, when NiO is used for the antiferromagnetic layer, even if the pinned magnetic layer is divided into two layers and the magnetizations of the two pinned magnetic layers are made into a ferri state, the antiferromagnetic layer is formed. Since the exchange coupling magnetic field is lower than in the case where PtMn is used as the material and the pinned magnetic layer is formed as a single layer, the use of PtMn alloy in the antiferromagnetic layer provides a larger exchange coupling magnetic field. It can be seen that it is preferable in that it can be achieved.

As shown in FIG. 27, the antiferromagnetic layer has N
It can be seen that when the iO or FeMn alloy is used, the exchange coupling magnetic field becomes 0 (Oe) when the environmental temperature reaches about 200 ° C. This is the NiO and FeM
This is because the blocking temperature of n is as low as about 200 ° C.

On the other hand, in the conventional example 1 in which the PtMn alloy is used for the antiferromagnetic layer, the environmental temperature is about 400 ° C.,
The exchange coupling magnetic field is 0 (Oe), and the PtMn is
It is understood that the use of the alloy can keep the magnetization state of the pinned magnetic layer in a thermally very stable state.

Since the blocking temperature is governed by the material used for the antiferromagnetic layer, even in the spin valve thin film element according to the present invention shown in FIG. 27, the exchange coupling magnetic field is 0 (Oe) at about 400 ° C. However, when a PtMn alloy is used for the antiferromagnetic layer as in the present invention, it is possible to obtain a higher blocking temperature than NiO and the pinned magnetic layer is divided into two layers. If the magnetizations of the two pinned magnetic layers are changed to the ferri state, a very large exchange coupling magnetic field can be obtained before the blocking temperature is reached, and the magnetization state of the two pinned magnetic layers is thermally changed. It is possible to maintain a stable state.

In the present invention, the nonmagnetic intermediate layer formed between the first pinned magnetic layer and the second pinned magnetic layer is one of Ru, Rh, Ir, Cr, Re and Cu, or Using two or more types, the thickness of the non-magnetic intermediate layer is
By changing the case where the antiferromagnetic layer is formed below the free magnetic layer and the case where it is formed above the free magnetic layer, by forming the nonmagnetic intermediate layer with a film thickness within an appropriate range, The exchange coupling magnetic field (Hex) can be increased. The appropriate film thickness value of the non-magnetic intermediate layer will be described later in detail with reference to the graph.

Further, according to the present invention, if the pinned magnetic layer is divided into two layers, a large exchange coupling magnetic field (H) can be obtained even if the thickness of the antiferromagnetic layer formed of PtMn alloy or the like is reduced.
ex) can be obtained, and the antiferromagnetic layer, which had the thickest film thickness in the spin-valve type thin film element, can be thinned, so that the total film thickness of the spin-valve type thin film element as a whole can be reduced. Can be thin. Since the antiferromagnetic layer can be formed thin, even if the gap layers formed above and below the spin-valve thin-film element are thick enough to maintain sufficient insulation, the spin-valve thin-film element The distance from the gap layer formed on the lower side to the gap layer formed on the upper side of the spin-valve type thin film element, that is, the gap length can be shortened, and it is possible to cope with the narrowing of the gap.

By the way, as in the present invention, the pinned magnetic layer is
When the first pinned magnetic layer and the second pinned magnetic layer are divided into two layers via the non-magnetic intermediate layer, the film thicknesses of the first pinned magnetic layer and the second pinned magnetic layer are formed to have the same value. Then, it was found from an experiment that the exchange coupling magnetic field (Hex) and ΔMR (rate of change in resistance) are extremely lowered. When the first pinned magnetic layer and the second pinned magnetic layer are formed to have the same film thickness, the magnetization states of the first pinned magnetic layer and the second pinned magnetic layer are antiparallel (ferry state). It is presumed that this is because the magnetization states of the first pinned magnetic layer and the second pinned magnetic layer are not antiparallel to each other, so that the relative angle with the variable magnetization of the free magnetic layer is appropriately controlled. I can not do it.

Therefore, in the present invention, by forming the first pinned magnetic layer and the second pinned magnetic layer not to have the same film thickness but to have different film thicknesses, a large exchange coupling magnetic field can be obtained and at the same time. It is possible to make ΔMR as high as the conventional one. The film thickness ratio between the first pinned magnetic layer and the second pinned magnetic layer will be described later in detail with reference to the graph.

As described above, in the present invention, the pinned magnetic layer is divided into the two layers of the first pinned magnetic layer and the second pinned magnetic layer via the non-magnetic intermediate layer, and the PtMn alloy is further used as the antiferromagnetic layer. By using an antiferromagnetic material that exhibits a large exchange coupling magnetic field (exchange anisotropic magnetic field) at the interface with the first pinned magnetic layer, the exchange coupling magnetic field (Hex) of the entire spin-valve thin film element Can be increased, and the magnetizations of the first pinned magnetic layer and the second pinned magnetic layer can be maintained in a thermally stable antiparallel state (ferri state).

In the present invention, the film thickness ratio of the first pinned magnetic layer and the second pinned magnetic layer divided into two layers, the material of the non-magnetic intermediate layer, and the film thickness thereof, or the film of the antiferromagnetic layer. By optimizing the thickness and the like, the exchange coupling magnetic field of the entire spin-valve thin film element can be increased and a high ΔMR can be obtained.

The spin valve thin film element to which the present invention can be applied is a so-called single spin valve thin film element in which an antiferromagnetic layer, a fixed magnetic layer, a nonmagnetic conductive layer and a free magnetic layer are formed one by one. Alternatively, it may be a so-called dual spin valve thin film element in which a non-magnetic conductive layer, a pinned magnetic layer, and an antiferromagnetic layer are formed above and below the free magnetic layer as a center.

Further, in the present invention, the free magnetic layer may be divided into two layers with the nonmagnetic intermediate layer interposed therebetween, like the fixed magnetic layer. The magnetization of the first free magnetic layer and the second free magnetic layer formed via the non-magnetic intermediate layer is determined by the exchange coupling magnetic field (RKKY mutual) generated between the first free magnetic layer and the second free magnetic layer. Action)
The magnetizations are antiparallel and are aligned in a direction intersecting with the magnetizations of the pinned magnetic layers (first pinned magnetic layer and second pinned magnetic layer).

In the case of the pinned magnetic layers (first pinned magnetic layer and second pinned magnetic layer), the magnetization is pinned in a certain direction by the exchange coupling magnetic field (exchange anisotropic magnetic field) with the antiferromagnetic layer. However, the magnetization of the free magnetic layer is set to freely change by an external magnetic field, and the variation of the magnetization of the free magnetic layer depends on the relationship with the fixed magnetization direction of the fixed magnetic layer. The electric resistance changes, and the signal of the external magnetic field can be detected.

In the present invention, the ratio of the film thickness of the first free magnetic layer and the film thickness of the second free magnetic layer divided by the nonmagnetic intermediate layer and the film thickness of the nonmagnetic intermediate layer are By optimizing, the anti-parallel state (ferri state) between the first pinned magnetic layer and the second pinned magnetic layer can be maintained in a thermally stable state, and a high ΔMR comparable to the conventional one can be obtained. I have to. Regarding the film thickness ratio of the first free magnetic layer and the second free magnetic layer and the film thickness value of the non-magnetic intermediate layer,
The details will be described later with reference to the graph.

[0057]

1 is a cross-sectional view schematically showing a spin valve thin film element according to a first embodiment of the present invention, and FIG. 2 shows the spin valve thin film element of FIG. 1 as a recording medium. 3 is a cross-sectional view seen from the facing surface side of FIG.

Above and below this spin valve thin film element,
A shield layer is formed via a gap layer, and the spin valve thin film element, the gap layer, and the shield layer constitute a thin film magnetic head (MR head) for reproduction. A recording inductive head may be laminated on the reproducing thin film magnetic head.

The thin-film magnetic head is provided at the trailing side end of the floating slider provided in the hard disk device and detects the recording magnetic field of the hard disk. The moving direction of the magnetic recording medium such as a hard disk is the Z direction in the figure, and the direction of the leakage magnetic field from the magnetic recording medium is the Y direction.

The spin valve thin film element shown in FIGS. 1 and 2 is a so-called single spin valve thin film element in which an antiferromagnetic layer, a pinned magnetic layer, a non-magnetic conductive layer and a free magnetic layer are formed one by one. , The bottom layer is
The underlayer 10 is made of a nonmagnetic material such as Ta.
In FIGS. 1 and 2, an antiferromagnetic layer 11 is formed on the underlayer 10, and a first pinned magnetic layer 12 is formed on the antiferromagnetic layer 11. As shown in FIG. 1, a nonmagnetic intermediate layer 13 is formed on the first pinned magnetic layer 12, and a second pinned magnetic layer 14 is further formed on the nonmagnetic intermediate layer 13. .

The first pinned magnetic layer 12 and the second pinned magnetic layer 14 are, for example, Co film, NiFe alloy, CoNi.
It is formed of an Fe alloy, a CoFe alloy, or the like.

In the present invention, the antiferromagnetic layer 11 is
It is preferably formed of a PtMn alloy. PtM
The n alloy is an N alloy that has been conventionally used as an antiferromagnetic layer.
Excellent corrosion resistance compared to iMn alloy and FeMn alloy,
Moreover, the blocking temperature is high and the exchange coupling magnetic field (exchange anisotropic magnetic field) is large. In the present invention, instead of the PtMn alloy, X-Mn (where X is Pd, Ir, R
h or Ru, which is one or more elements)
Alloy or Pt-Mn-X '(where X'is P
d, Ir, Rh, Ru, Au, Ag, which is one kind or two or more kinds of elements).

By the way, the first pinned magnetic layer 12 shown in FIG.
Arrows shown on the second pinned magnetic layer 14 and the second pinned magnetic layer 14 indicate the magnitudes and directions of the respective magnetic moments, and the magnitudes of the magnetic moments are the saturation magnetization (Ms).
And the film thickness (t).

The first pinned magnetic layer 12 and the second pinned magnetic layer 12 shown in FIG.
It is formed of the same material as the pinned magnetic layer 14, for example, a Co film.
In addition, the film thickness t of the second pinned magnetic layer 14_P2But the first
The thickness t of the pinned magnetic layer 12_P1Is formed larger than
For this reason, the second pinned magnetic layer 14 is better than the first pinned magnetic layer.
The magnetic moment is larger than that of No. 12. In addition,
In the present invention, the first pinned magnetic layer 12 and the second pinned magnetic layer 12
Requires that the layers 14 have different magnetic moments
Therefore, the film thickness t of the first pinned magnetic layer 12 is therefore _P1Is the first
The thickness t of the pinned magnetic layer 14 of No. 2_P2Formed thicker
Good.

As shown in FIG. 1, the first pinned magnetic layer 12 is magnetized in the Y direction shown in the drawing, that is, in the direction away from the recording medium (height direction), and is opposed to the second magnetic layer 13 with the nonmagnetic intermediate layer 13 interposed therebetween. The magnetization of the pinned magnetic layer 14 is magnetized antiparallel to the magnetization direction of the first pinned magnetic layer 12.

The first pinned magnetic layer 12 is the antiferromagnetic layer 11
The first pinned magnetic layer 12 and the antiferromagnetic layer 11 by being annealed (heat treatment) in a magnetic field.
An exchange coupling magnetic field (exchange anisotropic magnetic field) is generated at the interface between the first pinned magnetic layer 1 and the first pinned magnetic layer 1 as shown in FIG.
The magnetization of 2 is fixed in the Y direction shown. When the magnetization of the first pinned magnetic layer 12 is pinned in the Y direction in the drawing, the magnetization of the second pinned magnetic layer 14 that faces the non-magnetic intermediate layer 12 is the same as that of the first pinned magnetic layer 12. It is fixed in a state antiparallel to the magnetization.

In the present invention, the film thickness ratio t _{P1 of} the first pinned magnetic layer 12 and the film thickness ratio t _P2 of the second pinned magnetic layer 14 are optimized so that (the film thickness of the first pinned magnetic layer). Thickness t _P1 ) / (Second
The thickness t _P2 of the pinned magnetic layer is preferably 0.33 to 0.95, or 1.05 to 4. The exchange coupling magnetic field can be increased within this range, but even within the above range, the exchange coupling magnetic field tends to decrease as the film thickness of the first pinned magnetic layer 12 and the second pinned magnetic layer 14 itself increases. Therefore, in the present invention, the film thicknesses of the first pinned magnetic layer 12 and the second pinned magnetic layer 14 are optimized.

[0068] In the present invention, the thickness t _P2 of the first thickness of the pinned magnetic layer 12 t _P1 and the second fixed magnetic layer 14 is 10 to 70
Within the range of angstrom, and the first pinned magnetic layer 1
The absolute value obtained by subtracting the film thickness t _P2 of the second pinned magnetic layer 14 from the film thickness t _P1 of 2 is preferably 2 angstroms or more.

By properly adjusting the film thickness ratio and film thickness within the above range, it is possible to obtain an exchange coupling magnetic field (Hex) of at least 500 (Oe) or more. Here, the exchange coupling magnetic field is the magnitude of the external magnetic field when the maximum ΔMR (resistance change rate) is ΔMR, and the exchange coupling magnetic field (Hex) is the same as that of the antiferromagnetic layer 11 and the first magnetic field. Exchange magnetic field (exchange anisotropic magnetic field) generated at the interface with the pinned magnetic layer 12 and the exchange coupling magnetic field (RKKY interaction) generated between the first pinned magnetic layer 12 and the second pinned magnetic layer 14. ) Is a comprehensive one including all magnetic fields.

Further, in the present invention, the above (film thickness t _{P1 of} the first pinned magnetic layer) / (film thickness t _{P2 of} the second pinned magnetic layer) is
More preferably, it is within the range of 0.53 to 0.95, or 1.05 to 1.8. The A in the above range, the film thickness t _P1 of the first pinned magnetic layer 12 has a thickness t _P2 of the second pinned magnetic layer 14 are both within the range of 10 to 50 angstroms, yet the first fixed Thickness of magnetic layer 12 t _P1
The absolute value obtained by subtracting the film thickness t _P2 of the second pinned magnetic layer 14 from is preferably 2 angstroms or more. Within the above range, the first pinned magnetic layer 12 and the second pinned magnetic layer 14
Of the first pinned magnetic layer 12 and the film thickness ratio t _{P1 of} the first pinned magnetic layer 12
By properly adjusting the film thickness t _P2 of the pinned magnetic layer 14, it is possible to obtain an exchange coupling magnetic field of at least 1000 (Oe) or more.

If the film thickness ratio and film thickness are within the above range, the exchange coupling magnetic field (Hex) can be increased, and at the same time, Δ
The MR (rate of change in resistance) can be increased to the same level as the conventional one.

The larger the exchange coupling magnetic field, the more stable the magnetization of the first pinned magnetic layer 12 and the magnetization of the second pinned magnetic layer 14 can be kept in antiparallel state. By using a PtMn alloy that has a high blocking temperature and generates a large exchange coupling magnetic field (exchange anisotropic magnetic field) at the interface with the first pinned magnetic layer 12 as the magnetic layer 11, the first pinned magnetic layer is formed. The magnetization states of 12 and the second pinned magnetic layer 14 can be maintained thermally stable.

By the way, the first pinned magnetic layer 12 and the second pinned magnetic layer 14 are formed of the same material, and the film thickness of the first pinned magnetic layer 12 and the second pinned magnetic layer 14 is different. It has been confirmed by experiments that the exchange coupling magnetic field (Hex) and ΔMR are extremely lowered when the values are the same.

This is Ms · t of the first pinned magnetic layer 12.
_P1 (magnetic moment) and Ms of the second pinned magnetic layer 14
When t _P2 (magnetic moment) has the same value, the magnetization of the first pinned magnetic layer 12 and the magnetization of the second pinned magnetic layer 14 do not become antiparallel, and the direction dispersion amount of the magnetization is This is because the relative angle with respect to the magnetization of the free magnetic layer 16, which will be described later, cannot be properly controlled due to the increase in (the amount of magnetic moments oriented in various directions).

In order to solve such a problem, first, Ms of the first pinned magnetic layer 12 and the second pinned magnetic layer 14 is set.
When the values of t are different, that is, when the first pinned magnetic layer 12 and the second pinned magnetic layer 14 are formed of the same material, the first pinned magnetic layer 12 and the second pinned magnetic layer It is necessary to form the magnetic layers 14 with different film thicknesses.

In the present invention, as described above, the film thickness ratio of the first pinned magnetic layer 12 and the second pinned magnetic layer 14 is optimized. If the film thickness t _P1 of the fixed magnetic layer 12 and the thickness t _P2 of the second pinned magnetic layer 14 is approximately the same value, specifically, 0.95 to 1.0
The film thickness ratio within the range of 5 is excluded from the proper range.

Then, as in the present invention, after the PtMn alloy or the like is formed on the antiferromagnetic layer 11, it is annealed (heat treatment) in a magnetic field.
When an antiferromagnetic material that generates an exchange coupling magnetic field (exchange anisotropic magnetic field) at the interface with the first pinned magnetic layer 12 by applying Even if Ms · t of the pinned magnetic layer 14 is set to a different value, the magnetization of the first pinned magnetic layer 12 and the second pinned magnetic layer 12 are not controlled unless the direction and the magnitude of the applied magnetic field during the heat treatment are properly controlled. The amount of directional dispersion increases in the magnetization of the pinned magnetic layer 14, or the magnetization cannot be properly controlled in the desired direction.

[0078]

[Table 1]

In Table 1, Ms · of the first pinned magnetic layer 12 is
When t _P1 is larger than Ms · t _{P2 of} the second pinned magnetic layer, the first pinned magnetic layer 12 and the second pinned magnetic layer 12 are changed by changing the magnitude and direction of the magnetic field during the heat treatment. It indicates in which direction the magnetization of 14 is oriented.

In (1) of Table 1, the direction of the magnetic field during the heat treatment is given to the left side in the figure of 100 to 1 k (Oe). In this case, the Ms · t _P1 of the first pinned magnetic layer 12 is the second
Is larger than Ms · t _P2 of the pinned magnetic layer 14, the magnetization of the dominant first pinned magnetic layer 12 is directed to the left in the figure following the applied magnetic field direction, and the magnetization of the second pinned magnetic layer 14 is The magnetization is an exchange coupling magnetic field (RKK) with the first pinned magnetic layer 12.
Y-interaction) and the anti-parallel state is attempted.

In (2) of Table 1, 100 to 1 k to the right.
When a magnetic field of (Oe) is applied, the dominant magnetization of the first pinned magnetic layer 12 is directed to the right following the applied magnetic field direction, and the magnetization of the second pinned magnetic layer 14 is changed to the first pinned magnetic layer. It is antiparallel to the magnetization of layer 12.

In (3) of Table 1, 5k (Oe) to the right.
When the above magnetic field is applied, the dominant magnetization of the first pinned magnetic layer 12 is directed rightward following the applied magnetic field direction.
By the way, the first pinned magnetic layer 12 and the second pinned magnetic layer 1
Exchange coupling magnetic field (RKKY interaction) generated between 4 and
Is about 1 k (Oe) to 5 k (Oe), so 5 k
When a magnetic field of (Oe) or more is applied, the second pinned magnetic layer 14 also faces the applied magnetic field direction, that is, the right direction in the drawing.
Similarly, in (4) of Table 1, when a magnetic field of 5 k (Oe) or more is applied to the left, both the magnetizations of the first pinned magnetic layer 12 and the second pinned magnetic layer 14 are directed to the left in the drawing.

[0083]

[Table 2]

In Table 2, Ms of the first pinned magnetic layer 12
When t _P1 is smaller than Ms · t _{P2 of} the second pinned magnetic layer, the magnitude and direction of the applied magnetic field during the heat treatment are changed to change the first pinned magnetic layer 12 and the second pinned magnetic layer. It indicates in which direction the magnetization of 14 is oriented.

In (1) of Table 2, 100 to 100 in the leftward direction in the figure.
When a magnetic field of 1 k (Oe) is applied, the magnetization of the second pinned magnetic layer 14 having a large Ms · t _P2 becomes dominant, and the magnetization of the second pinned magnetic layer 14 follows the applied magnetic field direction, Turn to the left in the figure. Due to exchange coupling (RKKY interaction) between the first pinned magnetic layer 12 and the second pinned magnetic layer 14, the magnetization of the first pinned magnetic layer 12 becomes the magnetization of the second pinned magnetic layer 14. It becomes anti-parallel. Similarly, in (2) of Table 2, when a magnetic field of 100 to 1 k (Oe) is applied to the right in the drawing, the dominant magnetization of the second pinned magnetic layer 14 is directed to the right in the drawing, and the first pinned The magnetization of the magnetic layer 12 is directed to the left in the drawing.

In (3) of Table 2, 5k (O
When a magnetic field of e) or more is applied, a magnetic field of exchange coupling (RKKY interaction) or more between the first pinned magnetic layer 12 and the second pinned magnetic layer 14 is applied, whereby the first pinned magnetic layer The magnetizations of the layer 12 and the second pinned magnetic layer 14 are both
Turn to the right in the figure. In (4) of Table 2, 5 to the left in the figure.
When a magnetic field of k (Oe) or more is applied, the magnetizations of the first pinned magnetic layer 12 and the second pinned magnetic layer 14 are both directed to the left in the drawing.

Here, for example, when the magnetization of the first pinned magnetic layer 12 is to be directed to the right in the drawing, the magnetic field direction and its magnitude during the appropriate heat treatment are (2) in Table 1.
(3) and (1) and (3) in Table 2.

In both Tables 1 (2) and (3), the magnetization of the first pinned magnetic layer 12 having a large Ms · t _P1 is influenced by the applied magnetic field in the right direction during the heat treatment, and is oriented in the right direction. At this time, the magnetization of the first pinned magnetic layer 12 is pinned to the right by the exchange coupling magnetic field (exchange anisotropy field) at the interface with the antiferromagnetic layer 11 generated by the heat treatment. In Table 1 (3), if a magnetic field of 5 k (Oe) or more is removed,
The second pinned magnetic layer 14 reverses the magnetization of the second pinned magnetic layer 14 by the exchange coupling magnetic field (RKKY interaction) generated between the second pinned magnetic layer 14 and the first pinned magnetic layer 12, and faces the left direction. .

Similarly, in Tables 2 (1) and (3), the magnetization of the first pinned magnetic layer 12 oriented to the right is the antiferromagnetic layer 1
It is fixed to the right by the exchange coupling magnetic field (exchange anisotropic magnetic field) at the interface with 1. In Table 2 (3), 5k (O
e) When the above magnetic field is removed, the second pinned magnetic layer 14 is removed.
The magnetization of the second pinned magnetic layer 14 is inverted by the exchange coupling magnetic field (RKKY interaction) generated between the second pinned magnetic layer 12 and the first pinned magnetic layer 12, and pinned to the left.

By the way, as shown in Tables 1 and 2, the magnitude of the magnetic field applied during the heat treatment is 100 to 1 k (O
e), or 5k (Oe) or more and 1k (Oe)
The magnitude of the magnetic field in the range of up to 5 k (Oe) is out of the proper range. This is for the following reasons.

By applying a magnetic field, the magnetization of the pinned magnetic layer having a large Ms · t tends to move in the direction of the magnetic field. However, the magnitude of the magnetic field during the heat treatment is 1 k (Oe)
If it is between ˜5 k (Oe), the magnetization of the pinned magnetic layer with a small Ms · t is strongly influenced by the magnetic field and tends to move in the magnetic field direction. For this reason, the magnetizations of the two fixed magnetic layers, which tend to become antiparallel due to the exchange coupling magnetic field (RKKY interaction) generated between the fixed magnetic layers, are not antiparallel due to the influence of the strong magnetic field, and the fixed The magnetization of the magnetic layer tends to move in various directions, that is, the so-called magnetization dispersion amount increases, and the magnetizations of the two fixed magnetic layers cannot be properly magnetized in the antiparallel state. Therefore, in the present invention, 1
The magnitude of the magnetic field of k (Oe) to 5k (Oe) is out of the proper range. The magnitude of the magnetic field during the heat treatment is 10
The reason why it is set to 0 (Oe) or more is that the magnetization of the pinned magnetic layer having a large Ms · t cannot be oriented in the applied magnetic field direction unless a magnetic field of this degree is applied.

The method of controlling the magnitude and direction of the magnetic field during the heat treatment described above is not limited to the case where the antiferromagnetic layer 11 requiring the heat treatment is used and which antiferromagnetic material is used. Can also be applied, for example, when a NiMn alloy conventionally used as the antiferromagnetic layer 11 is used.

As described above, in the present invention, the exchange coupling magnetic field (Hex) can be increased by keeping the film thickness ratio between the first pinned magnetic layer 12 and the second pinned magnetic layer 14 within an appropriate range. , The first pinned magnetic layer 12 and the second pinned magnetic layer 1
It is possible to maintain the magnetization of No. 4 in an antiparallel state (ferri state) that is also thermally stable and to secure ΔMR (resistance change rate) to the same level as in the conventional case.

Further, by appropriately controlling the magnitude and direction of the magnetic field during the heat treatment, the first pinned magnetic layer 1
It is possible to control the magnetization directions of the second and second pinned magnetic layers 14 to desired directions.

As described above, the magnetic moment (magnetic film thickness) can be obtained by the product of the saturation magnetization Ms and the film thickness t. For example, in the case of bulk solid NiFe, the saturation magnetization Ms is about When it is 1.0 T (tesla) and Co is a bulk solid, the saturation magnetization Ms is about 1.
It is known to be 7T. Therefore, the NiFe
If the film thickness is 30 Å, the Ni
The magnetic film thickness of the Fe film is 30 angstrom tesla. Since the magnetostatic energy of a ferromagnetic film when a magnetic field is applied from the outside is proportional to the multiplication of the magnetic film thickness and the external magnetic field, the ferromagnetic film having a large magnetic film thickness and the strong magnetic film having a small magnetic film thickness. When the magnetic film is in the ferri state due to the RKKY interaction through the non-magnetic intermediate layer, the ferromagnetic film having the larger magnetic film thickness tends to direct the direction of the external magnetic field.

However, in the case of a ferromagnetic film laminated contact with a non-magnetic film such as tantalum (Ta), ruthenium (Ru) or copper (Cu), or a ferromagnetic film laminated contact with an antiferromagnetic layer such as a PtMn film. In the case of, the non-magnetic film atom or the anti-ferromagnetic film atom and the ferromagnetic film atom (Ni, Fe, Co) directly contact each other, so that the saturation magnetization Ms of the ferromagnetic film near the interface between the non-magnetic film and the anti-ferromagnetic film is Ms. Is smaller than the saturation magnetization Ms of the bulk solid. Further, when heat treatment is applied to the laminated multilayer film of the ferromagnetic film, the non-magnetic film, and the antiferromagnetic layer, interface diffusion progresses due to the heat treatment, and the saturation magnetization Ms of the ferromagnetic film has a distribution in the film thickness direction. It is known.
That is, it is a phenomenon that the saturation magnetization Ms is small near the nonmagnetic film or the antiferromagnetic layer, and the saturation magnetization Ms approaches the saturation magnetization Ms of the bulk solid as the distance from the interface with the nonmagnetic film or the antiferromagnetic film increases. .

The decrease in the saturation magnetization Ms of the ferromagnetic film near the nonmagnetic film or the antiferromagnetic layer is caused by the material of the nonmagnetic film, the material of the antiferromagnetic layer, the material of the ferromagnetic film, the stacking order, the heat treatment temperature. To be precise, it must be obtained in each specified condition. The magnetic film thickness in the present invention is a value calculated in consideration of the decrease amount of the saturation magnetization Ms caused by thermal diffusion with the non-magnetic film or the antiferromagnetic layer.

In order to obtain an exchange coupling magnetic field at the interface between the PtMn film and the ferromagnetic film, it is necessary to form a diffusion layer at the interface between the PtMn film and the ferromagnetic film by heat treatment. The decrease in the saturation magnetization Ms of the ferromagnetic film due to
It depends on the stacking order of the tMn film and the ferromagnetic film.

In particular, as shown in FIG. 1, when the antiferromagnetic layer 11 is formed below the free magnetic layer 16, the antiferromagnetic layer 11 and the first pinned magnetic layer 12 are formed. A thermal diffusion layer is likely to be generated at the interface between the first pinned magnetic layer 12 and the first pinned magnetic layer 12, and the magnetic film thickness of the first pinned magnetic layer 12 is smaller than the actual film thickness t _P1 . However, the first pinned magnetic layer 1
If the magnetic film thickness of 2 is too small, the magnetic film thickness (magnetic moment) difference from the second pinned magnetic layer 14 becomes too large, and the thermal diffusion layer occupying the first pinned magnetic layer 12 becomes too large. There is a problem that the increase in the ratio leads to a decrease in the exchange coupling magnetic field.

That is, as in the present invention, the antiferromagnetic layer 11 that requires heat treatment to generate an exchange coupling magnetic field at the interface with the first pinned magnetic layer 12 is used, and the first pinned magnetic layer is used. 12 and the second pinned magnetic layer 14 are brought into a ferrimagnetic state, the first pinned magnetic layer 12 and the second pinned magnetic layer
In addition to optimizing the film thickness of the pinned magnetic layer 14,
Unless the magnetic film thicknesses of the pinned magnetic layer 12 and the second pinned magnetic layer 14 are optimized, a stable magnetization state cannot be maintained.

As described above, if there is no difference in the magnetic film thickness between the first pinned magnetic layer 12 and the second pinned magnetic layer 14 to some extent, the magnetization state is unlikely to become the ferri state, and the first pinned magnetic layer is fixed. Even if the difference in magnetic film thickness between the magnetic layer 12 and the second pinned magnetic layer 14 becomes too large, the exchange coupling magnetic field is lowered, which is not preferable. Therefore, in the present invention, as in the film thickness ratio of the first pinned magnetic layer 12 and the second pinned magnetic layer 14,
(Magnetic film thickness of first pinned magnetic layer 12) / (Magnetic film thickness of second pinned magnetic layer 14) is in the range of 0.33 to 0.95, or 1.05 to 4. Preferably there is.
Further, in the present invention, the magnetic thickness of the first pinned magnetic layer 12 and the magnetic thickness of the second pinned magnetic layer 14 are within the range of 10 to 70 (angstrom tesla), and the first pinned magnetic layer is formed. The absolute value obtained by subtracting the magnetic film thickness of the second pinned magnetic layer 14 from the magnetic film thickness of the layer 12 is preferably 2 (angstrom tesla) or more.

Further, (magnetic film thickness of first pinned magnetic layer 12) / (magnetic film thickness of second pinned magnetic layer 14) is 0.
It is more preferably within the range of 53 to 0.95, or 1.05 to 1.8. Within the above range, the magnetic thickness of the first pinned magnetic layer 12 and the second pinned magnetic layer 1
4 has a magnetic film thickness of 10 to 50 (angstrom
Tesla) and the first pinned magnetic layer 12
The absolute value obtained by subtracting the magnetic film thickness of the second pinned magnetic layer 14 from the magnetic film thickness of is preferably 2 (angstrom tesla) or more.

Next, the non-magnetic intermediate layer 1 interposed between the first pinned magnetic layer 12 and the second pinned magnetic layer 14 shown in FIG.
3 will be described.

In the present invention, the first pinned magnetic layer 12 and the second pinned magnetic layer 12
Non-magnetic intermediate layer 13 interposed between the fixed magnetic layer 14 and
Is preferably formed of an alloy of one or more of Ru, Rh, Ir, Cr, Re and Cu.

In the present invention, depending on whether the antiferromagnetic layer 11 is formed below or above the free magnetic layer 16 which will be described later, an appropriate film thickness value of the nonmagnetic intermediate layer 13 is obtained. Is changing.

As shown in FIG. 1, when the antiferromagnetic layer 11 is formed below the free magnetic layer 16, the thickness of the nonmagnetic intermediate layer 13 is 3.6 to 9.6 angstroms. It is preferably formed within the range. Within this range, exchange coupling magnetic field (Hex) of 500 (Oe) or more
It is possible to obtain

The thickness of the non-magnetic intermediate layer 13 is 4 to 4.
Formed within the range of 9.4 angstroms, 10
It is more preferable because an exchange coupling magnetic field of 00 (Oe) or more can be obtained.

It has been confirmed by experiments that the exchange coupling magnetic field is extremely lowered when the thickness of the non-magnetic intermediate layer 13 is formed to a dimension other than the above-mentioned dimension. That is, when the non-magnetic intermediate layer 13 is formed with dimensions other than the above dimensions, the first pinned magnetic layer 12 and the second pinned magnetic layer 14 are formed.
There is a problem that the magnetizations of and become less likely to be in an antiparallel state (ferri state), and the magnetization state becomes unstable.

As shown in FIG. 1, the second pinned magnetic layer 14
A nonmagnetic conductive layer 15 made of Cu or the like is formed on the above, and a free magnetic layer 16 is further formed on the nonmagnetic conductive layer 15. As shown in FIG. 1, the free magnetic layer 16 is formed of two layers, and the nonmagnetic conductive layer 1 is
The layer of reference numeral 17 formed on the side in contact with 5 is formed of a Co film. The other layer 18 is made of a NiFe alloy, a CoFe alloy, a CoNiFe alloy, or the like. In addition, Co on the side in contact with the non-magnetic conductive layer 15
The reason for forming the film layer 17 is that diffusion of a metal element or the like at the interface with the non-magnetic conductive layer 15 formed of Cu can be prevented, and ΔMR (resistance change rate) can be increased. Reference numeral 19 is a protective layer formed of Ta or the like.

As shown in FIG. 2, the hard bias layer 130 and Cu formed of, for example, a Co—Pt alloy or a Co—Cr—Pt alloy are provided on both sides of the laminated body from the underlayer 10 to the protective layer 19. Conductive layer 131 made of Cr or Cr
Are formed, and the magnetization of the free magnetic layer 16 is magnetized in the X direction in the figure under the influence of the bias magnetic field of the hard bias layer.

In the spin-valve type thin film element shown in FIG. 1, the free magnetic layer 16 and the non-magnetic conductive layer 1 are formed from the conductive layer.
5, and a sense current is applied to the second pinned magnetic layer 14. When a magnetic field is applied from the recording medium to the Y direction shown in FIG. 1, the magnetization of the free magnetic layer 16 changes from the X direction to the Y direction, and the interface between the nonmagnetic conductive layer 15 and the free magnetic layer 16 at this time. , And spin-dependent scattering of conduction electrons occurs at the interface between the non-magnetic conductive layer 15 and the second pinned magnetic layer 14, the electric resistance changes, and a leakage magnetic field from the recording medium is detected.

By the way, the sense current actually flows in the interface between the first pinned magnetic layer 12 and the non-magnetic intermediate layer 13 and the like. The first pinned magnetic layer 12 does not directly participate in ΔMR, and the first pinned magnetic layer 12 fixes the second pinned magnetic layer 14 involved in ΔMR in an appropriate direction.
It is, so to speak, a layer that played an auxiliary role. Therefore, the sense current flowing to the first pinned magnetic layer 12 and the non-magnetic intermediate layer 13 causes a shunt loss (current loss), but the amount of this shunt loss is very small. It is possible to obtain ΔMR that is almost the same as

By the way, in the present invention, the pinned magnetic layer is divided into the first pinned magnetic layer 12 and the second pinned magnetic layer 14 via the non-magnetic intermediate layer 13, whereby the antiferromagnetic layer 1 is formed.
Even if the film thickness of 1 is reduced, a large exchange coupling magnetic field (He
It has been experimentally found that x), specifically, an exchange coupling magnetic field of 500 (Oe) or more can be obtained.

Conventionally, when a PtMn alloy is used as the antiferromagnetic layer 11 of a single spin valve type thin film element,
An exchange coupling magnetic field of 500 (Oe) or more could not be obtained unless a film thickness of at least 200 angstroms was secured, but in the present invention, the antiferromagnetic layer 11 is used.
Is formed at least 90 angstroms or more,
It is possible to obtain an exchange coupling magnetic field of 500 (Oe) or more. If the film thickness is 100 angstroms or more, it is possible to obtain an exchange coupling magnetic field of 1000 (Oe) or more. The numerical range of the film thickness of the antiferromagnetic layer 11 is for a single spin valve thin film element,
In the case of a so-called dual spin-valve type thin film element in which the antiferromagnetic layer is formed above and below the free magnetic layer, the appropriate film thickness range is slightly different. The case of the dual spin valve thin film element will be described later.

As described above, according to the present invention, the antiferromagnetic layer 11 having the largest film thickness in the spin-valve type thin film element can be formed to have a film thickness of half or less as compared with the conventional one. It is possible to reduce the film thickness of the entire valve type thin film element.

FIG. 13 is a cross-sectional view of the structure of a read head having a spin valve thin film element formed, as viewed from the side facing the recording medium.

Reference numeral 120 is a lower shield layer made of, for example, a NiFe alloy, and a lower gap layer 121 is formed on the lower shield layer 120.
A spin valve thin film element 122 of the present invention is formed on the lower gap layer 121, and a hard bias layer 123 and a conductive layer 124 are formed on both sides of the spin valve thin film element 122. Further, an upper gap layer 125 is formed on the conductive layer 124, and NiFe is formed on the upper gap layer 125.
An upper shield layer 126 made of an alloy or the like is formed.

The lower gap layer 123 and the upper gap layer 125 are made of, for example, SiO ₂ or Al ₂ O ₃ (alumina).
It is formed of an insulating material such as. As shown in FIG. 13, from the lower gap layer 121 to the upper gap layer 12
The length up to 5 is the gap length Gl, and the smaller the gap length Gl, the higher the recording density can be supported.

In the present invention, as described above, the antiferromagnetic layer 1
Since the thickness of the spin valve thin film element 122 as a whole can be made thinner by making the film thickness of 1 smaller, the gap length G
It is possible to shorten l. Also, the lower gap layer 1
21 and the upper gap layer 125 can be made relatively thick, the gap length Gl can be made smaller than in the conventional case, and the lower gap layer 121 and the upper gap layer 12 can be formed.
By forming 5 thick, it is possible to ensure sufficient insulation.

In the spin-valve thin film element shown in FIG. 1, first, from the bottom, an underlayer 10, an antiferromagnetic layer 11, a first pinned magnetic layer 12, a nonmagnetic intermediate layer 13, a second pinned magnetic layer 14, and a non-magnetic layer. The magnetic conductive layer 15, the free magnetic layer 16, and the protective layer 19 are formed, and annealing (heat treatment) in a magnetic field is performed in the step after the film formation.

In the spin valve thin film element shown in FIG.
The film thickness t _{P1 of} the first pinned magnetic layer 12 is smaller than the film thickness t _P2 of the second pinned magnetic layer 14, and the magnetic moment (Ms · t _P1 ) of the first pinned magnetic layer 12 is set. Is smaller than the magnetic moment (Ms · t _P2 ) of the second pinned magnetic layer 14.

In this case, in the direction opposite to the direction in which the magnetization of the first pinned magnetic layer 14 is desired, 100 to 1000 (O
The magnetic field of e) is applied, or a magnetic field of 5 k (Oe) or more is applied in the direction in which the magnetization is desired to be directed.

As shown in FIG. 1, the first pinned magnetic layer 12 is formed.
When it is desired to fix the magnetization of Y in the Y direction shown in the drawing, by referring to the above-mentioned Table 2, it is possible to set 10
Apply a magnetic field of 0 to 1k (Oe) (see Table 2 (1)) or 5k (Oe) in the Y direction (see Table 2 (3))
It can be seen that the above magnetic field may be applied.

100 to 1 k (Oe) in the direction opposite to the Y direction
The magnetic moment (Ms · t _P2 )
The magnetization of the second pinned magnetic layer 14 having a large magnetic field is magnetized in the direction opposite to the Y direction, and is magnetized antiparallel by the exchange coupling magnetic field (RKKY interaction) with the second pinned magnetic layer. The magnetization of the pinned magnetic layer 12 of FIG.
Due to the exchange coupling magnetic field (exchange anisotropic magnetic field) generated at the interface with the antiferromagnetic layer 11, the first pinned magnetic layer 1 is formed.
The magnetization of 2 is fixed in the Y direction shown. Since the magnetization of the first pinned magnetic layer 12 is pinned in the Y direction in the drawing,
The magnetization of the pinned magnetic layer 14 is pinned antiparallel to the magnetization of the first pinned magnetic layer 12.

Alternatively, when a magnetic field of 5 k (Oe) or more is applied in the Y direction shown in the figure, the magnetizations of the first pinned magnetic layer 12 and the second pinned magnetic layer 14 are both magnetized in the Y direction shown in the figure, and the first pinned magnetic layer is magnetized. The magnetization of the layer 12 is indicated by Y in the figure due to the exchange coupling magnetic field (exchange anisotropic magnetic field) generated at the interface with the antiferromagnetic layer 11.
Fixed in the direction. When the applied magnetic field of 5 k (Oe) or more is removed, the magnetization of the second pinned magnetic layer 14 is reversed by the exchange coupling magnetic field (RKKY interaction) with the first pinned magnetic layer 12, and the direction opposite to the Y direction in the drawing is shown. Fixed to.

Alternatively, when the magnetic moment of the first pinned magnetic layer 12 is larger than that of the second pinned magnetic layer 14, the magnetization of the first pinned magnetic layer 12 is directed in the desired direction. 100-1000 (Oe) or 5
A magnetic field of k (Oe) or more is applied.

The spin-valve type thin film element shown in FIG. 1 is the most important part of the reproducing head (thin film magnetic head). First, the gap layer is formed on the lower shield layer made of a magnetic material. After that, the spin-valve type thin film element is formed. After that, when an upper shield layer is formed on the spin-valve type thin film element via a gap layer,
A reproducing head (MR head) is completed. A recording inductive head having a magnetic material core and a coil may be laminated on the reproducing head. In this case, it is preferable that the upper shield layer also serves as the lower core layer of the inductive head. The spin-valve type thin film element after FIG. 3 has shield layers formed above and below the spin-valve type thin-film element shown in FIG.

FIG. 3 is a transverse sectional view schematically showing the structure of the spin-valve type thin film element according to the second embodiment of the present invention,
FIG. 4 is a cross-sectional view of the spin-valve type thin film element shown in FIG. 3 viewed from the side facing the recording medium.

This spin valve thin film element is a single spin valve thin film element formed by reversing the film structure of the spin valve thin film element of FIG.

That is, in the spin-valve type thin film element shown in FIG. 3, the underlayer 10, the NiFe film 22, the Co film 23 (the free magnetic layer 21 including the NiFe film 22 and the Co film 23 together), the nonmagnetic conductive layer are arranged from the bottom. 24, second pinned magnetic layer 2
5, the nonmagnetic intermediate layer 26, the first pinned magnetic layer 27, the antiferromagnetic layer 28, and the protective layer 29 are stacked in this order.

The antiferromagnetic layer 28 is preferably made of a PtMn alloy, or instead of the PtMn alloy, X-Mn (where X is Pd, Ir, R).
h or Ru, which is one or more elements)
Alloy or Pt-Mn-X '(where X'is P
d, Ir, Rh, Ru, Au, Ag, which is one kind or two or more kinds of elements).

Also in this spin valve type thin film element,
The film thickness t of the first pinned magnetic layer 27 _P1And the second fixed magnet
Ratio t of the conductive layer 25_P2Is (the film thickness t of the first pinned magnetic layer).
_P1) / (Thickness t of the second pinned magnetic layer)_P2) Is 0.33 ~
Within the range of 0.95, or 1.05-4
Preferably, more preferably 0.53 to 0.95
Or within the range of 1.05 to 1.8. Moreover, the first
The film thickness t of the pinned magnetic layer 27_P1And the second pinned magnetic layer 25
Film thickness t_P2Within the range of 10 to 70 Å, and
The thickness t of the first pinned magnetic layer 27_P1To the second fixed magnetism
Film thickness t of layer 25 _P2The absolute value of minus is 2 angstrom
The above is preferable. More preferably, the first
The film thickness t of the pinned magnetic layer 27_P1And the second pinned magnetic layer 25
Film thickness t_P2Within the range of 10 to 50 Å, and
The thickness t of the first pinned magnetic layer 27 _P1To the second fixed magnetism
Film thickness t of layer 25_P2The absolute value of minus is 2 angstrom
That is all.

As described above, unless there is a certain difference in the magnetic film thickness between the first pinned magnetic layer 27 and the second pinned magnetic layer 25, the magnetization state is unlikely to be the ferri state, and the first pinned magnetic layer is not formed. If the difference in the magnetic film thickness between the magnetic layer 27 and the second pinned magnetic layer 25 becomes too large, the exchange coupling magnetic field will decrease, which is not preferable. Therefore, in the present invention, in the same manner as the film thickness ratio of the first pinned magnetic layer 27 and the second pinned magnetic layer 25,
(Magnetic film thickness Ms · t _{P1 of} the first pinned magnetic layer 27) /
(The magnetic film thickness Ms · t _{P2 of} the second pinned magnetic layer 25) is
It is preferably within the range of 0.33 to 0.95, or 1.05 to 4. In the present invention also the magnetic film thickness Ms · t _P2 of the magnetic film thickness Ms · t _P1 and the second fixed magnetic layer 25 of the first fixed magnetic layer 27 in the range of 10 to 70 (Å Tesla) And the first pinned magnetic layer 2
It is preferable that the absolute value obtained by subtracting the magnetic film thickness Ms · t _P2 of the second pinned magnetic layer 25 from the magnetic film thickness Ms · t _{P1 of} 7 is 2 (angstrom tesla) or more.

Further, (magnetic film thickness Ms · t _{P1 of} first pinned magnetic layer 27) / (magnetic film thickness M of second pinned magnetic layer 25)
s · t _P2 ) is 0.53 to 0.95, or 1.05
More preferably, it is within the range of -1.8. Within the above range, the magnetic film thickness M of the first pinned magnetic layer 27 is
s · t _P1 and the magnetic film thickness Ms · t of the second pinned magnetic layer 25.
Both _P2 are in the range of 10 to 50 (angstrom tesla), and moreover, the magnetic film thickness Ms · t _{P1 of} the first pinned magnetic layer 27 to the magnetic film thickness Ms of the second pinned magnetic layer 25.
The absolute value obtained by subtracting t _P2 is preferably 2 (angstrom tesla) or more.

Next, the non-magnetic intermediate layer 26 interposed between the first pinned magnetic layer 27 and the second pinned magnetic layer 25 shown in FIG.
Is preferably formed of an alloy of one or more of Ru, Rh, Ir, Cr, Re and Cu.

In the present invention, as shown in FIG. 3, when the antiferromagnetic layer 28 is formed above the free magnetic layer 21, the thickness of the nonmagnetic intermediate layer 26 is 2.5 to 6. It is preferably in the range of 4 angstroms or 6.6 to 10.7 angstroms. Within this range, an exchange coupling magnetic field (Hex) of at least 500 (Oe) can be obtained.

In the present invention, the film thickness of the non-magnetic intermediate layer 26 is more preferably within the range of 2.8 to 6.2 angstroms or 6.8 to 10.3 angstroms. Within this range, at least 10
It is possible to obtain an exchange coupling magnetic field of 00 (Oe) or more.

At least 9% of the antiferromagnetic layer 28 is formed.
500 (Oe) if formed above 0 angstrom
It is possible to obtain the above exchange coupling magnetic field. If the film thickness is 100 angstroms or more, 1000
It is possible to obtain an exchange coupling magnetic field of (Oe) or more.

In the spin valve thin film element shown in FIG.
The film thickness t _P1 of the first pinned magnetic layer 27 is formed to be different from the film thickness t _{P2 of} the second pinned magnetic layer 25.
The film thickness t _P1 of the pinned magnetic layer 27 is thicker than the film thickness t _{P2 of} the second pinned magnetic layer 25. Further, the magnetization of the first pinned magnetic layer 27 is magnetized in the Y direction in the drawing,
The magnetization of the second pinned magnetic layer 25 is magnetized in the direction opposite to the Y direction in the figure, and the magnetizations of the first pinned magnetic layer 27 and the second pinned magnetic layer 25 are in a ferri state. A method of controlling the magnetization directions of the first pinned magnetic layer 27 and the second pinned magnetic layer 25 shown in FIG. 3 will be described below.

First, each layer shown in FIG. 3 is formed by a sputtering method or the like, and annealing (heat treatment) is performed in a magnetic field in a step after the film formation.

The Ms · t _P1 (magnetic moment) of the first pinned magnetic layer 27 is the Ms · t of the second pinned magnetic layer 25.
If it is larger than _P2 (magnetic moment),
100 to 10 in the direction in which the magnetization of the pinned magnetic layer 27 of
A magnetic field of 00 (Oe) or 5k (Oe) may be applied.

As shown in FIG. 3, when the first pinned magnetic layer 27 having a large Ms · t _P1 is oriented in the Y direction in the drawing,
By referring to the above-mentioned Table 1, 10 in the Y direction in the figure.
0-1k (Oe) (see Table 1 (2)) or Y shown
A magnetic field of 5 k (Oe) or more (see Table 1 (3)) is applied in the direction during heat treatment.

By applying a magnetic field of 100 to 1 k (Oe) in the Y direction shown, the magnetization of the first pinned magnetic layer 27 having a large Ms · t _P1 is oriented in the Y direction shown and the second pinned magnetic layer 25 Magnetization tends to become antiparallel. Then, the magnetization of the first pinned magnetic layer 27 is pinned in the Y direction in the figure by the exchange coupling magnetic field (exchange anisotropic magnetic field) generated at the interface between the first pinned magnetic layer 27 and the antiferromagnetic layer 28. Is
As a result, the magnetization of the second pinned magnetic layer 25 is pinned in the direction opposite to the Y direction in the figure.

Alternatively, when a magnetic field of 5 k (Oe) or more is applied in the Y direction in the figure, a magnetic field larger than the exchange coupling magnetic field (RKKY interaction) generated between the first pinned magnetic layer 27 and the second pinned magnetic layer 25. Is applied, both the magnetizations of the first pinned magnetic layer 27 and the second pinned magnetic layer 25 are magnetized in the Y direction in the drawing, and the magnetization of the first pinned magnetic layer 27 is antiferromagnetic layer 28. It is fixed in the Y direction in the figure by the exchange coupling magnetic field (exchange anisotropic magnetic field) generated at the interface with.
On the other hand, the magnetization of the second pinned magnetic layer 25 is reversed by the exchange coupling magnetic field (RKKY interaction) with the first pinned magnetic layer 27 by removing the applied magnetic field, and the magnetization of the first pinned magnetic layer 27 is reversed. It is fixed in an antiparallel state with the magnetization.

Alternatively, when the magnetic moment of the first pinned magnetic layer 27 is smaller than the magnetic moment of the second pinned magnetic layer 25, the direction of magnetization of the first pinned magnetic layer 27 is opposite to the desired direction. A magnetic field of 100 to 1000 (Oe) is applied, or a magnetic field of 5 k (Oe) or more is applied in the direction in which the magnetization is desired to be directed.

As shown in FIG. 4, the hard bias layer 1 is formed on both sides of the laminated body from the underlayer 10 to the protective layer 29.
30 and the conductive layer 131 are formed, and the hard bias layer 130 is magnetized in the X direction in the figure, so that the magnetization of the free magnetic layer 21 is aligned in the X direction in the figure.

FIG. 5 is a cross sectional view schematically showing the structure of the spin-valve type thin film element according to the third embodiment of the present invention,
FIG. 6 is a cross-sectional view of the spin-valve type thin film element shown in FIG. 5 viewed from the side facing the recording medium.

This spin-valve thin-film element is a so-called dual spin-valve thin-film element in which a nonmagnetic conductive layer, a pinned magnetic layer, and an antiferromagnetic layer are formed one layer above and below a free magnetic layer as a center. is there. In this dual spin valve thin film element, since there are two combinations of these three layers of the free magnetic layer / nonmagnetic conductive layer / fixed magnetic layer, there is a large ΔM compared to the single spin valve thin film element.
R can be expected, and high density recording can be achieved.

The spin-valve type thin film element shown in FIG. 5 includes a base layer 30, an antiferromagnetic layer 31, a first pinned magnetic layer (bottom) 32, a non-magnetic intermediate layer (bottom) 33, and a second pinned layer from the bottom. Magnetic layer (bottom) 34, non-magnetic conductive layer 35, free magnetic layer 36
(Reference numerals 37 and 39 are Co films, reference numeral 38 is a NiFe alloy film), non-magnetic conductive layer 40, second fixed magnetic layer (upper) 4
1, non-magnetic intermediate layer (top) 42, first pinned magnetic layer (top)
43, the antiferromagnetic layer 44, and the protective layer 45 are stacked in this order. As shown in FIG. 6, the hard bias layer 130 is formed on both sides of the laminated body from the base layer 30 to the protective layer 45.
And a conductive layer 131 is formed.

The antiferromagnetic layers 31, 44 of the spin-valve type thin film element shown in FIG. 5 are preferably formed of PtMn alloy, or instead of PtMn alloy, X--M
n (where X is any one of Pd, Ir, Rh, Ru)
Alloy of two or more elements) or Pt
-Mn-X '(where X'is Pd, Ir, Rh, R
u, Au, Ag, which is one kind or two or more kinds of elements) alloy.

Also in this spin valve type thin film element,
Said first and thickness t _P1 of the fixed magnetic layer (lower) 32, the thickness ratio between the film thickness t _P2 of the second pinned magnetic layer (lower) 34, and first
Thickness ratio between the film thickness t _P2 of the fixed magnetic layer (upper) 43 and the film thickness t _P1 of the second pinned magnetic layer 41 (top) (first film thickness t _P1 of the fixed magnetic layer) / (a The thickness t _P2 of the pinned magnetic layer of No. 2 is 0.
It is preferably within the range of 33 to 0.95, or 1.05 to 4. Further, the film thickness ratio is within the above range, and the film thickness t of the first pinned magnetic layers (bottom) 32 and (top) 43 is t.
The film thickness t _{P2 of P1} and the second pinned magnetic layers (lower) 34, (upper) 41 is in the range of 10 to 70 angstroms, and the film thickness t _{P1 of} the first pinned magnetic layers 32, 43 from the second If the absolute value obtained by subtracting the film thickness t _P2 of the pinned magnetic layers 34 and 41 is 2 angstroms or more, it is possible to obtain an exchange coupling magnetic field of 500 (Oe) or more.

In the present invention, (thickness t _P1 of first pinned magnetic layer) / (thickness t _P2 of second pinned magnetic layer) is 0.5.
It is more preferable that the thickness is in the range of 3 to 0.95, or 1.05 to 1.8, and further, the film thickness t _{P1 of} the first pinned magnetic layer (lower) 32 and (upper) 43 and the second the fixed magnetic layer (lower) 34, a thickness t _P2 (upper) 41 in the range of 10 to 50 angstroms, and the first fixed magnetic layer 32,
If the absolute value obtained by subtracting the film thickness t _P2 of the second pinned magnetic layers 34 and 41 from the film thickness t _{P1 of} 43 is 2 Å or more, an exchange coupling magnetic field of 1000 (Oe) or more can be obtained.

By the way, the film thickness t _{P1 of} the first pinned magnetic layer (lower) 32 formed below the free magnetic layer 36.
_Is larger than the film thickness t _{P2 of} the second pinned magnetic layer (bottom) 34, the film thickness t _{P1 of} the first pinned magnetic layer (bottom) 32 is
It has been confirmed by experiments that the exchange coupling magnetic field tends to decrease when the film thickness difference between the second pinned magnetic layer (lower) 34 and the second pinned magnetic layer (lower) 34 is about 6 angstroms or less.

This phenomenon occurs in the first pinned magnetic layer (bottom) 3
2, (top) requires heat treatment to generate an exchange coupling magnetic field (exchange anisotropic magnetic field) at the interface with 43, for example, P
It is observed when the antiferromagnetic layers 31 and 44 formed of tMn alloy are used.

The decrease in the exchange coupling magnetic field is caused by the free magnetic layer 36.
The magnetic thickness of the first pinned magnetic layer (lower) 32 is reduced by thermal diffusion between the antiferromagnetic layer 31 and the first pinned magnetic layer (lower) 32 which are formed on the lower side. And the first
This is because the magnetic film thickness of the pinned magnetic layer (lower) 32 and the film thickness t _{P2 of} the second pinned magnetic layer 34 are substantially the same. Therefore, in the present invention, (the first pinned magnetic layer (upper)
Thickness t _{P1 of} 43 / thickness t of the second pinned magnetic layer (upper) 41
( _P2 ) (thickness of first pinned magnetic layer (lower) 32 t _P1 /
It is preferable to increase the thickness t _{P2 of} the second pinned magnetic layer (lower) 34.

The generation of the thermal diffusion layer is not limited to the dual spin valve type thin film element shown in FIG. 5, but a single spin valve type thin film element in which the antiferromagnetic layer 11 is formed below the free magnetic layer 16. (See FIG. 1) is a similar phenomenon.

As described above, the first pinned magnetic layer (bottom)
32, (upper) 43 magnetic film thickness Ms · t _P1 and second pinned magnetic layer (lower) 34, (upper) magnetic film thickness Ms · t _P2
If there is no difference between the two, the magnetization state is unlikely to be a ferri state, and the first pinned magnetic layers (bottom) 32, (top) 43
Magnetic film thickness Ms · t _P1 and the second pinned magnetic layer (bottom) 3
If the difference in the magnetic film thickness Ms · t _P2 of 4, (upper) 41 becomes too large, the exchange coupling magnetic field is lowered, which is not preferable. Therefore, in the present invention, the first pinned magnetic layer (lower) 32,
(Top) 43 thickness t _P1 and second pinned magnetic layer (bottom) 34,
Similar to the film thickness ratio of the film thickness t _P2 of (upper) 41, (the magnetic film thickness Ms. of the first pinned magnetic layer (lower) 32, (upper) 43)
t _P1 ) / (the magnetic film thickness Ms · t _{P2 of} the second pinned magnetic layer (lower) 34, (upper) 41) is in the range of 0.33 to 0.95, or 1.05 to 4 Is preferred. Further, in the present invention, the first fixed magnetic layer (lower) 32, (upper) 4
3 magnetic thickness Ms · t _P1 and second pinned magnetic layer (bottom)
34, (upper) 41 has a magnetic film thickness Ms · t _P2 of 10 to 70
Within the range of (Angstrom Tesla), and the magnetic film thickness Ms of the first fixed magnetic layers (lower) 32, (upper) 43
It is preferable that the absolute value obtained by subtracting the magnetic film thickness Ms · t _P2 of the second pinned magnetic layers (lower) 34, (upper) 41 from t _P1 is 2 (angstrom tesla) or more.

In addition, (the first pinned magnetic layer (lower) 32,
(Upper) magnetic film thickness Ms · t _{P1 of} 43 / (second fixed magnetic layer (lower) 34, (upper) magnetic film thickness Ms · t _P2 ) 41
Is more preferably in the range of 0.53 to 0.95, or 1.05 to 1.8. Within the above range, the magnetic film thickness Ms · t _{P1 of} the first pinned magnetic layer (bottom) 32, (top) 43 and the second pinned magnetic layer (bottom) 34,
(Top) The magnetic film thickness Ms · t _P2 of 41 is both 10 to 50
Within the range of (angstrom tesla), and moreover, from the magnetic film thickness Ms · t _{P1 of} the first pinned magnetic layer (bottom) 32, (top) 43 to the second pinned magnetic layer (bottom) 34, (top) ) 4
The absolute value obtained by subtracting the magnetic film thickness Ms · t _P2 of 1 is preferably 2 (angstrom tesla) or more.

Next, the first pinned magnetic layer (bottom) 3 shown in FIG.
2, (top) 43 and second pinned magnetic layer (bottom) 34, (top)
The non-magnetic intermediate layers 33 and 42 interposed between the
It is preferable to be formed of an alloy of one or more of u, Rh, Ir, Cr, Re and Cu.

As shown in FIG. 5, the film thickness of the non-magnetic intermediate layer (lower) 33 formed below the free magnetic layer 36 is in the range of 3.6 to 9.6 angstroms. It is preferable. Within this range, 500 (O
It is possible to obtain the exchange coupling magnetic field (Hex) above e).

If the thickness of the nonmagnetic intermediate layer (lower) 33 is in the range of 4 to 9.4 angstroms, an exchange coupling magnetic field of 1000 (Oe) or more can be obtained, which is more preferable. .

In the present invention, as shown in FIG. 5, the nonmagnetic intermediate layer (upper) formed above the free magnetic layer 36.
The film thickness of 42 is preferably in the range of 2.5 to 6.4 angstroms, or 6.8 to 10.7 angstroms. Within this range, at least 50
An exchange coupling magnetic field (Hex) of 0 (Oe) or more can be obtained.

In the present invention, the nonmagnetic intermediate layer (upper)
The film thickness of 42 is more preferably in the range of 2.8 to 6.2 angstroms or 6.8 to 10.3 angstroms. Within this range, it is possible to obtain an exchange coupling magnetic field of at least 1000 (Oe) or more.

If the antiferromagnetic layers 31 and 44 are formed to have a thickness of at least 100 Å, then 500
It is possible to obtain an exchange coupling magnetic field of (Oe) or more.
If the film thickness is 110 angstroms or more,
It is possible to obtain an exchange coupling magnetic field of 1000 (Oe) or more.

Conventionally, the antiferromagnetic layers 31 and 44 are formed to have a thickness of about 200 Å or more. Therefore, according to the present invention, the antiferromagnetic layer 3 has a thickness of about half.
1, 44 can be formed, and particularly in the case of a dual spin valve type thin film element, the antiferromagnetic layers 31, 4 can be formed.
Since two layers of No. 4 are formed, the film thickness of the entire spin-valve type thin film element can be reduced by about 200 angstroms or more as compared with the conventional one. In the spin-valve type thin film element thus formed, the gap length Gl can be reduced even if the lower gap layer 121 and the upper gap layer 125 shown in FIG. 13 are thick enough to maintain sufficient insulation. It is compatible with high density recording.

The first pinned magnetic layers (bottom) 32, (top)
43 and the second pinned magnetic layer (lower) 34, (upper) 41, the film thickness ratio of the non-magnetic intermediate layer (lower) 33, (upper) 42, and the antiferromagnetic layer 31, By properly adjusting the film thickness of 44 within the above-mentioned range, it is possible to maintain the same ΔMR as in the conventional case, and specifically, it is possible to obtain ΔMR of about 10% or more.

As shown in FIG. 5, the film thickness t _P1 of the first pinned magnetic layer (lower) 32 formed below the free magnetic layer 36 is formed via the non-magnetic intermediate layer 33. It is formed thinner than the film thickness t _P2 of the second pinned magnetic layer (lower) 34. On the other hand, the film thickness t _P1 of the first pinned magnetic layer (upper) 43 formed above the free magnetic layer 36 is equal to the second pinned magnetic layer 41 formed via the non-magnetic intermediate layer 42.
It is formed thicker than the film thickness t _P2 in (top). And
The magnetizations of the first pinned magnetic layers (bottom) 32 and (top) 43 are both magnetized in the direction opposite to the Y direction in the figure, and the magnetizations of the second pinned magnetic layers (bottom) 34 and (top) 41 are shown. It is magnetized in the Y direction.

In the case of the single spin valve thin film element shown in FIGS. 1 and 3, Ms of the first pinned magnetic layer is
The film thickness is adjusted so that t _P1 is different from Ms · t _{P2 of} the second pinned magnetic layer, and the magnetization direction of the first pinned magnetic layer is
Either the Y direction shown or the opposite direction to the Y direction shown may be used.

However, in the dual spin-valve type thin film element shown in FIG. 5, the first pinned magnetic layer (lower) 32,
It is necessary that the magnetizations of the (upper) 43 be oriented in the same direction. Therefore, in the present invention, the magnetic moments Ms · t of the first pinned magnetic layers (lower) 32 and (upper) 43 are set.
_P1 and the magnetic moment Ms · t _{P2 of} the second fixed magnetic layers (lower) 34 and (upper) 41 are adjusted, and the direction and magnitude of the magnetic field applied during the heat treatment are appropriately adjusted.

Here, the first pinned magnetic layer (lower) 32,
The magnetizations of the (upper) 43 are oriented in the same direction so that the magnetizations of the first fixed magnetic layer (lower) 32 and (upper) 43 are anti-parallel to the second fixed magnetic layer (lower) 34. , (Upper) 41 are oriented in the same direction, and the reason for this will be described below.

As described above, the ΔMR of the spin-valve type thin film element is obtained by the relationship between the fixed magnetization of the fixed magnetic layer and the variable magnetization of the free magnetic layer. In the case of being divided into two layers, the first pinned magnetic layer and the second pinned magnetic layer, the layer of the pinned magnetic layer directly involved in ΔMR is the second pinned magnetic layer, and The pinned magnetic layer plays a so-called auxiliary role for pinning the magnetization of the second pinned magnetic layer in a fixed direction.

The second pinned magnetic layer (bottom) 3 shown in FIG.
Assuming that the magnetizations of 4 and (upper) 41 are fixed in mutually opposite directions, for example, the fixed magnetization of the second fixed magnetic layer (upper) 41 and the variable magnetization of the free magnetic layer 36 have a large resistance. Even so, the resistance becomes extremely small due to the relationship between the fixed magnetization of the second fixed magnetic layer (lower) 34 and the variable magnetization of the free magnetic layer 36, and as a result, ΔMR in the dual spin valve thin film element is However, it becomes smaller than ΔMR of the single spin valve thin film element shown in FIGS. 1 and 3.

This problem is not limited to the dual spin-valve type thin film element in which the pinned magnetic layer is divided into two layers via the non-magnetic intermediate layer as in the present invention, but the conventional dual spin-valve type thin film element. But the same is true,
In order to exert the characteristics of the dual spin valve type thin film element capable of increasing ΔMR and obtaining a large output as compared with the single spin valve type thin film element, the pinned magnetic layers formed above and below the free magnetic layer should have the same direction. Need to be fixed to.

By the way, in the present invention, as shown in FIG.
In the pinned magnetic layer formed below the free magnetic layer 36, Ms · t _P2 of the second pinned magnetic layer (lower) 34 is
The magnetization of the second pinned magnetic layer (bottom) 34, which is larger than Ms · t _P1 of the first pinned magnetic layer (bottom) 32 and has a large Ms · t _P2 , is pinned in the Y direction in the figure. Here, a so-called combined magnetic moment obtained by adding Ms · t _{P2 of} the second pinned magnetic layer 34 and Ms · t _{P1 of} the first pinned magnetic layer 32 is the second Ms · t _{P2 having} a large value. It is dominated by the magnetic moment of the pinned magnetic layer 34 and is oriented in the Y direction in the figure.

On the other hand, the pinned magnetic layer formed above the free magnetic layer 36 is M of the first pinned magnetic layer (upper) 43.
s · t _P1 is the Ms · of the second pinned magnetic layer (upper) 41
The magnetization of the first pinned magnetic layer (upper) 43, which is larger than t _P2 and has a large Ms · t _P1 , is pinned in the direction opposite to the Y direction in the figure. M of the first pinned magnetic layer (upper) 43
s · t _P1 and Ms · t _{P2 of} the second pinned magnetic layer (upper) 41
The so-called combined magnetic moment, which is obtained by adding and, is dominated by Ms · t _P1 of the first fixed magnetic layer (upper) 43, and is directed in the direction opposite to the Y direction in the figure.

That is, in the dual spin-valve type thin film element shown in FIG. 5, Ms · t _{P1 of} the first pinned magnetic layer and Ms · t of the second pinned magnetic layer are formed above and below the free magnetic layer 36.
The direction of the synthetic magnetic moment that can be obtained by adding _P2 is the opposite direction. Therefore, the combined magnetic moment formed below the free magnetic layer 36 in the Y direction in the drawing and the combined magnetic moment formed above the free magnetic layer 36 in the opposite direction to the Y direction in the drawing. The moment forms a magnetic field around the left side in the drawing.

Therefore, the magnetic field formed by the composite magnetic moment causes the first pinned magnetic layer (lower) 32,
(Upper) 43 magnetization and second pinned magnetic layer (lower) 34,
It is possible to maintain a more stable ferri state with the magnetization of (upper) 41.

Further, the sense current 114 mainly flows through the non-magnetic conductive layers 35 and 39 having a small specific resistance, and the sense current 114 is caused to flow, whereby a sense current magnetic field is formed by the right-handed screw law. However, by flowing the sense current 114 in the direction of FIG.
6, the direction of the sense current magnetic field formed by the sense current at the location of the first pinned magnetic layer (lower) 32 / non-magnetic intermediate layer (lower) 33 / second pinned magnetic layer (lower) 34 formed on the lower side of 6. The first pinned magnetic layer (bottom) 32 / non-magnetic intermediate layer (bottom) 33
/ The direction of the synthetic magnetic moment of the second pinned magnetic layer (lower) 34 can be made to coincide with the free magnetic layer 3
First pinned magnetic layer (upper) 43 formed above 6
/ Non-magnetic intermediate layer (upper) 42 / Second pinned magnetic layer (upper) 4
The sense current magnetic field generated by the sense current at the position 1 is set to the first pinned magnetic layer (upper) 43 / nonmagnetic intermediate layer (upper) 42 /
The direction of the synthetic magnetic moment of the second pinned magnetic layer (upper) 41 can be matched.

The merit of matching the direction of the sense current magnetic field with the direction of the synthetic magnetic moment will be described in detail later, but simply stated, it is possible to enhance the thermal stability of the pinned magnetic layer. Since a large sense current can be passed, there is a great merit that the reproduction output can be improved. The relationship between the sense current magnetic field and the direction of the combined magnetic moment is that the combined magnetic moments of the fixed magnetic layers formed above and below the free magnetic layer 36 form the counterclockwise magnetic field in the figure.

The environmental temperature in the apparatus rises to about 200 ° C., and in the future, the environmental temperature tends to further increase due to the number of rotations of the recording medium and the sense current. When the ambient temperature rises in this way, the exchange coupling magnetic field decreases, but according to the present invention, the first fixed magnetic field is thermally stable due to the magnetic field formed by the synthetic magnetic moment and the sense current magnetic field. The magnetizations of the layers (lower) 32 and (upper) 43 and the magnetizations of the second pinned magnetic layers (lower) 34 and (upper) 41 can be kept in a ferri state.

The above-described formation of the magnetic field due to the synthetic magnetic moment and the directional relationship between the magnetic field due to the synthetic magnetic moment and the sense current magnetic field are configurations peculiar to the present invention, and are formed as a single layer above and below the free magnetic layer. Moreover, it cannot be obtained with the conventional dual spin-valve type thin film element having the fixed magnetic layer which is oriented in the same direction and is fixedly magnetized.

Next, the direction and magnitude of the magnetic field applied during the heat treatment will be described below. In the spin-valve type thin film element shown in FIG. 5, PtMn is formed in the antiferromagnetic layers 31 and 44.
An antiferromagnetic material that requires heat treatment is used to generate an exchange coupling magnetic field (exchange anisotropic magnetic field) at the interface with the first pinned magnetic layers (lower) 32 and (upper) 43 such as an alloy. Therefore, unless the direction and magnitude of the magnetic field applied during the heat treatment are properly controlled, the first pinned magnetic layer (lower) 32,
(Upper) 43 and second pinned magnetic layers (lower) 34, (upper) 41
The magnetization directions of and cannot be obtained in the directions shown in FIG.

First, at the stage of film formation, as shown in FIG.
The Ms · t _P1 of the first pinned magnetic layer (lower) 32 formed below the free magnetic layer 36 is made smaller than the Ms · t _{P2 of} the second pinned magnetic layer (lower) 34, and The Ms · t _P1 of the first pinned magnetic layer (upper) 43 formed above the free magnetic layer 36 is set to the second pinned magnetic layer (upper) 41.
It is larger than Ms · t _{P2 of} .

As shown in FIG. 5, when it is desired to orient the first pinned magnetic layers (lower) 32, (upper) 43 in the direction opposite to the Y direction in the drawing, refer to Tables 1 and 2 described above. , 5k (Oe) or more in the direction opposite to the Y direction in the figure (Table 1
It is necessary to apply the magnetic field of (4) and Table 2 (4)).

By applying a magnetic field of 5 k (Oe) or more in the direction opposite to the Y direction in the figure, the first pinned magnetic layer (bottom)
32, (top) magnetization of 43 and second pinned magnetic layer (bottom) 3
The magnetizations of 4 and (upper) 41 are once oriented in the direction opposite to the Y direction in the figure. The first pinned magnetic layers (bottom) 32, (top) 4
3 is fixed in the direction opposite to the Y direction in the drawing by the exchange coupling magnetic field (exchange anisotropic magnetic field) at the interface with the antiferromagnetic layers 31 and 44, and the magnetic field of 5 k (Oe) or more is removed, The magnetizations of the second pinned magnetic layers (lower) 34 and (upper) 41 are reversed in the Y direction in the figure by the exchange coupling magnetic field (RKKY interaction) with the first pinned magnetic layers (lower) 32 and (upper) 43. Then, it is fixed in the Y direction in the figure.

Alternatively, a magnetic field of 5 k (Oe) or more is shown Y
It may be given in the direction. In this case, the magnetizations of the first pinned magnetic layers (bottom) 32 and (top) 43 and the magnetizations of the second pinned magnetic layers (bottom) 34 and (top) 41 are opposite to the magnetization directions shown in FIG. Is magnetized to form a magnetic field due to the clockwise synthetic magnetic moment.

Further, in the present invention, Ms · of the first pinned magnetic layer (lower) 32 formed below the free magnetic layer 36.
t _P1 is set to be larger than Ms · t _{P2 of} the second pinned magnetic layer 34, and Ms · t _P1 of the first pinned magnetic layer 43 formed above the free magnetic layer 36 is set to be second. The fixed magnetic layer 41 may be smaller than Ms · t _P2 . Also in this case, the first pinned magnetic layers (bottom) 32, (top) 4
By applying a magnetic field of 5 k (Oe) or more in the direction desired to obtain the magnetization of 3, that is, in the Y direction in the drawing or in the direction opposite to the Y direction in the drawing, the second pinned magnetic layers formed above and below the free magnetic layer 36 ( The lower) 34 and the (upper) 41 can be fixed in the same direction, and a magnetic field can be formed by a clockwise or counterclockwise combined magnetic moment in the drawing.

The second pinned magnetic layer (bottom) 3 formed above and below the free magnetic layer 36 by a method other than the above-mentioned method.
It is not possible to direct the magnetizations of 4, (upper) 41 to the same direction, and to form a magnetic field by the combined magnetic moment and a directional relationship between the magnetic field by the combined magnetic moment and the sense current magnetic field.

In the present invention, the following method is used.
The magnetizations of the second pinned magnetic layers (lower) 34 and (upper) 41 can be oriented in the same direction, but the combined magnetic moments formed above and below the free magnetic layer 36 are oriented in the same direction. However, it is not possible to form a magnetic field by the synthetic magnetic moment. However, with the dual spin-valve type thin film element of the present invention, it is possible to obtain the same ΔMR as that of the conventional dual spin-valve type thin film element by the following heat treatment method, and moreover, the conventional dual spin-valve type thin film element. Compared with the above, it is possible to keep the magnetization state of the pinned magnetic layers (the first pinned magnetic layer and the second pinned magnetic layer) in a thermally stable state.

First, Ms · t _{P1 of} the first pinned magnetic layer (bottom) 32 formed below the free magnetic layer 36 and the first pinned magnetic layer (top) formed above the free magnetic layer 36 ( When both Ms · t _P1 of the upper part 43 are larger than Ms · t _{P2 of} the second pinned magnetic layer (bottom) 34 and (upper) 41, the first pinned magnetic layer (bottom) 32 is , (Above) 4
By applying a magnetic field of 100 to 1 k (Oe) or 5 k (Oe) or more in the direction in which the magnetization of 3 is desired, the first pinned magnetic layers (lower) 32 and (upper) 43 are both directed in the same direction. The first pinned magnetic layer (bottom) 32, (top)
By the exchange coupling magnetic field (RKKY interaction) with 43,
A second pinned magnetic layer (bottom) 34 magnetized antiparallel to the magnetization of the first pinned magnetic layer (bottom) 32, (top) 43,
The magnetizations of (upper) 41 can be fixed in the same direction.

Alternatively, Ms · t _{P1 of} the first pinned magnetic layer (bottom) 32 formed below the free magnetic layer 36 and the first pinned magnetic layer (top) formed above the free magnetic layer 36 ( When both Ms · t _P1 of the upper part 43 are smaller than Ms · t _{P2 of} the second pinned magnetic layer (bottom) 34 and (upper) 41, the first pinned magnetic layer (bottom) 32 , (Above) 4
100 to 1k in the direction opposite to the direction in which the magnetization of 3 is desired
(Oe), or the first pinned magnetic layer (bottom) 3
2, (top) by applying a magnetic field of 5 k (Oe) or more in the direction in which the magnetization of 43 is directed, the first pinned magnetic layer (bottom)
32 and (upper) 43 are oriented in the same direction, and an exchange coupling magnetic field (R) with the first fixed magnetic layer (lower) 32 and (upper) 43 is set.
(KKY interaction) causes the magnetizations of the first pinned magnetic layers (bottom) 32 and (top) 43 to be antiparallel to the magnetizations of the second pinned magnetic layers (bottom) 34 and (top) 41. It can be fixed in the same direction.

As described above, according to the spin-valve type thin film element shown in FIGS. 1 to 6, the pinned magnetic layer is the two layers of the first pinned magnetic layer and the second pinned magnetic layer with the nonmagnetic intermediate layer interposed therebetween. And the magnetization of the two pinned magnetic layers is made antiparallel to each other by the exchange coupling magnetic field (RKKY interaction) generated between the two pinned magnetic layers. The stable magnetization state of the pinned magnetic layer can be maintained.

In the present invention, in particular, a PtMn alloy that has a very high blocking temperature as the antiferromagnetic layer and generates a large exchange coupling magnetic field (exchange anisotropic magnetic field) at the interface with the first pinned magnetic layer is used. As a result, the magnetization states of the first pinned magnetic layer and the second pinned magnetic layer can be made more excellent in thermal stability.

In the present invention, the first pinned magnetic layer and the second pinned magnetic layer are used.
The film thickness ratio to the pinned magnetic layer, the film thickness of the non-magnetic intermediate layer interposed between the first pinned magnetic layer and the second pinned magnetic layer,
By forming the film thickness of the antiferromagnetic layer within an appropriate range, the exchange coupling magnetic field (Hex) can be increased, and therefore the heat of the fixed magnetization of the first pinned magnetic layer and the second pinned magnetic layer can be increased. It is possible to further improve the physical stability.

The film thickness ratio of the film thickness t _P1 of the first pinned magnetic layer to the film thickness t _{P2 of} the second pinned magnetic layer, and further,
By forming the pinned magnetic layer, the second pinned magnetic layer, the non-magnetic intermediate layer, and the antiferromagnetic layer within the appropriate ranges, it is possible to obtain ΔMR that is almost the same as the conventional one. .

Further, in the present invention, Pt is used as the antiferromagnetic layer.
When an antiferromagnetic material such as a Mn alloy that requires heat treatment to generate an exchange coupling magnetic field (exchange anisotropic magnetic field) at the interface with the first pinned magnetic layer is used, the first pinned magnetic layer Ms · t _P1 of the second fixed magnetic layer and Ms · t _{P2 of} the second fixed magnetic layer are formed to have different values, and the magnitude and direction of the applied magnetic field during the heat treatment are appropriately adjusted to thereby provide the first fixed magnetic layer. It is possible to magnetize the magnetic layer (and the second pinned magnetic layer) in the desired direction.

Particularly in the dual spin-valve type thin film element shown in FIG. 5, the first pinned magnetic layer (lower) 32,
(Top) 43 Ms · t _P1 and second pinned magnetic layer (bottom) 3
4, (upper) 41 by appropriately adjusting Ms · t _P2 , and by further adjusting the magnitude and direction of the applied magnetic field during the heat treatment, the free magnetic layer 36 formed above and below ΔMR is formed. Two second pinned magnetic layers (bottom) 34,
The magnetizations of (upper) 41 can be fixed in the same direction, and the combined magnetic moments formed above and below the free magnetic layer 36 can be formed in opposite directions, thereby forming a magnetic field by the combined magnetic moment, and It is possible to form a directional relationship between the magnetic field due to the magnetic moment and the sense current magnetic field, and it is possible to further improve the thermal stability of the magnetization of the pinned magnetic layer.

FIG. 7 is a transverse sectional view schematically showing the structure of the spin-valve type thin film element according to the fourth embodiment of the present invention,
FIG. 8 is a cross-sectional view of the spin-valve type thin film element shown in FIG. 7 when viewed from the surface facing the recording medium.

Also in this spin valve type thin film element,
Similar to the spin-valve type thin film element shown in FIGS. 1 to 6, it is provided at the trailing side end of a flying slider provided in a hard disk device and detects the recording magnetic field of the hard disk. The moving direction of the magnetic recording medium such as a hard disk is the Z direction in the figure, and the direction of the leakage magnetic field from the magnetic recording medium is the Y direction.

In this spin-valve type thin film element, not only the fixed magnetic layer but also the free magnetic layer is divided into two layers of the first free magnetic layer and the second free magnetic layer via the non-magnetic intermediate layer. .

As shown in FIGS. 7 and 8, from the bottom, the underlayer 50,
Antiferromagnetic layer 51, first pinned magnetic layer 52, non-magnetic intermediate layer 53, second pinned magnetic layer 54, non-magnetic conductive layer 55, first
The free magnetic layer 56, the non-magnetic intermediate layer 59, the second free magnetic layer 60, and the protective layer 61 are sequentially stacked.

The base layer 50 and the protective layer 61 are made of, for example, T
a and the like. Further, the antiferromagnetic layer 51 is
It is preferably formed of a PtMn alloy. PtM
The n alloy is an N alloy that has been conventionally used as an antiferromagnetic layer.
Excellent corrosion resistance compared to iMn alloy and FeMn alloy,
Moreover, the blocking temperature is high and the exchange coupling magnetic field is large. Further, in the present invention, instead of the PtMn alloy, X-
Mn (where X is any one or more elements of Pd, Ir, Rh, Ru) alloy, or P
t-Mn-X '(where X'is Pd, Ir, Rh, R
An alloy of any one of u, Au, and Ag or two or more of these elements may be used.

The first pinned magnetic layer 52 and the second pinned magnetic layer 54 are formed of a Co film, a NiFe alloy, a CoFe alloy, a CoNiFe alloy, or the like. The non-magnetic intermediate layer 53 is made of Ru, Rh, Ir, Cr, Re, Cu.
Among them, it is preferable to be formed of one kind or two or more kinds of alloys. Further, the nonmagnetic conductive layer 55 is formed of Cu or the like.

The magnetization of the first pinned magnetic layer 52 and the magnetization of the second pinned magnetic layer 54 are in a ferri state magnetized antiparallel to each other. For example, the magnetization of the first pinned magnetic layer 52 is In the Y direction shown, the magnetization of the second pinned magnetic layer 54 is fixed in the direction opposite to the Y direction shown. To maintain the stability of this ferri state, a large exchange coupling magnetic field is necessary, and in the present invention, various optimizations shown below are performed in order to obtain a larger exchange coupling magnetic field.

In the spin valve thin film element shown in FIGS. 7 and 8, (thickness t _{P1 of} first pinned magnetic layer 52) / (thickness t _{P2 of} second pinned magnetic layer 54) is 0.33. To 0.95, or 1.05 to 4, preferably 0.53 to 0.95 or 1.08.
It is to be within the range of to 1.8.

The film thicknesses of the first pinned magnetic layer 52 and the second pinned magnetic layer 54 are both 10 to 70 angstroms, and | the film thickness t _P1 − of the first pinned magnetic layer 52.
The thickness t _P2 | ≧ 2 angstrom of the second pinned magnetic layer 54 is preferable, and more preferably 10 to 50.
And the film thickness t _{P1 of} the first pinned magnetic layer 52−the film thickness t _P2 | 2 of the second pinned magnetic layer 54 is ≧ 2 angstrom.

As described above, if there is no difference between the magnetic film thickness Ms · t _{p1 of} the first pinned magnetic layer 52 and the magnetic film thickness Ms · t _p2 of the second pinned magnetic layer 54, the magnetization state Is unlikely to be in a ferri state, and even if the difference between the magnetic film thickness Ms · t _{p1 of} the first pinned magnetic layer 52 and the magnetic film thickness Ms · t _p2 of the second pinned magnetic layer 54 becomes too large. However, the exchange coupling magnetic field is lowered, which is not preferable. Therefore, in the present invention, the film thickness t _{p1 of} the first pinned magnetic layer 52 and the second pinned magnetic layer 54 are set.
The magnetic film thickness ratio of the first pinned magnetic layer 52 to the film thickness ratio _{tp2 of} the first pinned magnetic layer 52 (Ms · t _p1 ) / (the second pinned magnetic layer 54 magnetic film thickness Ms · t _p2 ) Is 0.33 to 0.9
It is preferably 5 or within the range of 1.05 to 4. Further, in the present invention, the magnetic film thickness Ms · t _{p1 of} the first pinned magnetic layer 52 and the magnetic film thickness Ms · t _{p2 of} the second pinned magnetic layer 54 are 10 to 70 (angstrom tesla).
And the magnetic film thickness M of the first pinned magnetic layer 52 within the range of
s · t _p1 to the magnetic film thickness Ms · of the second pinned magnetic layer 54.
The absolute value obtained by subtracting t _p2 is 2 (Angstrom Tesla)
The above is preferable.

Further, (magnetic film thickness Ms.t _{p1 of} first pinned magnetic layer 52) / (magnetic film thickness M of second pinned magnetic layer 54)
s · t _p2 ) is 0.53 to 0.95, or 1.05
More preferably, it is within the range of -1.8. Within the above range, the magnetic film thickness M of the first pinned magnetic layer 52 is
s · t _p1 and the magnetic film thickness Ms · t of the second pinned magnetic layer 54.
Both _p2 are in the range of 10 to 50 (angstrom tesla), and moreover, the magnetic film thickness Ms · t _{p1 of} the first pinned magnetic layer 52 to the magnetic film thickness Ms of the second pinned magnetic layer 54.
The absolute value obtained by subtracting t _p2 is preferably 2 (angstrom tesla) or more.

The film thickness of the non-magnetic intermediate layer 53 interposed between the first pinned magnetic layer 52 and the second pinned magnetic layer 54 is 3.6.
It is preferably in the range of ˜9.6 Å. Within this range, an exchange coupling magnetic field of 500 (Oe) or more can be obtained. More preferably 4-9.4.
It is within the range of Angstrom, and within this range, it is possible to obtain an exchange coupling magnetic field of 1000 (Oe) or more.

Further, the thickness of the antiferromagnetic layer 51 is preferably 90 angstroms or more. Within this range, it is possible to obtain an exchange coupling magnetic field of 500 (Oe) or more. More preferably, it is 100 angstroms or more, and within this range, an exchange coupling magnetic field of 1000 (Oe) or more can be obtained.

A first free magnetic layer 56 is formed on the nonmagnetic conductive layer 55 shown in FIGS. Figure 7,
8, the first free magnetic layer 56 is formed of two layers, and the Co film 5 is formed on the side in contact with the nonmagnetic conductive layer 55.
7 are formed. C on the side in contact with the non-magnetic conductive layer 55
The formation of the o film 57 is to firstly increase ΔMR and secondly to prevent diffusion with the nonmagnetic conductive layer 55.

The NiFe alloy film 5 is formed on the Co film 57.
8 is formed. Further, a nonmagnetic intermediate layer 59 is formed on the NiFe alloy film 58. A second free magnetic layer 60 is formed on the non-magnetic intermediate layer 59, and a T layer is formed on the second free magnetic layer 60.
A protective layer 61 formed of a or the like is formed.

The second free magnetic layer 60 is a Co film,
It is formed of a NiFe alloy, a CoFe alloy, a CoNiFe alloy, or the like.

The spin valve film from the base layer 50 to the protective layer 61 shown in FIG. 8 has its side surfaces cut into inclined surfaces, and the spin valve film is formed in a trapezoidal shape. Hard bias layers 62, 62 and conductive layers 63, 63 are formed on both sides of the spin valve film. The hard bias layer 62 is formed of a Co—Pt alloy, a Co—Cr—Pt alloy, or the like, and the conductive layer 63 is formed of Cu or C.
It is formed by r or the like.

A non-magnetic intermediate layer 59 is interposed between the first free magnetic layer 56 and the second free magnetic layer 60 shown in FIGS. 7 and 8, and the first free magnetic layer 56 and the second free magnetic layer 56 are interposed. Exchange coupling magnetic field (RKKY interaction) generated between the magnetic layers 60.
Thus, the magnetization of the first free magnetic layer 56 and the magnetization of the second free magnetic layer 60 are antiparallel to each other (ferri state).

In the spin-valve type thin film element shown in FIG.
For example, the film thickness t _F1 of the first free magnetic layer 56 is formed smaller than the film thickness t _{F2 of} the second free magnetic layer 60. The Ms · t of the first free magnetic layer 56 is
_F1 is set to be smaller than Ms · t _{F2 of} the second free magnetic layer 60, and when a bias magnetic field is applied from the hard bias layer 62 in the X direction in the figure, the second free magnetic layer having a large Ms · t _F2 is obtained. The magnetization of the layer 60 is aligned in the X direction in the figure under the influence of the bias magnetic field, and by the exchange coupling magnetic field (RKKY interaction) with the second free magnetic layer 60, the first Ms · t _{F1 having} a small value. The magnetization of the free magnetic layer 56 is aligned in the direction opposite to the X direction in the drawing.

When an external magnetic field enters from the Y direction in the figure, the magnetizations of the first free magnetic layer 56 and the second free magnetic layer 60 rotate under the influence of the external magnetic field while maintaining the ferri state. To do. The variable magnetization of the first free magnetic layer 56 that contributes to ΔMR and the second pinned magnetic layer 54.
The electric resistance changes due to the relationship with the fixed magnetization (for example, magnetized in the direction opposite to the Y direction in the drawing), and the signal of the external magnetic field is detected.

In the present invention, the film thickness ratio of the film thickness t _F1 of the first free magnetic layer 56 and the film thickness t _F2 of the second free magnetic layer 60 can be optimized to obtain a larger exchange coupling magnetic field. At the same time, it is possible to obtain ΔMR which is almost the same as the conventional one.

In the present invention, (the thickness t _{F1 of} the first free magnetic layer 56 / the thickness t _{F2 of} the second free magnetic layer 60) is
It is preferably within the range of 0.56 to 0.83, or 1.25 to 5. Within this range, it is possible to obtain an exchange coupling magnetic field of at least 500 (Oe) or more. In the present invention, the (first free magnetic layer 56
Film thickness t _F1 / thickness t _{F2 of} the second free magnetic layer 60)
It is more preferably within the range of 0.61 to 0.83, or 1.25 to 2.1. Within this range, it is possible to obtain an exchange coupling magnetic field of at least 1000 (Oe) or more.

(The film thickness t of the first free magnetic layer 56 is_F1
/ Thickness t of the second free magnetic layer 60 _F2) Out of 0.8
Excluding the range of 3 to 1.25 is the first free
Thickness t of magnetic layer 56_F1And the thickness of the second free magnetic layer 60
t_F2Are formed with almost the same value, and the first free magnetic
Ms · t of layer 56_F1And Ms of the second free magnetic layer 60
・ T_F2Are set to almost the same value, the hard bias layer
1st free under the influence of bias magnetic field from 62
Magnetization of either the magnetic layer 56 or the second free magnetic layer 60
Also, because it tries to go toward the bias magnetic field direction,
Magnetization of the first free magnetic layer 56 and second free magnetic layer
The magnetization of the layer 60 does not become an antiparallel state, but a stable magnetization state.
It becomes impossible to keep.

Further, the magnetic film thickness Ms · t _{F1 of} the first free magnetic layer 56 and the magnetic film thickness M of the second free magnetic layer 60.
If there is no difference in s · t _F2 to some extent, the magnetization state is unlikely to be a ferri state, and the magnetic film thickness Ms · t _{F1 of} the first free magnetic layer 56 and the magnetic film of the second free magnetic layer 60. If the difference in the thickness Ms · t _F2 becomes too large, the exchange coupling magnetic field will decrease, which is not preferable. Therefore, in the present invention, the first
Thickness t _F1 and the second free magnetic layer 56 of the free magnetic layer 6
Like the film thickness ratio with the film thickness t _{F2 of} 0, (magnetic film thickness Ms · t _{F1 of} first free magnetic layer 56) / (magnetic film thickness Ms · 2 of second free magnetic layer 60) t _F2 ) is from 0.56
It is preferably within the range of 0.83, or 1.25 to 5. In the present invention, the (first free magnetic layer 5
6 magnetic film thickness Ms · t _F1 ) / (second free magnetic layer 6
It is more preferable that the magnetic film thickness Ms · t _{F2 of} 0 is in the range of 0.61 to 0.83, or 1.25 to 2.1.

In the present invention, the first free magnetic layer 56 is also used.
The nonmagnetic intermediate layer 59 interposed between the second free magnetic layer 60 and the second free magnetic layer 60 is preferably formed of one or more alloys of Ru, Rh, Ir, Cr, Re, and Cu. . Further, the film thickness of the non-magnetic intermediate layer 59 is 5.5.
It is preferably in the range of about 10.0 Å. Within this range, it is possible to obtain an exchange coupling magnetic field of 500 (Oe) or more. The thickness of the non-magnetic intermediate layer 59 is more preferably in the range of 5.9 to 9.4 angstrom. 1 within this range
An exchange coupling magnetic field of 000 (Oe) or more can be obtained.

Within the above numerical range, the film thickness ratio of the first pinned magnetic layer 52 and the second pinned magnetic layer 54, the film thickness of the non-magnetic intermediate layer 53 and the antiferromagnetic layer 51, and the first pinned magnetic layer By adjusting the film thickness ratio between the free magnetic layer 56 and the second free magnetic layer 60 and the film thickness of the non-magnetic intermediate layer 59, it is possible to obtain ΔMR (resistance change rate) similar to the conventional one. is there.

Next, the method of heat treatment will be described. In the spin-valve type thin film element shown in FIGS. 7 and 8, the antiferromagnetic layer 51 is heat-treated with a PtMn alloy or the like, so that the exchange coupling magnetic field (exchange anisotropy) at the interface with the first pinned magnetic layer 52 is exchanged. An antiferromagnetic material that generates a magnetic field is used. Therefore, it is necessary to properly control the direction and magnitude of the magnetic field applied during the heat treatment to adjust the magnetization directions of the first pinned magnetic layer 52 and the second pinned magnetic layer 54.

Assuming that Ms · t _{P1 of} the first pinned magnetic layer 52 is
Is larger than Ms · t _{P2 of} the second pinned magnetic layer 54, 100 to 1 k (Oe) or 5 k (O) in the direction in which the magnetization of the first pinned magnetic layer 52 is desired to be directed.
The magnetic field of e) may be applied. For example, if it is desired to orient the first pinned magnetic layer 52 in the Y direction in the figure, a magnetic field of 100 to 1 k (Oe) is applied in the Y direction in the figure. The magnetization of the first pinned magnetic layer 52 having a large Ms · t _P1 is oriented in the magnetic field direction, that is, the Y direction in the figure, and is exchanged by the exchange coupling magnetic field (exchange anisotropic magnetic field) generated at the interface with the antiferromagnetic layer 51. The magnetization of the first pinned magnetic layer 52 is pinned in the Y direction shown. On the other hand, the magnetization of the second pinned magnetic layer 54 is changed by the exchange coupling magnetic field (RKKY interaction) with the first pinned magnetic layer 52.
It is fixed in the direction opposite to the Y direction in the figure. Alternatively, a magnetic field of 5 k (Oe) or more is applied in the Y direction shown. The exchange coupling magnetic field (RKKY interaction) between the first pinned magnetic layer 52 and the second pinned magnetic layer 54 is 1 k (Oe) to 5 k (Oe).
Therefore, when a magnetic field of 5 k (Oe) or more is applied, both the magnetization of the first pinned magnetic layer 52 and the magnetization of the second pinned magnetic layer 54 are oriented in the Y direction in the figure. At this time, the magnetization of the first pinned magnetic layer 52 is the same as that of the antiferromagnetic layer 5.
Exchange coupling magnetic field generated at the interface with 1 (exchange anisotropic magnetic field)
Is fixed in the Y direction in the figure. On the other hand, 5k (Oe)
When the above magnetic field is removed, the magnetization of the second pinned magnetic layer 54 is fixed in the direction opposite to the Y direction in the figure by the exchange coupling magnetic field (RKKY interaction) with the first pinned magnetic layer 52. To be done.

When Ms · t _P1 of the first pinned magnetic layer 52 is smaller than Ms · t _{P2 of} the second pinned magnetic layer 54, it is desired to direct the magnetization of the first pinned magnetic layer 52. A magnetic field of 100 to 1 k (Oe) or 5 k (Oe) or more may be applied in the direction opposite to the direction, or in the direction in which the magnetization of the first pinned magnetic layer 52 is desired to be directed. For example, the first pinned magnetic layer 5
If 2 is desired to be directed in the Y direction in the drawing, a magnetic field of 100 to 1 k (Oe) is applied in the direction opposite to the Y direction in the drawing. As a result, the magnetization of the second pinned magnetic layer 54 having a large Ms · t _P2 is oriented in the direction of the magnetic field, that is, in the direction opposite to the Y direction in the drawing, and the second pinned magnetic layer 54 and the exchange coupling magnetic field (RKK).
The Y interaction) causes the magnetization of the first pinned magnetic layer 52 to be oriented in the Y direction shown. The first pinned magnetic layer 52
Is fixed in the Y direction in the drawing by the exchange coupling magnetic field (exchange anisotropic magnetic field) generated at the interface with the antiferromagnetic layer 51, and the magnetization of the second pinned magnetic layer 54 is in the direction opposite to the Y direction in the drawing. Fixed to. Alternatively, 5k (O
e) The above magnetic field may be applied. By applying a magnetic field of 5 k (Oe) or more, the magnetizations of the first pinned magnetic layer 52 and the second pinned magnetic layer 54 are both directed in the Y direction in the drawing, and the magnetization of the first pinned magnetic layer 52 is Antiferromagnetic layer 5
It is fixed in the Y direction in the figure by the exchange coupling magnetic field (exchange anisotropic magnetic field) at the interface with 1. When the magnetic field of 5 k (Oe) or more is removed, the magnetization of the second pinned magnetic layer 54, which was oriented in the Y direction in the figure, is changed by the exchange coupling magnetic field (RKKY interaction) with the first pinned magnetic layer 52. It is fixed in the direction opposite to the Y direction in the drawing.

In the present invention, when the X direction and the Y direction shown in the drawing are positive, and the direction opposite to the X direction shown and the direction opposite to the Y direction are negative, the first free magnetic layer 5 is formed.
6 Ms · t _F1 and the second free magnetic layer 60 Ms · t _F2
The sum, the absolute value of a so-called synthetic magnetic moment than the absolute value of the resultant magnetic moment and Ms · t _P1 of the first pinned magnetic layer 52 the sum of Ms · t _P2 of the second pinned magnetic layer 54 Is also preferably larger. That is, │
(Ms · t _F1 + Ms · t _F2 ) / (Ms · t _p1 + Ms · t
_P2 ) │> 1 is preferable.

The absolute value of the combined magnetic moment of the first free magnetic layer 56 and the second free magnetic layer 60 is the absolute value of the combined magnetic moment of the first pinned magnetic layer 52 and the second pinned magnetic layer 54. By increasing the value, the first
The magnetizations of the free magnetic layer 56 and the second free magnetic layer 60 are less likely to be affected by the combined magnetic moment of the first pinned magnetic layer 52 and the second pinned magnetic layer 54.
The magnetizations of the free magnetic layer 56 and the second free magnetic layer 60 are rotated with high sensitivity to an external magnetic field, and the output can be improved.

FIG. 9 is a cross sectional view schematically showing a spin-valve type thin film element according to a fifth embodiment of the present invention, and FIG.
FIG. 10 is a cross-sectional view of the spin-valve thin film element shown in FIG. 9 when viewed from the surface facing a recording medium.

This spin-valve type thin film element is shown in FIGS.
The spin-valve type thin film element shown in FIG.

That is, from the bottom, the underlayer 70, the second free magnetic layer 71, the non-magnetic intermediate layer 72, the first free magnetic layer 73, the non-magnetic conductive layer 76, the second pinned magnetic layer 77, and the non-magnetic intermediate layer. Layer 78, first pinned magnetic layer 79, antiferromagnetic layer 8
0 and the protective layer 81 are laminated in this order.

The base layer 70 and the protective layer 81 are made of, for example, T
a and the like. The antiferromagnetic layer 80 is Pt.
It is preferably formed of a Mn alloy. The PtMn alloy is NiM which has been used as an antiferromagnetic layer from the past.
Compared with n alloys and FeMn alloys, the corrosion resistance is excellent, the blocking temperature is high, and the exchange coupling magnetic field is large. Further, in the present invention, X-Mn is used instead of the PtMn alloy.
(However, X is one or more elements selected from Pd, Ir, Rh, and Ru.) Alloy, or Pt-
Mn-X '(where X'is Pd, Ir, Rh, Ru,
Alloys containing at least one element selected from Au and Ag) may be used.

The first pinned magnetic layer 79 and the second pinned magnetic layer 77 are formed of a Co film, a NiFe alloy, a CoFe alloy, a CoNiFe alloy, or the like. The non-magnetic intermediate layer 78 is made of Ru, Rh, Ir, Cr, Re, Cu.
Among them, it is preferable to be formed of one kind or two or more kinds of alloys. Further, the nonmagnetic conductive layer 76 is formed of Cu or the like.

In the spin-valve type thin film element shown in FIGS. 9 and 10, (film thickness t _{P1 of} first pinned magnetic layer 79) / (film thickness t _{P2 of} second pinned magnetic layer 77) is 0. 33-0.9
5, or preferably in the range of 1.05 to 4, yet the film thickness t _P2 is are both 10-70 Angstroms first thickness t _P1 and the second fixed magnetic layer 77 of the pinned magnetic layer 79 Within the range, and || first pinned magnetic layer 79
Film thickness t _P1 −the film thickness t _{P2 of} the second pinned magnetic layer 77 ≧≧ 2 Å. By properly adjusting within the above range, it is possible to obtain an exchange coupling magnetic field of 500 (Oe) or more.

Further, in the present invention, (first pinned magnetic layer 7
9 film thickness t _P1 ) / (film thickness t _{P2 of} second pinned magnetic layer 77)
Is more preferably in the range of 0.53 to 0.95, or 1.05 to 1.8, and further, the film thickness t _{P1 of} the first pinned magnetic layer 79 and the second pinned magnetic layer 77. Film thickness t
Both _P2 are in the range of 10-50 Angstroms,
And the thickness t _P1 of │ first pinned magnetic layer 79 - and more preferably a second thickness t _P2 │ ≧ 2 angstroms or more fixed magnetic layer 77. With proper adjustment within the above range, it is possible to obtain an exchange coupling magnetic field of 1000 (Oe) or more.

As described above, the first pinned magnetic layer 79
Magnetic film thickness Ms · t_P1And the magnetic properties of the second pinned magnetic layer 77.
Thickness Ms · t_P2If there is no difference in
It is difficult for the first pinned magnetic layer 79 to be magnetized.
Air thickness Ms · t_P1And a magnetic film of the second pinned magnetic layer 77.
Thickness Ms ・ t_P2Even if the difference between
It is not preferable because it leads to a decrease in Therefore, in the present invention,
The thickness t of the fixed magnetic layer 79 of No. 1_p1And the second pinned magnetic layer 77
Film thickness t_p1And the film thickness ratio of
Magnetic film thickness of layer 79 Ms · t_P1) / (Second pinned magnetic layer)
77 magnetic film thickness Ms · t_P2) Is 0.33 to 0.9
5 or preferably in the range of 1.05 to 4
Yes. Further, in the present invention, the magnetic film of the first pinned magnetic layer 79.
Thickness Ms ・ t _P1And the magnetic film thickness M of the second pinned magnetic layer 77.
s ・ t_P2From 10 to 70 (Angstrom Tesla)
Within the range, and the magnetic film thickness Ms of the first pinned magnetic layer 79.
・ T _P1To the magnetic film thickness Ms · t of the second pinned magnetic layer 77.
_P2Is less than 2 (Angstrom Tesla)
The above is preferable.

Further, (magnetic film thickness Ms · t _{P1 of} first pinned magnetic layer 79) / (magnetic film thickness M of second pinned magnetic layer 77)
s · t _P2 ) is 0.53 to 0.95, or 1.05
More preferably, it is within the range of -1.8. Within the above range, the magnetic film thickness M of the first pinned magnetic layer 79 is
s · t _P1 and the magnetic film thickness Ms · t of the second pinned magnetic layer 77.
Both _P2 are in the range of 10 to 50 (angstrom tesla), and moreover, the magnetic film thickness Ms · t _{P1 of} the first pinned magnetic layer 79 to the magnetic film thickness Ms of the second pinned magnetic layer 77.
The absolute value obtained by subtracting t _P2 is preferably 2 (angstrom tesla) or more.

The film thickness of the non-magnetic intermediate layer 78 interposed between the first pinned magnetic layer 79 and the second pinned magnetic layer 77 is:
It is preferably within the range of 2.5 to 6.4, or 6.6 to 10.7 angstrom. Within this range, an exchange coupling magnetic field of 500 (Oe) or more can be obtained. More preferably, it is within the range of 2.8 to 6.2 angstroms or 6.8 to 10.3 angstroms, and within this range, an exchange coupling magnetic field of 1000 (Oe) or more can be obtained. .

Further, the thickness of the antiferromagnetic layer 80 is preferably 90 angstroms or more. Within this range, it is possible to obtain an exchange coupling magnetic field of 500 (Oe) or more. More preferably, it is 100 angstroms or more, and within this range, an exchange coupling magnetic field of 1000 (Oe) or more can be obtained.

In the spin valve thin film element shown in FIG. 10, the free magnetic layer is divided into two layers,
The first free magnetic layer 73 is provided on the side in contact with the non-magnetic conductive layer 76.
Is formed, and the other free magnetic layer serves as the second free magnetic layer 71. As shown in FIG. 10, the first free magnetic layer 73 is formed of two layers, and the layer 75 formed on the side in contact with the nonmagnetic conductive layer 76 is formed of a Co film. The layer 74 formed on the side in contact with the non-magnetic intermediate layer 72 and the second free magnetic layer 71 are made of, for example, Ni.
It is formed of an Fe alloy, a CoFe alloy, a CoNiFe alloy, or the like.

The spin valve film from the base layer 70 to the protective layer 81 shown in FIG. 10 has its side surfaces cut into inclined surfaces, and the spin valve film is formed in a trapezoidal shape. Hard bias layers 82 and 82 and conductive layers 83 and 83 are formed on both sides of the spin valve film. The hard bias layer 82 is formed of a Co—Pt alloy, a Co—Cr—Pt alloy, or the like, and the conductive layer 83 is formed of Cu, Cr, or the like.

A nonmagnetic intermediate layer 72 is interposed between the first free magnetic layer 73 and the second free magnetic layer 71 shown in FIG. 10, and the first free magnetic layer 73 and the second free magnetic layer are provided. Due to the exchange coupling magnetic field (RKKY interaction) generated between 71, the magnetization of the first free magnetic layer 73 and the magnetization of the second free magnetic layer 71 are in an antiparallel state (ferry state). In the spin valve thin film element shown in FIG.
For example, the film thickness T _F1 of the first free magnetic layer 73 is formed to be larger than the film thickness T _{F2 of} the second free magnetic layer 71.
Then, the Ms · t _F1 of the first free magnetic layer 73 is set to be larger than the Ms · t _{F2 of} the second free magnetic layer 71, and the hard bias layer 82 indicates X.
When a bias magnetic field is applied in the direction, the magnetization of the first free magnetic layer 73 having a large Ms · t _F1 is influenced by the bias magnetic field and is aligned in the X direction in the drawing, so that the first free magnetic layer 73 and The magnetization of the second free magnetic layer 71 having a small Ms · t _F2 is aligned in the direction opposite to the X direction in the figure by the exchange coupling magnetic field (RKKY interaction) of. In the present invention, the film thickness t _{F1 of} the first free magnetic layer 73 is formed smaller than the film thickness t _{F2 of} the second free magnetic layer 71, and Ms · t _{F1 of} the first free magnetic layer 73 is formed. May be set smaller than Ms · t _{F2 of} the second free magnetic layer 71.

When an external magnetic field enters from the Y direction shown in the drawing, the magnetizations of the first free magnetic layer 73 and the second free magnetic layer 71 rotate under the influence of the external magnetic field while maintaining the ferrimagnetic state. To do. The magnetization direction of the first free magnetic layer 73 that contributes to ΔMR and the second pinned magnetic layer 71
The electric resistance changes depending on the relationship with the fixed magnetization of the, and the signal of the external magnetic field is detected.

According to the present invention, the film thickness ratio between the film thickness T _F1 of the first free magnetic layer 73 and the film thickness T _F2 of the second free magnetic layer 71 can be optimized to obtain a larger exchange coupling magnetic field. At the same time, it is possible to obtain ΔMR which is almost the same as the conventional one.

In the present invention, (thickness t _{F1 of} first free magnetic layer 73 / thickness t _{F2 of} second free magnetic layer 71) is
It is preferably within the range of 0.56 to 0.83, or 1.25 to 5. Within this range, it is possible to obtain an exchange coupling magnetic field of at least 500 (Oe) or more. In the present invention, the (first free magnetic layer 73
Film thickness t _F1 / thickness t _{F2 of} the second free magnetic layer 71)
It is more preferably within the range of 0.61 to 0.83, or 1.25 to 2.1. Within this range, it is possible to obtain an exchange coupling magnetic field of at least 1000 (Oe) or more.

Further, the magnetic film thickness Ms · t _{F1 of} the first free magnetic layer 73 and the magnetic film thickness M of the second free magnetic layer 71.
If there is no difference in s · t _F2 to some extent, the magnetization state is unlikely to be a ferri state, and the magnetic film thickness Ms · t _{F1 of} the first free magnetic layer 73 and the magnetic film of the second free magnetic layer 71 are small. If the difference in the thickness Ms · t _F2 becomes too large, the exchange coupling magnetic field will decrease, which is not preferable. Therefore, in the present invention, the first
Thickness t _F1 and the second free magnetic layer 73 of the free magnetic layer 7
_Similarly to the film thickness ratio with the film thickness t _{F2 of} 1, the magnetic film thickness Ms · t _{F1 of} the first free magnetic layer 73 / (the magnetic film thickness Ms · of the second free magnetic layer 71). t _F2 ) is from 0.56
It is preferably within the range of 0.83, or 1.25 to 5. Further, in the present invention, (the first free magnetic layer 73
Magnetic film thickness Ms · t _F1 ) / (second free magnetic layer 71
It is more preferable that the magnetic film thickness Ms · t _F2 of is within the range of 0.61 to 0.83, or 1.25 to 2.1.

Further, in the present invention, the first free magnetic layer 73
The nonmagnetic intermediate layer 72 interposed between the second free magnetic layer 71 and the second free magnetic layer 71 is preferably formed of one or more alloys of Ru, Rh, Ir, Cr, Re, and Cu. . Further, the film thickness of the non-magnetic intermediate layer 72 is 5.5.
It is preferably in the range of about 10.0 Å. Within this range, it is possible to obtain an exchange coupling magnetic field of 500 (Oe) or more. Further, the film thickness of the non-magnetic intermediate layer 72 is more preferably in the range of 5.9 to 9.4 angstrom. 1 within this range
An exchange coupling magnetic field of 000 (Oe) or more can be obtained.

The film thickness ratio of the first pinned magnetic layer 79 and the second pinned magnetic layer 77, the non-magnetic intermediate layer 78 and the antiferromagnetic layer 8 are set.
If the film thickness of 0, the film thickness ratio of the first free magnetic layer 73 and the second free magnetic layer 71, and the film thickness of the non-magnetic intermediate layer 72 are properly adjusted within the above range. It is possible to obtain ΔMR (rate of change in resistance) comparable to that of the related art.

Next, the heat treatment method will be described. Temporary
And Ms · t of the first pinned magnetic layer 79. _P1Is the second
Ms · t of pinned magnetic layer 77_P2Greater than, before
In the direction in which the magnetization of the first pinned magnetic layer 79 is desired to be directed, 10
Apply a magnetic field of 0 to 1k (Oe) or 5k (Oe)
Just go. Alternatively, Ms · t of the first pinned magnetic layer 79
_P1Is the Ms · t of the second pinned magnetic layer 77._P2Less than
If desired, the magnetization of the first pinned magnetic layer 79 should be oriented.
100-1k (Oe) in the opposite direction, or the above
5 k (O
e) The above magnetic field may be applied. In the present invention,
The magnetization of the first pinned magnetic layer 79 is pinned in the Y direction in the figure.
The magnetization of the second pinned magnetic layer 77 is in the Y direction in the drawing.
It is fixed in the opposite direction. Alternatively, the first fixed magnet
The magnetization of the flexible layer 79 is fixed in the direction opposite to the Y direction in the drawing,
The magnetization of the second pinned magnetic layer 77 is pinned in the Y direction in the figure.
Has been done.

In the present invention, when the X direction and the Y direction shown in the drawing are positive, and the direction opposite to the X direction shown and the direction opposite to the Y direction are negative, the first free magnetic layer 7 is formed.
3 Ms · t _F1 and the second free magnetic layer 71 Ms · t _F2
The sum, the absolute value of a so-called synthetic magnetic moment than the absolute value of the resultant magnetic moment and Ms · t _P1 of the first pinned magnetic layer 79 the sum of Ms · t _P2 of the second pinned magnetic layer 77 Is also preferably larger. That is, │
(Ms · t _F1 + Ms · t _F2 ) / (Ms · t _p1 + Ms · t
_P2 ) │> 1 is preferable.

The absolute value of the combined magnetic moment of the first free magnetic layer 73 and the second free magnetic layer 71 is calculated as the absolute value of the combined magnetic moment of the first pinned magnetic layer 79 and the second pinned magnetic layer 77. By increasing the value, the first
Of the first free magnetic layer 79 and the second free magnetic layer 77 are less susceptible to the combined magnetic moment of the first pinned magnetic layer 79 and the second pinned magnetic layer 77.
The magnetizations of the free magnetic layer 73 and the second free magnetic layer 71 are rotated with high sensitivity to an external magnetic field, and the output can be improved.

FIG. 11 is a transverse sectional view showing the structure of the spin-valve type thin film element according to the sixth embodiment of the present invention.
FIG. 12 is a cross-sectional view of the spin-valve type thin film element shown in FIG. 11 viewed from the side facing a recording medium.

This spin-valve thin-film element is a dual spin-valve thin-film element in which a nonmagnetic conductive layer, a pinned magnetic layer, and an antiferromagnetic layer are laminated above and below a free magnetic layer as a center. The magnetic layer and the pinned magnetic layer are divided into two layers with a nonmagnetic intermediate layer interposed therebetween.

The lowermost layer shown in FIGS. 11 and 12 is an underlayer 91. On this underlayer 91, an antiferromagnetic layer 92, a first pinned magnetic layer (bottom) 93, Non-magnetic intermediate layer 94 (lower), second pinned magnetic layer (lower) 95, non-magnetic conductive layer 96, second free magnetic layer 97, non-magnetic intermediate layer 1
00, the first free magnetic layer 101, the non-magnetic conductive layer 10
4, a second pinned magnetic layer (upper) 105, a nonmagnetic intermediate layer (upper) 106, a first pinned magnetic layer (upper) 107, an antiferromagnetic layer 108, and a protective layer 109 are formed.

First, the material will be described. Antiferromagnetic layer 9
2, 108 are preferably formed of PtMn alloy. The PtMn alloy has excellent corrosion resistance, a high blocking temperature, and a large exchange coupling magnetic field (exchange anisotropic magnetic field), as compared with NiMn alloys and FeMn alloys that have been conventionally used as antiferromagnetic layers. In the present invention,
Instead of the PtMn alloy, X-Mn (where X is P
An alloy of any one of d, Ir, Rh, and Ru or two or more elements, or Pt—Mn—X ′ (where X ′ is Pd, Ir, Rh, Ru, Au, or Ag). Alloys, which may be one or more elements).

First fixed magnetic layer (bottom) 93, (top) 10
7, and the second pinned magnetic layer (bottom) 95, (top) 105
Is a Co film, a NiFe alloy, a CoFe alloy, or C
It is formed of an oNiFe alloy or the like. The non-magnetic intermediate layers (bottom) 94, (top) formed between the first pinned magnetic layers (bottom) 93, (top) 107 and the second pinned magnetic layers (bottom) 95, (top) 105. 106 and the non-magnetic intermediate layer 100 formed between the first free magnetic layer 101 and the second free magnetic layer 97 are Ru, Rh, Ir, Cr, Re,
It is preferable to be formed of one or more alloys of Cu. Furthermore, the nonmagnetic conductive layers 96 and 104 are formed of Cu or the like.

As shown in FIG. 11, the first free magnetic layer 101 and the second free magnetic layer 97 are formed of two layers. The layer 103 of the first free magnetic layer 101 and the layer 98 of the second free magnetic layer 97 formed on the side in contact with the nonmagnetic conductive layers 96 and 104 are formed of a Co film. The layer 102 of the first free magnetic layer 101 and the layer 99 of the second free magnetic layer 97 formed via the non-magnetic intermediate layer 100 are made of, for example, a NiFe alloy, a CoFe alloy, or a CoNiFe alloy. Has been formed.

Layer 9 in contact with nonmagnetic conductive layers 96 and 104
By forming Co films 8 and 103, ΔMR can be increased, and further diffusion with the nonmagnetic conductive layers 96 and 104 can be prevented.

Next, the appropriate range of the film thickness of each layer will be described. First the first pinned magnetic layer formed on the lower side of the free magnetic layer and the thickness t _P1 (bottom) 93, the thickness ratio between the film thickness t _P2 of the second pinned magnetic layer (lower) 95, and the film thickness ratio between the film thickness t _P2 of the free magnetic layer first pinned magnetic layer formed on the upper side of (above) 107 thickness t _P1 and the second fixed magnetic layer (upper) 105 ( First pinned magnetic layer (bottom) 93, (top) 1
07 film thickness t _P1 ) / (second pinned magnetic layer (bottom) 95,
The film thickness t _P2 of (upper) 105 is preferably in the range of 0.33 to 0.95, or 1.05 to 4, and the first pinned magnetic layer (lower) 93, (upper) ) 107 and the second pinned magnetic layer (bottom) 95, (top) 105
Both are formed within the range of 10 to 70 angstroms,
And | thickness t _{P1 of} the first pinned magnetic layer (bottom) 93, (top) 107-second pinned magnetic layer (bottom) 95, (top) 105
The film thickness t _P2 | ≧ 2 angstrom is preferably formed. Within the above range, it is possible to obtain an exchange coupling magnetic field of 500 (Oe) or more.

In the present invention, (the film thickness t _{P1 of} the first pinned magnetic layer (bottom) 93, (top) 107) / (the film thickness of the second pinned magnetic layer (bottom) 95, (top) 105) t _P2 ) is 0.
It is preferably within the range of 53 to 0.95, or 1.05 to 1.8, and the first pinned magnetic layer (bottom)
93, (top) 107 and the second pinned magnetic layer (bottom) 95,
The film thickness of (upper) 105 is formed within the range of 10 to 50 angstroms, and | the film thickness t _{P1 of} the first fixed magnetic layer (lower) 93, (upper) 107 −second fixed magnetic layer It is preferable that the layers (bottom) 95 and (top) 105 are formed to have a film thickness t _P2 | ≧ 2 Å. Within the above range, it is possible to obtain an exchange coupling magnetic field of 1000 (Oe) or more.

In the present invention, as described above, the antiferromagnetic layers 92 and 108 are made of PtMn alloy or the like, and the exchange coupling magnetic field (exchange different magnetic field) is generated at the interfaces with the first pinned magnetic layers (bottom) 93 and (top) 107. An antiferromagnetic material that requires heat treatment to generate an isotropic magnetic field is used.

However, the antiferromagnetic layer 92 and the first pinned magnetic layer (bottom) 93 formed below the free magnetic layer.
At the interface with and, since the diffusion of the metal element easily occurs and the thermal diffusion layer is easily formed, the magnetic film thickness that functions as the first pinned magnetic layer (lower) 93 is the actual film thickness. It is thinner than t _P1 . Therefore, in order to make the exchange-coupling magnetic field generated in the laminated film above the free magnetic layer and the exchange-coupling magnetic field generated in the lower laminated film almost equal to each other, it is formed below the free magnetic layer (first 1 pinned magnetic layer (bottom) 93 film thickness t _P1 / second pinned magnetic layer (bottom) 9
5 (thickness t _P2 ) is formed above the free magnetic layer (thickness t _{P1 of} first pinned magnetic layer (upper) 107 / thickness of second fixed magnetic layer (upper) 105) It is preferably larger than t _P2.The exchange coupling magnetic field generated from the laminated film above the free magnetic layer is made equal to the exchange coupling magnetic field generated from the laminated film below the free magnetic layer to produce the exchange coupling magnetic field. The process deterioration is small, and the reliability of the magnetic head can be improved.

As described above, the first pinned magnetic layer (bottom)
93, (top) 107 magnetic film thickness Ms.t _P1 and second pinned magnetic layer (bottom) 95, (top) 105 magnetic film thickness Ms.t.
If there is no difference in t _P2 to some extent, the magnetization state is unlikely to be a ferri state, and the first pinned magnetic layers (bottom) 93, (top)
107 magnetic film thickness Ms · t _P1 and the second pinned magnetic layer (lower) 95, even if the difference between the magnetic film thickness Ms · t _P2 (upper) 105 is too large, a decrease in the exchange coupling magnetic field Connection is not preferable. Therefore, in the present invention, the first pinned magnetic layer (lower) 93, (top) 107 thickness t _P1 and the second fixed magnetic layer (lower) 95, the thickness ratio of the thickness t _P2 (upper) 105 In the same manner as in (First pinned magnetic layer (bottom) 93, (top) 107
Magnetic film thickness Ms · t _P1 ) / (second pinned magnetic layer (bottom))
95, (top) 105 has a magnetic film thickness Ms · t _P2 of 0.
It is preferably within the range of 33 to 0.95, or 1.05 to 4. Further, in the present invention, the magnetic film thickness Ms · t _{P1 of} the first pinned magnetic layer (bottom) 93, (top) 107 and the magnetic film thickness of the second pinned magnetic layer (bottom) 95, (top) 105. Ms · t _P2 is in the range of 10 to 70 (angstrom tesla), and the first fixed magnetic layer (bottom) 93,
(Top) 107 magnetic film thickness Ms · t _P1 to second pinned magnetic layer (bottom) 95, (top) 105 magnetic film thickness Ms · t _P2
It is preferable that the absolute value obtained by subtracting 2 is 2 (angstrom tesla) or more.

In addition, (the first pinned magnetic layer (bottom) 93,
(Top) 107 magnetic film thickness Ms · t _P1 ) / (second pinned magnetic layer (bottom) 95, (top) 105 magnetic film thickness Ms · t
_P2 ) is 0.53 to 0.95, or 1.05 to 1.
More preferably, it is within the range of 8. Within the above range, the first pinned magnetic layer (bottom) 93, (top) 107
Magnetic film thickness Ms · t _P1 and second pinned magnetic layer (bottom) 9
5, (upper) 105 has a magnetic film thickness Ms · t _P2 of 10
In the range of 50 (angstrom tesla), the first pinned magnetic layer (bottom) 93, (top) 107 magnetic film thickness Ms · t _P1 to the second pinned magnetic layer (bottom) 95,
(Top) The absolute value obtained by subtracting the magnetic film thickness Ms · t _P2 of 105 is preferably 2 (angstrom tesla) or more.

Further, in the present invention, the non-magnetic intermediate layer interposed between the first pinned magnetic layer (lower) 93 and the second pinned magnetic layer (lower) 95 formed below the free magnetic layer. The film thickness of (bottom) 94 is preferably in the range of 3.6 to 9.6 angstroms. 5 within this range
An exchange coupling magnetic field of 00 (Oe) or more can be obtained.
More preferably, it is in the range of 4 to 9.4 Å, and in this range, it is possible to obtain an exchange coupling magnetic field of 1000 (Oe) or more.

Further, the non-magnetic intermediate layer (upper) 10 interposed between the first pinned magnetic layer (upper) 107 and the second pinned magnetic layer (upper) 105 formed above the free magnetic layer.
The film thickness of 6 is preferably in the range of 2.5 to 6.4 angstroms, or 6.6 to 10.7 angstroms. At least 500 within this range
It is possible to obtain an exchange coupling magnetic field of (Oe) or more.
In addition, 2.8 to 6.2 angstrom, or 6.
It is more preferably in the range of 8 to 10.3 Å, and in this range, an exchange coupling magnetic field of 1000 (Oe) or more can be obtained.

Further, in the present invention, the antiferromagnetic layers 92, 10
It is preferable that the film thickness of No. 8 is 100 angstroms or more. By forming the antiferromagnetic layers 92 and 108 to be 100 angstroms or more, at least 50
An exchange coupling magnetic field of 0 (Oe) or more can be obtained. In the present invention, the thickness of the antiferromagnetic layers 92 and 108 is set to 1
At least 1 if formed with 10 angstroms or more
An exchange coupling magnetic field of 000 (Oe) or more can be obtained.

Further, in the present invention, the first free magnetic layer 10
When the film thickness of the first free magnetic layer 101 is t _F1 and the film thickness of the second free magnetic layer 97 is t _F2 , (the film thickness t of the first free magnetic layer 101 is t
_F1 / the thickness t _{F2 of} the second free magnetic layer 97 is 0.56
It is preferably within the range of 0.83 or 1.25 to 1.25. Within this range, it is possible to obtain an exchange coupling magnetic field of 500 (Oe) or more. In addition, (the thickness of the first free magnetic layer / the thickness of the second free magnetic layer)
Is more preferably in the range of 0.61 to 0.83, or 1.25 to 2.1, and in this range, an exchange coupling magnetic field of 1000 (Oe) or more can be obtained.

[0269] Also, the first free somewhat difference in magnetic film thickness Ms · t _F2 of magnetic film thickness Ms · t _F1 and the second free magnetic layer 97 of the magnetic layer 101 is not present, the magnetization state ferrimagnetic state Even if the difference between the magnetic film thickness Ms · t _{F1 of} the first free magnetic layer 101 and the magnetic film thickness Ms · t _F2 of the second free magnetic layer 97 becomes too large, the exchange coupling will occur. This is not preferable because it leads to a decrease in the magnetic field. Therefore, in the present invention,
Similar to the film thickness ratio between the film thickness t _{F1 of} the first free magnetic layer 101 and the film thickness t _{F2 of} the second free magnetic layer 97, (the magnetic film thickness Ms. t _F1 ) / (second
The free magnetic layer 97 has a magnetic film thickness Ms · t _F2 ) of 0.
It is preferably within the range of 56 to 0.83, or 1.25 to 5. Further, in the present invention, (the magnetic film thickness Ms · t _{F1 of} the first free magnetic layer 101) / (the magnetic film thickness Ms · t _{F2 of} the second free magnetic layer 97) is 0.61 to 0.8.
More preferably, it is within the range of 3 or 1.25 to 2.1.

Further, the nonmagnetic intermediate layer 100 interposed between the first free magnetic layer 101 and the second free magnetic layer 97.
Is preferably formed to have a film thickness within the range of 5.5 to 10.0 Å, and within this range, an exchange coupling magnetic field of 500 (Oe) or more can be obtained. . Further, the film thickness of the non-magnetic intermediate layer 100 is more preferably within the range of 5.9 to 9.4 angstroms, and within this range 1000 (O
e) The above exchange coupling magnetic field can be obtained.

In the present invention, the first pinned magnetic layer (bottom)
93, (top) 107 and the second pinned magnetic layer (bottom) 95,
(Upper) film thickness ratio with 105, first pinned magnetic layer (lower) 9
3, (top) 107 and second pinned magnetic layer (bottom) 95,
(Top) 105, non-magnetic intermediate layer (bottom) 94, (top) 10
6, and the film thickness of the antiferromagnetic layers 92 and 108, the film thickness ratio of the first free magnetic layer 101 and the second free magnetic layer 97, and the film thickness of the nonmagnetic intermediate layer 100 within the above ranges. By appropriately adjusting with, it is possible to obtain the same ΔMR as the conventional one.

By the way, in the dual spin-valve type thin film element shown in FIGS. 11 and 12, the second pinned magnetic layers (bottom) 95, (top) formed above and below the free magnetic layer.
The magnetizations of 105 need to be oriented in opposite directions. This is formed by dividing the free magnetic layer into two layers, the first free magnetic layer 101 and the second free magnetic layer 97, and the magnetization of the first free magnetic layer 101 and the second free magnetic layer. This is because the magnetization of 97 is antiparallel.

For example, as shown in FIGS. 11 and 12, assuming that the magnetization of the first free magnetic layer 101 is magnetized in the direction opposite to the X direction in the drawing, the first free magnetic layer 101.
By the exchange coupling magnetic field (RKKY interaction) with
The free magnetic layer 97 is magnetized in the X direction in the figure. The magnetizations of the first free magnetic layer 101 and the second free magnetic layer 97 are adapted to be reversed under the influence of an external magnetic field while maintaining the ferri state.

In the dual spin-valve type thin film element shown in FIGS. 11 and 12, both the magnetization of the first free magnetic layer 101 and the magnetization of the second free magnetic layer 97 are layers involved in ΔMR. And the first free magnetic layer 10
The electrical resistance changes depending on the relationship between the variable magnetizations of the first and second free magnetic layers 97 and the fixed magnetizations of the second pinned magnetic layers (lower) 95 and (upper) 105. In order to exert the function as a dual spin valve type thin film element capable of expecting a larger ΔMR as compared with the single spin valve type thin film element, the resistance change between the first free magnetic layer 101 and the second pinned magnetic layer (upper) 105. Also, the second pinned magnetic layers (bottom) 95, (top) 10 are arranged so that the resistance changes of the second free magnetic layer 97 and the second pinned magnetic layer (bottom) 95 both show the same variation.
It is necessary to control the magnetization direction of No. 5. That is, the first
Free magnetic layer 101 and second pinned magnetic layer (upper) 105
When the resistance change between the second free magnetic layer 9 and
7 and the second pinned magnetic layer (lower) 95 are also maximized in resistance change, and the resistance change between the first free magnetic layer 101 and the second pinned magnetic layer (upper) 105 is minimized. The resistance change between the second free magnetic layer 97 and the second pinned magnetic layer (lower) 95 should be minimized.

Therefore, in the dual spin-valve type thin film element shown in FIGS. 11 and 12, since the magnetizations of the first free magnetic layer 101 and the second free magnetic layer 97 are antiparallel to each other, the second fixed magnetic layer is formed. It is necessary to magnetize the layer (upper) 105 and the second pinned magnetic layer (lower) 95 in opposite directions.

In the present invention, for the above reason, the second
The magnetization of the pinned magnetic layer (bottom) 95 and the magnetization of the second pinned magnetic layer (top) 105 are fixed in the opposite directions. In order to control such a magnetization direction, It is necessary to properly adjust the Ms · t of each pinned magnetic layer and the direction and magnitude of the magnetic field applied during the heat treatment.

First, regarding Ms · t of each pinned magnetic layer,
Free magnetic layer first pinned magnetic layer formed above the the Ms · t _P1 (top) 107, and larger than the Ms · t _P2 of the second pinned magnetic layer (upper) 105, and, Ms · t _P1 of the first pinned magnetic layer (bottom) 93 formed below the free magnetic layer is set to the second pinned magnetic layer (bottom) 9
5 is smaller than Ms · t _P2 , or Ms · t _P1 of the first pinned magnetic layer (upper) 107 formed above the free magnetic layer is set to the second pinned magnetic layer 105.
The first pinned magnetic layer (bottom), which is smaller than Ms · t _{P2 in} (top) and is formed below the free magnetic layer.
93 Ms · t _P1 to the second pinned magnetic layer (bottom) 95 Ms
It must be larger than s · t _P2 .

In the present invention, the antiferromagnetic layers 92 and 108 are annealed (heat treated) in a magnetic field with a PtMn alloy or the like, so that the first pinned magnetic layers (bottom) 93 and (top) 107 are formed.
Since an antiferromagnetic material that generates an exchange coupling magnetic field at the interface with and is used, the direction and magnitude of the magnetic field applied during heat treatment must be adjusted appropriately. In the present invention, Ms · t _P1 of the first pinned magnetic layer (upper) 107 formed above the free magnetic layer is larger than Ms · t _{P2 of} the second pinned magnetic layer (upper) 105. In addition, Ms · t _P1 of the first pinned magnetic layer (bottom) 93 formed below the free magnetic layer is set to the second pinned magnetic layer (bottom) 9
When it is smaller than Ms · t _{P2 of} 5, the magnetization direction of the first pinned magnetic layer (upper) 107 formed above the free magnetic layer is 100 to 1 k.
A magnetic field of (Oe) is applied.

For example, as shown in FIG. 11, when it is desired to direct the magnetization of the first pinned magnetic layer (upper) 107 in the Y direction shown in the drawing, a magnetic field of 100 to 1 k (Oe) is applied in the Y direction shown in the drawing. . Here, the first pinned magnetic layer (top) 107 having a large Ms · t _P1 and the second pinned magnetic layer (bottom) 95 formed below the free magnetic layer are both in the direction of the applied magnetic field, That is, it faces the Y direction in the figure. On the other hand, the magnetization of the second pinned magnetic layer (upper) 105 having a smaller Ms · t _P2 formed on the upper side of the free magnetic layer is 1st pinned magnetic layer (upper).
By the exchange coupling magnetic field (RKKY interaction) with 07,
It is magnetized antiparallel to the magnetization direction of the first pinned magnetic layer (upper) 107. Similarly, the magnetization of the first pinned magnetic layer (bottom) 93 having a smaller Ms · t _P1 formed below the free magnetic layer is in a ferri state with the magnetization of the second pinned magnetic layer (bottom) 95. As a result, the magnet is magnetized in the direction opposite to the Y direction in the drawing. The first pinned magnetic layer (upper) 10 formed above the free magnetic layer by the exchange coupling magnetic field (exchange anisotropic magnetic field) generated at the interface with the antiferromagnetic layer 108 by the heat treatment.
The magnetization of No. 7 is fixed in the Y direction in the drawing, and the magnetization of the second pinned magnetic layer (upper) 105 is fixed in the direction opposite to the Y direction in the drawing. Similarly, the magnetization of the first pinned magnetic layer (lower) 93 formed below the free magnetic layer is pinned in the direction opposite to the Y direction in the figure by the exchange coupling magnetic field (exchange anisotropic magnetic field). , The magnetization of the second pinned magnetic layer (bottom) 95 is Y in the figure.
Fixed in the direction.

The Ms · t _P1 of the first pinned magnetic layer (upper) 107 formed above the free magnetic layer is smaller than the Ms · t _{P2 of} the second pinned magnetic layer (upper) 105. and, and, the first fixed magnetic layer which is formed below the free magnetic layer Ms · t _P1 (bottom) 93, than Ms · t _P2 of the second pinned magnetic layer (lower) 95 When it is increased, the magnetic field is set to 100 in the direction in which the magnetization of the first pinned magnetic layer (lower) 93 formed below the free magnetic layer is desired to be directed.
Give ~ 1k (Oe).

As described above, the second pinned magnetic layers (bottom) 95 and (top) 105 formed above and below the free magnetic layer.
By magnetizing in the opposite direction, it is possible to obtain the same ΔMR as that of the conventional dual spin valve thin film element.

Further, in the present invention, the magnetization of the first free magnetic layer 101 and the magnetization of the second free magnetic layer 97 in the ferri state can be inverted with higher sensitivity to an external magnetic field. The combined magnetic moment of the magnetic moment of the first free magnetic layer 101 and the magnetic moment of the second free magnetic layer 97 is the first pinned magnetic layer formed below the free magnetic layer ( (Bottom) 93 and second pinned magnetic layer (bottom) 95 combined magnetic moment, and first pinned magnetic layer (top) formed above the free magnetic layer. The magnetic moment of 107 and the magnetic moment of the second fixed magnetic layer (upper) 105 may be larger than the combined magnetic moment. That is, for example, when the magnetic moments in the illustrated X direction and the illustrated Y direction are positive values and the magnetic moments in the opposite direction to the illustrated X direction and the opposite direction to the illustrated Y direction are negative values, the combined magnetic moment | Ms · t _F1 + Ms · t _F2 | is the first pinned magnetic layer (top) 107 and the second pinned magnetic layer (top) 105
Synthetic magnetic moment formed by the magnetic moment of
Greater than Ms · t _P1 + Ms · t _P2 | and the combined magnetic moment | Ms · t _P1 + Ms · t _P2 | of the first pinned magnetic layer (bottom) 93 and the second pinned magnetic layer (bottom) 95 Is preferred.

As described above, in the spin-valve type thin film element shown in FIGS. 7 to 12, not only the fixed magnetic layer but also the free magnetic layer has the first free magnetic layer and the second free magnetic layer via the non-magnetic intermediate layer. By dividing the two free magnetic layers into an antiparallel state (ferri state) by an exchange coupling magnetic field (RKKY interaction) generated between the two free magnetic layers. The magnetizations of the first free magnetic layer and the second free magnetic layer can be inverted with high sensitivity to an external magnetic field.

Further, in the present invention, the film thickness ratio between the first free magnetic layer and the second free magnetic layer, and the non-magnetic intervening between the first free magnetic layer and the second free magnetic layer. The film thickness of the intermediate layer, the film thickness ratio between the first pinned magnetic layer and the second pinned magnetic layer, or the non-magnetic intermediate layer interposed between the first pinned magnetic layer and the second pinned magnetic layer. By forming the film thickness of the layer and the film thickness of the antiferromagnetic layer within an appropriate range,
The exchange coupling magnetic field can be increased, and the magnetization state of the first pinned magnetic layer and the second pinned magnetic layer is fixed magnetization,
The magnetization state of the first free magnetic layer and the second free magnetic layer can be changed to a variable magnetization to maintain a thermally stable ferri state, and moreover, a ΔMR comparable to the conventional one can be obtained. Has become.

In the present invention, the antiparallel state (ferry state) between the magnetization of the first pinned magnetic layer and the magnetization of the second pinned magnetic layer is further thermally adjusted by further adjusting the direction of the sense current. It is also possible to maintain a stable state.

In the spin-valve type thin film element, conductive layers are formed on both sides of a laminated film composed of an antiferromagnetic layer, a fixed magnetic layer, a nonmagnetic conductive layer, and a free magnetic layer, and a sense current flows from this conductive layer. Shed The sense current mainly flows in the non-magnetic conductive layer having a low specific resistance, the interface between the non-magnetic conductive layer and the pinned magnetic layer, and the interface between the non-magnetic conductive layer and the free magnetic layer. In the present invention, the pinned magnetic layer is divided into the first pinned magnetic layer and the second pinned magnetic layer, and the sense current is mainly applied to the interface between the second pinned magnetic layer and the non-magnetic conductive layer. Flowing.

When the sense current flows, a sense current magnetic field is formed according to the right-handed screw law. In the present invention, the sense current magnetic field has the same direction as the direction of the synthetic magnetic moment that can be obtained by adding the magnetic moments of the first pinned magnetic layer and the second pinned magnetic layer. The direction of current flow is adjusted.

In the spin-valve type thin film element shown in FIG.
The second pinned magnetic layer 54 is formed below the nonmagnetic conductive layer 15. In this case, the first pinned magnetic layer 5
Of the second and second pinned magnetic layers 54, the direction of the sense current magnetic field is aligned with the magnetization direction of the pinned magnetic layer having the larger magnetic moment.

As shown in FIG. 1, the magnetic moment of the second pinned magnetic layer 54 is larger than that of the first pinned magnetic layer 52, and the magnetic moment of the second pinned magnetic layer 54 is shown. Direction opposite to Y direction (left direction in the figure)
Suitable for Therefore, the combined magnetic moment obtained by adding the magnetic moment of the first pinned magnetic layer 52 and the magnetic moment of the second pinned magnetic layer 54 is directed in the direction opposite to the Y direction in the drawing (left direction in the drawing).

As described above, the nonmagnetic conductive layer 15 is formed above the second pinned magnetic layer 54 and the first pinned magnetic layer 52. For this reason, the sense current magnetic field formed mainly by the sense current 112 flowing mainly in the nonmagnetic conductive layer 15 is directed to the left in the figure below the nonmagnetic conductive layer 15 so that the sense current magnetic field is directed to the left side in the drawing. The flowing direction of 112 may be controlled. By doing so, the direction of the synthetic magnetic moment of the first pinned magnetic layer 52 and the second pinned magnetic layer 54 and the direction of the sense current magnetic field coincide with each other.

As shown in FIG. 1, the sense current 112 is passed in the X direction shown. According to the right-handed screw law, the sense current magnetic field formed by passing the sense current is formed clockwise with respect to the paper surface. Therefore, the sense current magnetic field in the left direction in the figure (the direction opposite to the Y direction in the figure) is applied to the layer below the nonmagnetic conductive layer 15, and the sense magnetic field reinforces the synthetic magnetic moment. The exchange coupling magnetic field (RKKY interaction) acting between the first pinned magnetic layer 52 and the second pinned magnetic layer 54 is amplified, and the magnetization of the first pinned magnetic layer 52 and the second pinned magnetic layer 52 are amplified. The antiparallel state of the magnetization of the pinned magnetic layer 54 can be more thermally stabilized.

In particular, when a sense current of 1 mA is applied, about 30
It is known that a sense current magnetic field of about (Oe) is generated and the element temperature rises by about 15 ° C. Further, the rotation speed of the recording medium is increased to about 1000 rpm, and the increase in the rotation speed raises the temperature inside the apparatus to about 100 ° C. Therefore, for example, when a sense current of 10 mA is applied, the element temperature of the spin valve thin film element is about 250 ° C.
And the sense current magnetic field is 300 (O
e) It becomes large.

In such an extremely high environmental temperature and when a large sense current flows, the magnetic moment of the first pinned magnetic layer 52 and the second pinned magnetic layer 5 are increased.
When the direction of the synthetic magnetic moment that can be obtained by adding 4 and the direction of the sense current magnetic field are opposite to each other, the magnetization of the first pinned magnetic layer 52 and the second pinned magnetic layer 5
The antiparallel state with the magnetization of 4 is easily broken.

In order to withstand even a high environmental temperature, in addition to adjusting the direction of the sense current magnetic field, an antiferromagnetic material having a high blocking temperature is used for the antiferromagnetic layer 11.
Therefore, in the present invention, a PtMn alloy having a blocking temperature of about 400 ° C. is used.

The composite magnetic moment formed by the magnetic moment of the first pinned magnetic layer 52 and the magnetic moment of the second pinned magnetic layer 54 shown in FIG. 1 is directed to the right (Y direction in the drawing) in the figure. In this case, the sense current may be made to flow in the direction opposite to the X direction in the drawing so that the sense current magnetic field is formed counterclockwise with respect to the paper surface.

Next, the sense current direction of the spin valve thin film element shown in FIG. 3 will be described. In FIG. 3, the second pinned magnetic layer 25 and the first pinned magnetic layer 27 are formed above the nonmagnetic conductive layer 24. As shown in FIG.
The magnetic moment of the pinned magnetic layer 27 is larger than that of the second pinned magnetic layer 25, and the direction of the magnetic moment of the first pinned magnetic layer 27 is the Y direction in the drawing (the right direction in the drawing). ). Therefore, the combined magnetic moment of the magnetic moment of the first pinned magnetic layer 27 and the magnetic moment of the second pinned magnetic layer 25 is directed to the right in the figure.

As shown in FIG. 3, the sense current 113 is passed in the X direction shown. According to the right-handed screw law, the sense current magnetic field formed by flowing the sense current 113 is formed clockwise with respect to the paper surface. Since the second pinned magnetic layer 25 and the first pinned magnetic layer 27 are formed above the nonmagnetic conductive layer 24, the second pinned magnetic layer 25 is formed.
And, the sense current magnetic field in the right direction in the figure (the direction opposite to the Y direction in the figure) enters the first pinned magnetic layer 27, which coincides with the direction of the synthetic magnetic moment, and thus the first pinned magnetic layer is formed. The antiparallel state between the magnetization of the magnetic layer 27 and the magnetization of the second pinned magnetic layer 25 is hard to break.

When the combined magnetic moment is directed to the left in the figure (the direction opposite to the Y direction in the figure), the sense current 113 is made to flow in the direction opposite to the X direction in the figure, and the sense current 113 is made to flow. It is necessary to generate the sense current magnetic field formed counterclockwise with respect to the paper surface so that the direction of the combined magnetic moment of the first pinned magnetic layer 27 and the second pinned magnetic layer 25 matches the direction of the sense current magnetic field. There is.

The spin-valve type thin film element shown in FIG.
(Upper) 43 and second pinned magnetic layers (lower) 34, (upper) 41
Is a dual spin-valve type thin film element formed with.

In this dual spin-valve type thin film element, the first pinned magnetic layers (bottom) 32, (top) 43 are arranged so that the combined magnetic moments formed above and below the free magnetic layer 36 are directed in mutually opposite directions. Direction and magnitude of the magnetic moment of the second fixed magnetic layer (bottom) 34, (top)
It is necessary to control the direction and magnitude of the magnetic moment of 41.

As shown in FIG. 5, the magnetic moment of the second pinned magnetic layer (lower) 34 formed below the free magnetic layer 36 is equal to the magnetic moment of the first pinned magnetic layer (lower) 32. And the magnetic moment of the second pinned magnetic layer (lower) 34 is directed to the right in the drawing (Y direction in the drawing). Therefore, the magnetic moment of the first pinned magnetic layer (bottom) 32 and the second pinned magnetic layer (bottom)
The combined magnetic moment that can be obtained by adding the magnetic moments of 34 is oriented in the right direction in the drawing (Y direction in the drawing). The magnetic moment of the first pinned magnetic layer (upper) 43 formed above the free magnetic layer 36 is larger than the magnetic moment of the second pinned magnetic layer (upper) 41, and the first pinned magnetic layer is also fixed. The magnetic moment of the magnetic layer (upper) 43 is directed to the left in the drawing (opposite to the Y direction in the drawing). Therefore, the combined magnetic moment that can be obtained by adding the magnetic moment of the first pinned magnetic layer (upper) 43 and the magnetic moment of the second pinned magnetic layer (upper) 41 is leftward in the figure (Y direction in the figure). (Opposite direction). As described above, in the present invention, the synthetic magnetic moments formed above and below the free magnetic layer 36 are directed in mutually opposite directions.

In the present invention, as shown in FIG. 5, the sense current 114 is passed in the direction opposite to the X direction shown. As a result, the sense current magnetic field formed by flowing the sense current 114 is formed counterclockwise with respect to the paper surface.

The combined magnetic moment formed below the free magnetic layer 36 is in the right direction in the drawing (Y direction in the drawing).
In addition, since the combined magnetic moment formed above the free magnetic layer 36 is directed in the left direction in the drawing (the direction opposite to the Y direction in the drawing), the directions of the two combined magnetic moments are the same as the direction of the sense current magnetic field. The first pinned magnetic layer (bottom) 32 formed under the free magnetic layer 36 in agreement
And the magnetization of the second pinned magnetic layer (bottom) 34 in an antiparallel state, and the magnetization of the first pinned magnetic layer (top) 43 formed above the free magnetic layer 36 and the second pinned magnetic layer. (Top) 4
It is possible to maintain the antiparallel state of the magnetization of No. 1 in a thermally stable state.

The synthetic magnetic moment formed below the free magnetic layer 36 is directed to the left in the figure,
When the combined magnetic moment formed above the free magnetic layer 36 is directed to the right side in the drawing, the sense current 1
It is necessary to cause 14 to flow in the X direction in the drawing so that the direction of the sense current magnetic field formed by flowing the sense current and the direction of the synthetic magnetic moment are matched.

Further, in FIG. 7 and FIG. 9, the spin valve thin film element formed by dividing the free magnetic layer into two layers of the first free magnetic layer and the second free magnetic layer with the non-magnetic intermediate layer interposed therebetween. In the case where the first pinned magnetic layer 52 and the second pinned magnetic layer 54 are formed below the non-magnetic conductive layer 55 as in the spin valve thin film element shown in FIG. In that case, the control of the sense current direction may be performed similarly to the case of the spin valve thin film element shown in FIG.

Further, in the case where the first pinned magnetic layer 79 and the second pinned magnetic layer 77 are formed above the non-magnetic conductive layer 76 as in the spin valve thin film element shown in FIG. The same control of the sense current direction as in the case of the spin valve thin film element shown in FIG. 3 may be performed.

As described above, according to the present invention, the direction of the sense current magnetic field formed by flowing the sense current, the magnetic moment of the first pinned magnetic layer and the magnetic moment of the second pinned magnetic layer are added. By matching the directions of the synthetic magnetic moments that can be obtained by matching, the exchange coupling magnetic field (RKKY interaction) acting between the first pinned magnetic layer and the second pinned magnetic layer is amplified, It is possible to keep the antiparallel state (ferri state) of the magnetization of the first pinned magnetic layer and the magnetization of the second pinned magnetic layer in a thermally stable state.

Particularly in the present invention, an antiferromagnetic material having a high blocking temperature, such as a PtMn alloy, is used for the antiferromagnetic layer in order to further improve thermal stability. It is possible to make the magnetization of the first pinned magnetic layer and the magnetization of the second pinned magnetic layer in the antiparallel state (ferri state) hard to break even when the magnetization is significantly increased as compared with the above.

When the amount of sense current is increased to increase the reproduction output in order to cope with the higher recording density, the sense current magnetic field also increases accordingly. However, in the present invention, the sense current magnetic field is the first. Since it has the effect of amplifying the exchange coupling magnetic field acting between the pinned magnetic layer and the second pinned magnetic layer, the magnetization state of the first pinned magnetic layer and the second pinned magnetic layer is increased by the increase of the sense current magnetic field. Will be more stable.

The control of the sense current direction can be applied to any antiferromagnetic material used in the antiferromagnetic layer. For example, the antiferromagnetic layer and the pinned magnetic layer (first pinned magnetic layer) can be used. Exchange coupling magnetic field (exchange anisotropic magnetic field) at the interface with
It does not matter whether the heat treatment is necessary or not to generate.

Furthermore, even in the case of a single spin-valve type thin film element in which the pinned magnetic layer is formed of a single layer as in the prior art, the direction of the sense current magnetic field formed by flowing the above-mentioned sense current is By matching the magnetization direction of the pinned magnetic layer with the magnetization direction of the pinned magnetic layer, the magnetization of the pinned magnetic layer can be thermally stabilized.

[0312]

EXAMPLE In the present invention, a spin-valve type thin film element formed by dividing a pinned magnetic layer into two layers of a first pinned magnetic layer and a second pinned magnetic layer via a non-magnetic intermediate layer is used. Then
A film thickness ratio between the first pinned magnetic layer and the second pinned magnetic layer,
The relationship between the exchange coupling magnetic field (Hex) and ΔMR (rate of change in resistance) was measured.

First, the first pinned magnetic layer (the pinned magnetic layer on the side in contact with the antiferromagnetic layer) is set to 20 angstroms or 40 nm.
The film thickness of the second pinned magnetic layer was changed with the film thickness fixed to angstrom, and the relationship between the film thickness of the second pinned magnetic layer and the exchange coupling magnetic field and ΔMR was examined. The film configuration used in the experiment is as follows. Si substrate / alumina / T
a (30) / antiferromagnetic layer; PtMn (150) / first pinned magnetic layer; Co (20 or 40) / nonmagnetic intermediate layer; R
u (7) / second pinned magnetic layer; Co (X) / nonmagnetic conductive layer; Cu (25) / free magnetic layer; Co (10) + Ni
It is Fe (40) / Ta (30). The numerical value in parentheses in each layer indicates the film thickness, and the unit is angstrom.

Further, in the present invention, after forming the above spin-valve type thin film element, heat treatment was performed at 260 ° C. for 4 hours while applying a magnetic field of 200 (Oe). The experimental results are shown in FIGS. 14 and 15.

As shown in FIG. 14, the first pinned magnetic layer
Film thickness t of (P1)_P1Fixed at 20 Å
In this case, the film thickness t of the second pinned magnetic layer (P2)_P220 o
In ngström, the exchange coupling magnetic field (He
x) decreases and the film thickness t _P2By thickening
It can be seen that the exchange coupling magnetic field gradually decreases.
It The film thickness t of the first pinned magnetic layer (P1)_P14
The second pinned magnetic layer when pinned at 0 angstrom
Film thickness t of (P2)_P2Suddenly when you set 40 angstroms
The exchange coupling magnetic field drops sharply, and the film thickness t_P240 o
If it is larger than ngstrom, the exchange coupling magnetism gradually increases.
You can see that the world is going down. Also, the film thickness t_P2To
If you make it smaller than 40 angstrom, it will be about 26
The exchange coupling magnetic field becomes large up to Angstrom,
The film thickness t_P2Smaller than 26 angstroms
It turns out that the exchange coupling magnetic field becomes smaller as
It

[0316] Incidentally When the thickness t _P1 of the first pinned magnetic layer (P1) and the thickness t _P2 of the second pinned magnetic layer (P2) are formed substantially the same thickness, rapidly exchange coupling magnetic field May be because the magnetization of the first pinned magnetic layer (P1) and the magnetization of the second pinned magnetic layer (P2) are not magnetized antiparallel to each other, which is unlikely to be a so-called ferri state. Guessed.

As shown in the above film structure, both the first pinned magnetic layer (P1) and the second pinned magnetic layer (P2) are made of Co.
Since they are formed of a film, they have the same saturation magnetization (Ms). Furthermore, by being formed with almost the same film thickness,
The magnetic moment (Ms · t) of the first pinned magnetic layer (P1)
_P1 ) and the magnetic moment of the second pinned magnetic layer (P2) (M
s · t _P2 ) is set to almost the same value.

Since the PtMn alloy is used for the antiferromagnetic layer in the present invention, an exchange coupling magnetic field is generated at the interface with the first pinned magnetic layer (P1) by performing annealing in a magnetic field after film formation. Then, the first pinned magnetic layer (P1) is to be pinned in a certain direction.

However, when the magnetic moments of the first pinned magnetic layer (P1) and the second pinned magnetic layer (P2) are substantially the same, the first magnetic layer is subjected to heat treatment by applying a magnetic field. Pinned magnetic layer (P1) and second pinned magnetic layer (P2)
And both try to go in the direction of the magnetic field. Originally, an exchange coupling magnetic field (RKKY interaction) is generated between the first pinned magnetic layer (P1) and the second pinned magnetic layer (P2), and the first pinned magnetic layer (P1) The magnetization and the magnetization of the second pinned magnetic layer (P2) tend to be magnetized in an antiparallel state (ferri state), but the magnetizations of the first pinned magnetic layer (P1) and the second pinned magnetic layer (P2) are Since the magnetizations are directed toward each other in the magnetic field direction, it is difficult to magnetize in an antiparallel state, and the magnetization states of the first pinned magnetic layer (P1) and the second pinned magnetic layer (P2) are
It is extremely unstable with respect to external magnetic fields.

Therefore, it is preferable to make some difference between the magnetic moment of the first pinned magnetic layer (P1) and the magnetic moment of the second pinned magnetic layer (P2).
As shown, the first difference in the film thickness t _P2 is too large for fixed magnetic layer thickness t _P1 and the second fixed magnetic layer (P1) (P2), the first pinned magnetic layer (P1) If the difference in magnetic moment between the second pinned magnetic layer (P2) and the second pinned magnetic layer (P2) is too large, the exchange-coupling magnetic field lowers, and the antiparallel state is likely to collapse.

16 and 17 show the second pinned magnetic layer (P
The film thickness t _{P2 of} 2) is fixed at 30 Å,
When the film thickness t _P1 of the pinned magnetic layer (P1) of
The thickness t _{P1 of} the first pinned magnetic layer and the exchange coupling magnetic field (He
3 is a graph showing the relationship between x) and ΔMR. The film structure of the spin valve thin film element used in this experiment is as follows. Si substrate / alumina / Ta (30) / PtM
n (150) / first pinned magnetic layer; Co (X) / nonmagnetic intermediate layer; Ru (7) / second pinned magnetic layer; Co (30)
/ Non-magnetic conductive layer; Cu (25) / Free magnetic layer; Co
(10) + NiFe (40) / Ta (30). The numerical value in parentheses in each layer indicates the film thickness, and the unit is angstrom.

Further, in the present invention, after the above spin-valve type thin film element was formed, heat treatment was carried out at 260 ° C. for 4 hours while applying a magnetic field of 200 (Oe).

As shown in FIG. 16, when the film thickness t _P1 of the first pinned magnetic layer (P1) is 30 Å, that is, the same film thickness t _P2 as the film thickness t _{P2 of} the second pinned magnetic layer (P2). It can be seen that the exchange coupling magnetic field (Hex) drops sharply when formed by. This is because of the reason described above.

Also, the film thickness t of the first pinned magnetic layer (P1)
_It can be seen that the exchange coupling magnetic field is small even when _P1 is about 32 Å. This is because the magnetic film thickness of the first pinned magnetic layer is the actual film thickness t due to the generation of the thermal diffusion layer.
_It becomes smaller than _{P1 and} the film thickness of the second pinned magnetic layer t _P2 (=
This is because it approaches 30 angstroms).

The thermal diffusion layer is formed by diffusing a metal element at the interface between the antiferromagnetic layer and the first pinned magnetic layer. The thermal diffusion layer has the film structure used in this experiment. As shown in (3), it tends to occur when the antiferromagnetic layer and the pinned magnetic layer are formed below the free magnetic layer.

In FIG. 18, a dual spin-valve type thin film element is manufactured.
And the film thicknesses of the first pinned magnetic layers when the two pinned magnetic layers are both fixed to 20 angstroms and the film thickness of each of the two first pinned magnetic layers is changed,
It is a graph which shows the relationship with an exchange coupling magnetic field (Hex).
The film structure of the spin valve thin film element used in this experiment is as follows. Si substrate / alumina / Ta (30)
/ Antiferromagnetic layer; PtMn (150) / First pinned magnetic layer (below P1); Co (X) / Nonmagnetic intermediate layer; Ru (6)
/ Second pinned magnetic layer (below P2); Co (20) / Nonmagnetic conductive layer; Cu (20) / Free magnetic layer; Co (10)
+ NiFe (40) + Co (10) / nonmagnetic conductive layer; C
u (20) / second pinned magnetic layer (on P2); Co (2
0) / nonmagnetic intermediate layer; Ru (8) / first pinned magnetic layer (on P1); Co (X) / antiferromagnetic layer; PtMn (1)
50) / protective layer; Ta (30). The numerical value in parentheses in each layer indicates the film thickness, and the unit is angstrom.

Further, in the present invention, after forming the above spin-valve type thin film element, heat treatment was performed at 260 ° C. for 4 hours while applying a magnetic field of 200 (Oe).

In the experiment, the first pinned magnetic layer (below P1) formed below the free magnetic layer was fixed at 25 angstroms, and the first pinned magnetic layer formed above the free magnetic layer was fixed. The thickness of the pinned magnetic layer (on P1) was changed, and the relationship between the film thickness of the first pinned magnetic layer (on P1) and the exchange coupling magnetic field (Hex) was examined.

The first pinned magnetic layer (above P1) formed above the free magnetic layer is fixed at 25 angstroms to form the first pinned magnetic layer below the free magnetic layer. The film thickness (under P1) was changed and the relationship between the film thickness of the first pinned magnetic layer (under P1) and the exchange coupling magnetic field was examined.

As shown in FIG. 18, the first pinned magnetic layer (below P1) was fixed at 25 angstroms, and the film thickness of the first pinned magnetic layer (above P1) was gradually approached to 20 angstroms. Although the exchange coupling magnetic field increases, when the film thickness of the first pinned magnetic layer (on P1) is about 18 to 22 angstroms, it is almost the same as the film thickness of the second pinned magnetic layer (on P1). Since it becomes the film thickness,
Due to the above-mentioned reason, the exchange coupling magnetic field is sharply reduced. Further, it can be seen that when the film thickness of the first pinned magnetic layer (on P1) is gradually increased from 22 angstroms to 30 angstroms, the exchange coupling magnetic field gradually decreases.

As shown in FIG. 18, the first pinned magnetic layer (on P1) is fixed at 25 angstroms 7, and the film thickness of the first pinned magnetic layer (below P1) is gradually approached to 20 angstroms. However, the exchange coupling magnetic field decreases rapidly when the film thickness of the first pinned magnetic layer (below P1) reaches about 18 to 22 angstroms. The first pinned magnetic layer (P1
It can be seen that when the film thickness in (bottom) is larger than 22 Å, the exchange coupling magnetic field increases until the film thickness reaches about 26 Å, but when the film thickness is 26 Å or more, the exchange coupling magnetic field decreases.

Here, the exchange coupling magnetic field in the first pinned magnetic layer (on P1) and the first pinned magnetic layer when the film thickness of the first pinned magnetic layer (P1) is set to about 22 Å. Comparing with the exchange coupling magnetic field in (P1 lower), the film thickness of the first pinned magnetic layer (P1 upper) is about 22.
It can be seen that the exchange coupling magnetic field can be increased when the thickness is set to about angstrom, compared with the case where the first pinned magnetic layer (below P1) is set to about 22 angstrom.
As described above, this is the first pinned magnetic layer (below P1).
Since a thermal diffusion layer is easily formed at the interface with the antiferromagnetic layer, the magnetic film thickness of the first pinned magnetic layer is substantially reduced, and the second pinned magnetic layer (P2 This is because it will be almost the same as the film thickness in (below).

As described above, according to the experimental results shown in FIGS. 14, 16 and 18, in the present invention, the exchange coupling magnetic field of 500 (Oe) or more can be obtained (the first pinned magnetic layer (P
The film thickness of 1) / (film thickness of the second pinned magnetic layer (P2)) was examined.

First, as shown in FIG. 14, when the first pinned magnetic layer (P1) is pinned to 20 angstroms, 5
To obtain an exchange coupling magnetic field of 00 (Oe) or more, (film thickness of first pinned magnetic layer (P1)) / (second pinned magnetic layer (P1)
It is understood that the film thickness 2) must be 0.33 or more and 0.91 or less, or 1.1 or more. The film thickness of the second pinned magnetic layer (P2) at this time is 10 to 6
Within the range of 0 Å (excluding 18 to 22 Å).

Next, as shown in FIG. 14, when the first pinned magnetic layer (P1) is pinned to 40 angstroms, 5
To obtain an exchange coupling magnetic field of 00 (Oe) or more, (film thickness of first pinned magnetic layer (P1)) / (second pinned magnetic layer (P1)
2) film thickness) is 0.57 or more and 0.95 or less, 1.05
It is understood that the number should be 4 or less. The film thickness of the second pinned magnetic layer (P2) at this time is 10 to 6
It is within the range of 0 Å (excluding 38 to 42 Å).

Next, as shown in FIG. 16, when the second pinned magnetic layer (P2) is pinned to 30 Å,
To obtain an exchange coupling magnetic field of 500 (Oe) or more, (first
(Thickness of pinned magnetic layer (P1)) / (thickness of second pinned magnetic layer (P2)) must be 0.33 or more and 0.93 or less, or 1.06 or more and 2.33 or less. I understand. At this time, the first pinned magnetic layer (P1)
Is in the range of 10 to 70 Å (excluding 28 to 32 Å).

Further, as shown in FIG. 18, in the case of a dual spin-valve type thin film element, (film thickness of first pinned magnetic layer (P1)) / (second pinned magnetic layer (P2)) It can be seen that an exchange coupling magnetic field of 500 (Oe) or more can be obtained by removing the range of 0.9 or more and 1.1 or less in the range of (film thickness).

Here, taking the widest range of film thickness ratios with which exchange coupling of 500 (Oe) or more can be obtained (first
(Thickness of pinned magnetic layer (P1)) / (thickness of second pinned magnetic layer (P2)) is in the range of 0.33 to 0.95, or 1.05 to 4.

However, the exchange coupling magnetic field is not limited to the film thickness ratio, and the first pinned magnetic layer (P1) and the second pinned magnetic layer (P
Since the film thickness of 2) is one of the important factors, further, within the range of the above film thickness ratio, the first pinned magnetic layer (P
The film thickness of 1) and the film thickness of the second pinned magnetic layer (P2) are set to 1
Within the range of 0 to 70 angstrom, and from the film thickness of the first pinned magnetic layer (P1) to the second pinned magnetic layer (P2).
If the absolute value obtained by subtracting the film thickness of 2 is set to 2 angstroms or more, it is possible to obtain an exchange coupling magnetic field of 500 (Oe) or more.

Next, in the present invention, an exchange coupling magnetic field of 1000 (Oe) or more can be obtained (film thickness of the first pinned magnetic layer (P1)) / (film of the second pinned magnetic layer (P2)). Thickness).

First, as shown in FIG. 14, when the first pinned magnetic layer (P1) is set to 20 angstroms (first
(Thickness of pinned magnetic layer (P1)) / (thickness of second pinned magnetic layer (P2)) is 0.53 to 0.91, or 1.
If it is 1 or more, an exchange coupling magnetic field of 1000 (Oe) or more can be obtained. The film thickness of the second pinned magnetic layer (P2) at this time is 10 to 38 angstroms (1
8 to 22 angstroms are excluded).

Further, as shown in FIG. 14, when the first pinned magnetic layer (P1) is set to 40 angstroms (first
(The film thickness of the pinned magnetic layer (P1)) / (the film thickness of the second pinned magnetic layer (P2)) is 0.88 to 0.95, or 1.
Within the range of 05 to 1.8, it is possible to obtain an exchange coupling magnetic field of 1000 (Oe) or more. The film thickness of the second pinned magnetic layer (P2) at this time is in the range of 22 to 45 angstroms (excluding 38 to 42 angstroms).

Further, as shown in FIG. 16, when the second pinned magnetic layer (P2) is pinned to 30 angstroms,
(The thickness of the first pinned magnetic layer (P1)) / (the thickness of the second pinned magnetic layer (P2)) is within the range of 0.56 to 0.93, or 1.06 to 1.6. If so, it is possible to obtain an exchange coupling magnetic field of 1000 (Oe) or more. The film thickness of the first pinned magnetic layer (P1) at this time is 10 to 50 angstroms (excluding 28 to 32 angstroms).
Within the range of.

As shown in FIG. 18, in the case of a dual spin valve thin film element, (film thickness of first pinned magnetic layer (P1)) / (second pinned magnetic layer (P2)) It is possible to obtain an exchange coupling magnetic field of 1000 (Oe) or more by setting the film thickness) in the range of 0.5 to 0.9, or 1.1 to 1.5.

Therefore, in order to obtain an exchange coupling magnetic field of 1000 (Oe) or more, the film thickness of the first pinned magnetic layer (P1)) /
(The film thickness of the second pinned magnetic layer (P2)) is 0.53 to
0.95, or 1.05 to 1.8, and further, the film thickness of the first pinned magnetic layer (P1) and the second pinned magnetic layer (P2) within the range of 10 to 50 angstroms. Moreover, it is preferable that the absolute value obtained by subtracting the film thickness of the second pinned magnetic layer (P2) from the film thickness of the first pinned magnetic layer (P1) is 2 angstroms or more.

As shown in FIGS. 15 and 17, if the film thickness ratio and the film thickness range described above are satisfied, ΔMR does not decrease so much, and ΔMR of about 6% or more can be obtained. The value of this ΔMR is the same as or slightly lower than the ΔMR of the conventional spin valve thin film element (limited to the single spin valve thin film element).

Further, as shown in FIG. 15, when the first pinned magnetic layer (P1) is 40 angstroms, ΔMR is slightly smaller than when the second pinned magnetic layer (P1) is 20 angstroms. You can see.

The first pinned magnetic layer (P1) is a layer that does not actually participate in ΔMR, and ΔMR is the pinned magnetization of the second pinned magnetic layer (P2) and the variable magnetization of the free magnetic layer. It is decided in relation to. However, the sense current is Δ
Since it also flows in the first pinned magnetic layer (P1) not involved in MR, so-called shunt loss (shunt loss) occurs, and this shunt loss increases as the film thickness of the first pinned magnetic layer (P1) increases. Become. For the above reasons, the first
The thicker the fixed magnetic layer (P1) is, the more the ΔMR tends to decrease.

Next, the proper film thickness of the non-magnetic intermediate layer formed between the first pinned magnetic layer (P1) and the second pinned magnetic layer (P2) was measured. In the experiment, a bottom type in which an antiferromagnetic layer was formed below the free magnetic layer,
Two types of top-type spin-valve type thin film elements in which an antiferromagnetic layer was formed above the free magnetic layer were manufactured, and the relationship between the film thickness of the nonmagnetic intermediate layer and the exchange coupling magnetic field was investigated. The film structure of the bottom type spin valve thin film element used in the experiment is as follows from the bottom: Si substrate / alumina / Ta (3
0) / antiferromagnetic layer; PtMn (200) / first pinned magnetic layer; Co (20) / nonmagnetic intermediate layer; Ru (X) / second
Fixed magnetic layer; Co (25) / nonmagnetic conductive layer; Co (1
0) / free magnetic layer; Co (10) + NiFe (40)
/ Ta (30), and the film configuration of the top spin-valve thin film element is as follows: Si substrate / alumina / Ta
(30) / free magnetic layer; NiFe (40) + Co (1
0) / nonmagnetic conductive layer; Cu (25) / second pinned magnetic layer; Co (25) / nonmagnetic intermediate layer; Ru (X) / first pinned magnetic layer; Co (20) / antiferromagnetic Layer; PtMn (2
00) / Ta (30). The numerical value in the parentheses represents the film thickness, and the unit is angstrom.

After forming each spin-valve type thin film element,
While applying a magnetic field of 200 (Oe), heat treatment is performed at 260 ° C. for 4 hours. The experimental results are shown in FIG.

As shown in FIG. 19, the behavior of the exchange coupling magnetic field with respect to the film thickness of the Ru film (nonmagnetic intermediate layer) is greatly different between the top type and the bottom type.

In the present invention, the range in which the exchange coupling magnetic field of 500 (Oe) or more can be obtained is preferable, and therefore, in the top type spin valve thin film element,
Ru capable of obtaining an exchange coupling magnetic field of 0 (Oe) or more
It can be seen that the film thickness is in the range of 2.5 to 6.4 angstroms, or 6.6 to 10.7 angstroms. More preferably, it is within a range where an exchange coupling magnetic field of 1000 (Oe) or more is obtained, and the thickness of the Ru film is 2.8 to 6.2 angstroms, or 6.
Within the range of 8 to 10.3 angstroms, 10
It can be seen that an exchange coupling magnetic field of 00 (Oe) or more can be obtained.

Next, in the bottom type spin valve thin film element, the film thickness of the Ru film capable of obtaining an exchange coupling magnetic field of 500 (Oe) or more is in the range of 3.6 to 9.6 angstroms. I understand. Furthermore, 4.0-
1000 in the 9.4 angstrom range
It is possible to obtain an exchange coupling magnetic field of (Oe) or more.

By the way, the suitable range of the thickness of the non-magnetic intermediate layer is different between the top spin valve thin film element and the bottom spin valve thin film element because the first pinned magnetic layer and The exchange coupling magnetic field (RKKY interaction) acting between the second pinned magnetic layer and the second pinned magnetic layer is very sensitive to the relationship with the lattice constant of the underlying film or the change in the value of the energy band of conduction electrons in the magnetic layer. It is presumed that this is due to the reaction.

Next, in the present invention, four types of spin-valve type thin film elements (single spin-valve type thin-film elements) were manufactured, and the antiferromagnetic layer (PtMn) of each spin-valve type thin-film element was manufactured.
The relationship between the film thickness of the alloy) and the exchange coupling magnetic field was measured.

Examples 1 and 2 are spin valve thin film elements in which the pinned magnetic layer is divided into two layers of the first pinned magnetic layer and the second pinned magnetic layer via the non-magnetic intermediate layer, Comparative Example 1 , 2
Is a conventional spin-valve type thin film element having a fixed magnetic layer formed of a single layer.

First, the spin-valve type thin film element of Example 1 is a top type in which an antiferromagnetic layer is formed above the free magnetic layer, and the film constitution is from the bottom to the Si substrate / alumina / Ta (30). / Free magnetic layer; NiFe (40) + C
o (10) / nonmagnetic conductive layer; Cu (25) / second pinned magnetic layer; Co (25) / nonmagnetic intermediate layer; Ru (4) / first pinned magnetic layer; Co (20) / anti Ferromagnetic layer; PtMn
(X) / Ta (30), and the spin valve thin film element of Example 2 is a bottom type in which an antiferromagnetic layer is formed below the free magnetic layer, and the film structure is Si
Substrate / alumina / Ta (30) / antiferromagnetic layer; PtMn
(X) / first pinned magnetic layer; Co (20) / nonmagnetic intermediate layer; Ru (8) / second pinned magnetic layer; Co (25) / nonmagnetic conductive layer; Cu (25) / free magnetic Layer; Co (1
0) + NiFe (40) / Ta (30).

The spin-valve type thin film element of Comparative Example 1 is of the top type in which the antiferromagnetic layer is formed above the free magnetic layer, and the film constitution is from the bottom to the Si substrate / alumina / Ta (30). / Free magnetic layer; NiFe (40) + C
o (10) / nonmagnetic conductive layer; Cu (25) / fixed magnetic layer; Co (40) / antiferromagnetic layer; PtMn (X) / Ta
(30), and the spin-valve type thin film element of Comparative Example 2 is a bottom type in which the antiferromagnetic layer is formed below the free magnetic layer, and the film constitution is from the bottom to Si substrate / alumina / Ta (30) / antiferromagnetic layer; PtMn (X) / fixed magnetic layer; Co (40) / nonmagnetic conductive layer; Cu (25) /
Free magnetic layer; Co (10) + NiFe (40) / Ta
(30).

In the film constitution of each spin-valve type thin film element, the numerical value in parentheses indicates the film thickness, and the unit is angstrom.

Further, in the present invention, after forming the spin-valve type thin film element, a magnetic field of 200 (Oe) in Examples 1 and 2, and a magnetic field of 2 k (Oe) in Comparative Examples 1 and 2. Is applied for 4 hours at 260 ° C. The experimental results are shown in FIG.

As shown in FIG. 20, it can be understood that the exchange coupling magnetic field can be increased by increasing the film thickness of the PtMn alloy in all four types of spin valve thin film elements.

In the present invention, the range in which the exchange coupling magnetic field of 500 (Oe) or more can be obtained is set to a preferable range. Therefore, in Comparative Examples 1 and 2, the PtMn alloys are both formed to have a film thickness of at least 200 angstroms or more. If it is not, it is understood that the exchange coupling magnetic field of 500 (Oe) or more cannot be obtained.

On the other hand, in Examples 1 and 2, PtMn
500 if the thickness of the alloy is 90 angstroms or more
It is understood that it is possible to obtain an exchange coupling magnetic field of (Oe) or more. Therefore, in the present invention, the preferable thickness range of the PtMn alloy is set within the range of 90 to 200 angstroms.

Furthermore, as shown in FIG.
It can be seen that it is possible to obtain an exchange coupling magnetic field of at least 1000 (Oe) or more by setting the film thickness of the PtMn alloy of 1 to 100 angstroms or more. Therefore, in the present invention, a more preferable PtMn alloy film thickness is 100 to 20.
It is set within the range of 0 angstrom.

Next, in the present invention, two types of dual spin-valve type thin film elements were manufactured, and the relationship between the film thickness of the antiferromagnetic layer (PtMn alloy) in each spin-valve type thin film element and the exchange coupling magnetic field was measured. did.

In the embodiment, the pinned magnetic layer is divided into two layers of the first pinned magnetic layer and the second pinned magnetic layer via the non-magnetic intermediate layer to form the dual spin valve thin film element of the present invention. The comparative example is a conventional dual spin-valve type thin film element in which the pinned magnetic layer is a single layer.

First, the film constitution of the spin-valve type thin film element of the example is as follows from the bottom: Si substrate / alumina / Ta (3
0) / antiferromagnetic layer; PtMn (x) / first pinned magnetic layer; Co (20) / nonmagnetic intermediate layer; Ru (6) / second pinned magnetic layer; Co (25) / nonmagnetic conductive Layer; Cu (2
0) / free magnetic layer; Co (10) + NiFe (40)
+ Co (10) / nonmagnetic conductive layer; Cu (20) / second pinned magnetic layer; Co (20) / nonmagnetic intermediate layer; Ru (8)
/ First pinned magnetic layer; Co (25) / Anti-ferromagnetic layer; Pt
Mn (X) / Ta (30), and the film configuration of the spin valve thin film element of the comparative example is as follows from the bottom: Si substrate / alumina / Ta (30) / antiferromagnetic layer; PtMn (X) /
Fixed magnetic layer; Co (30) / nonmagnetic conductive layer; Cu (2
0) / free magnetic layer; Co (10) + NiFe (40)
+ Co (10) / nonmagnetic conductive layer; Cu (20) / fixed magnetic layer; Co (30) / antiferromagnetic layer; PtMn (X) / T
It is a (30).

The numerical value in parentheses in the film structure of each spin-valve type thin film element indicates the film thickness, and the unit is angstrom.

After forming each spin-valve type thin film element,
A magnetic field of 200 (Oe) was used in the example, and 2 k in the comparative example.
Heat treatment is performed at 260 ° C. for 4 hours while applying a magnetic field of (Oe). The experimental results are shown in FIG.

As shown in FIG. 21, PtMn is used in the comparative example.
It can be seen that an exchange coupling magnetic field of 500 (Oe) or more cannot be obtained unless the film thickness of the alloy is about 200 Å or more.

On the other hand, in the embodiment, if the film thickness of the PtMn alloy is 100 angstroms or more, it is 50.
It can be seen that an exchange coupling magnetic field of 0 (Oe) or more can be obtained. Therefore, in the present invention, the preferable thickness of the antiferromagnetic layer is set within the range of 100 to 200 angstrom. Further, in the example, if the PtMn alloy is formed to have a film thickness of 110 Å or more, an exchange coupling magnetic field of 1000 (Oe) or more can be obtained. 110-200
Set within the Angstrom range.

FIG. 22 shows the film thickness of PtMn alloy and Δ
It is a graph which shows the relationship with MR. As shown in FIG. 22, in the comparative example, when the film thickness of the PtMn alloy is formed to be 200 angstroms or more, it is possible to obtain ΔMR of about 10% or more.
It can be seen that even if the film thickness of the Mn alloy is reduced to about 100 Å, ΔMR that is almost the same as the conventional one can be secured.

By the way, of the laminated films in the spin-valve type thin film element, the thickest is the antiferromagnetic layer. Therefore, according to the present invention, as shown in FIGS. 20 and 21, even if the thickness of the antiferromagnetic layer is reduced, specifically, the film of the antiferromagnetic layer of the conventional spin valve thin film element is used. A large exchange coupling magnetic field can be obtained even if the thickness is less than half the thickness. Therefore, in the present invention, the film thickness of the entire spin valve thin film element can be reduced, and
As shown in, even if the gap layers 121 and 125 formed above and below the spin-valve type thin film element 122 are thick enough to ensure insulation, the gap length G
l can be made small and a narrow gap can be realized.

Next, the spin-valve type thin film element according to the present invention, in which the free magnetic layer is divided into two layers of the first free magnetic layer and the second free magnetic layer via the non-magnetic intermediate layer, is manufactured. The relationship between the film thickness ratio between the first free magnetic layer and the second free magnetic layer and the exchange coupling magnetic field was measured. First, the first free magnetic layer (contacting the non-magnetic conductive layer,
The thickness of the free magnetic layer on the side directly involved in ΔMR is 50
The second free magnetic layer (ΔM
The thickness of the free magnetic layer on the side not directly involved in R) was changed. From the bottom, the film structure is Si substrate / alumina / Ta (3
0) / second free magnetic layer (F2); NiFe (X) /
Non-magnetic intermediate layer; Ru (8) / first free magnetic layer (F
1); NiFe (40) + Co (10) / nonmagnetic conductive layer; Cu (20) / Ru (8) / antiferromagnetic layer; PtMn
(150) / Ta (30), the numerical value in the parentheses in each layer indicates the film thickness, and the unit is angstrom.

After forming the spin-valve type thin film element, 2
While applying a magnetic field of 00 (Oe), heat treatment is performed at 260 ° C. for 4 hours.

As shown in FIG. 23, it can be seen that when the film thickness of the second free magnetic layer (F2) increases to about 40 Å, the exchange coupling magnetic field increases. Further, it can be seen that when the film thickness of the second free magnetic layer (F2) becomes 60 angstroms or more, the exchange coupling magnetic field gradually decreases.

When the film thickness of the second free magnetic layer (F2) was in the range of 40 to 60 Å, the exchange coupling magnetic field became so small that it could not be measured. The reason is that the film thickness (= 50 angstrom) of the first free magnetic layer (F1) and the film thickness of the second free magnetic layer have almost the same value, and therefore the first free magnetic layer (F1) ) And the second free magnetic layer (F2) have almost the same magnetic moment, and the magnetization of the first free magnetic layer (F1) and the magnetization of the second free magnetic layer (F2) with respect to the applied magnetic field. Both try to go in the direction of the applied magnetic field. If the magnetic moment values are different, the first free magnetic layer (F1) and the second free magnetic layer (F1)
Of the exchange coupling magnetic field (RK) between the free magnetic layer (F2) of
KY interaction) occurs, and the first free magnetic layer (F
The magnetization of 1) and the magnetization of the second free magnetic layer (F2) tend to be antiparallel to each other.
Since the magnetization of the free magnetic layer (F1) and the magnetization of the second free magnetic layer (F2) both try to go in the same direction, the first free magnetic layer (F1) and the second free magnetic layer (F1) The magnetization state with F2) becomes unstable, and as described later, the relative angle between the variable magnetization of the second free magnetic layer (F2) and the fixed magnetization of the pinned magnetic layer (first pinned magnetic layer) is It becomes out of control, and ΔMR drops sharply.

In the present invention, the range in which the exchange coupling magnetic field of 500 (Oe) or more can be obtained is set to a preferable range. Therefore, as shown in FIG. 23, (the film of the first free magnetic layer (F1) is If the thickness) / (the thickness of the second free magnetic layer (F2)) is formed within the range of 0.56 to 0.83 or 1.25 to 5, the exchange coupling magnetic field of 500 (Oe) or more. You can get

Further, as described above (first free magnetic layer (F1))
Film thickness / the film thickness of the second free magnetic layer (F2)).
It is more preferable to form it in the range of 61 to 0.83, or 1.25 to 2.1 because an exchange coupling magnetic field of 1000 (Oe) or more can be obtained.

Next, in the present invention, the spin valve thin film element according to the present invention in which the free magnetic layer is divided into two layers of the first free magnetic layer and the second free magnetic layer via the non-magnetic intermediate layer. Was manufactured, and the relationship between the film thickness ratio between the first free magnetic layer and the second free magnetic layer and ΔMR was measured. First, the second free magnetic layer (the free magnetic layer on the side not directly involved in ΔMR) is fixed at 20 Å, and the first free magnetic layer (contacting the nonmagnetic conductive layer, ΔM
The thickness of the free magnetic layer on the side directly involved in R) was changed. From the bottom, the film structure is Si substrate / alumina / Ta (3
0) / second free magnetic layer; NiFe (20) / nonmagnetic intermediate layer; Ru (8) / first free magnetic layer; NiFe
(X) + Co (10) / nonmagnetic conductive layer; Cu (20) /
First pinned magnetic layer; Co (25) / nonmagnetic intermediate layer; Ru
(8) / second pinned magnetic layer; Co (20) / antiferromagnetic layer; PtMn (15) / Ta (30), the numerical value in parentheses in each layer indicates the film thickness, and the unit is angstrom. Is.

In the present invention, after forming the spin-valve type thin film element, a magnetic field of 200 (Oe) is applied and heat treatment is performed at 260 ° C. for 4 hours. Further, as can be seen from the above film structure, in the present invention, the first free magnetic layer is formed of two layers, and the thickness of the NiFe film is changed. The experimental results are shown in FIG. 24, where the horizontal axis in FIG.
It is the total thickness of the first free magnetic layer obtained by adding the thickness of the iFe alloy and the thickness of the Co film (= 10 Å).

As shown in FIG. 24, when the film thickness of the first free magnetic layer (F1) approaches 20 Å,
It can be seen that ΔMR drops sharply because the film thickness is almost the same as the film thickness of the second free magnetic layer (F2). Further, as shown in FIG. 24, when the film thickness of the first free magnetic layer (F1) is about 30 angstroms or more, ΔMR increases, and the conventional spin valve thin film element (single spin valve thin film element) is compared. It is possible to obtain a similar ΔMR.

By the way, 500 derived from FIG.
It is possible to obtain an exchange coupling magnetic field of (Oe) or more (first
24, the film thickness of the first free magnetic layer (F1) / (the film thickness of the second free magnetic layer (F2)) is shown in FIG. By setting the thickness) / (the film thickness of the second free magnetic layer (F2)) within the range of 1.25 to 5, a high ΔMR can be obtained.

Next, in the present invention, the film thickness of the non-magnetic intermediate layer interposed between the first free magnetic layer and the second free magnetic layer is changed to replace the film thickness of the non-magnetic intermediate layer. The relationship with the coupling magnetic field was measured. The film structure of the spin-valve type thin film element (dual spin-valve type thin film element) used in the experiment is as follows from the bottom: Si substrate / alumina / Ta (30) / antiferromagnetic layer; PtMn (150) / Ru (6) / non Magnetic conductive layer; Cu (20) / first free magnetic layer; Co (1
0) + NiFe (50) / nonmagnetic intermediate layer; Ru (X) /
First free magnetic layer; NiFe (30) + Co (10)
/ Non-magnetic conductive layer; Cu (20) / Ru (8) / Anti-ferromagnetic layer; PtMn (150) / Ta (30), the value in parentheses in each layer represents the film thickness, and the unit is angstrom. Is.

In the present invention, after forming the spin-valve type thin film element, 260 is applied while applying a magnetic field of 200 (Oe).
Heat treatment is performed for 4 hours at ℃. The experimental results are shown in Fig. 2.
It shows in 0.

As shown in FIG. 20, in order to obtain an exchange coupling magnetic field of 500 (Oe) or more, the thickness of the Ru film should be 5.5-1.
It is understood that the film may be formed within the range of 0.0 angstrom. Further, it is understood that the Ru film may be formed within the thickness range of 5.9 to 9.4 angstrom in order to obtain the exchange coupling magnetic field of 1000 (Oe) or more.

[0387]

According to the present invention described in detail above, the pinned magnetic layer is divided into two layers of the first pinned magnetic layer and the second pinned magnetic layer with the nonmagnetic intermediate layer interposed therebetween, Due to the exchange coupling magnetic field (RKKY interaction) generated between the first pinned magnetic layer and the second pinned magnetic layer, the magnetization of the first pinned magnetic layer and the magnetization of the second pinned magnetic layer are antiparallel. By setting the state, the magnetization state of the pinned magnetic layer can be kept very stable.

Particularly, in the present invention, the exchange coupling of 500 (Oe) or more is achieved by adjusting the film thickness ratio between the first pinned magnetic layer and the second pinned magnetic layer and the film thickness within an appropriate range. It is possible to obtain a magnetic field, more preferably an exchange coupling magnetic field of 1000 (Oe) or more.

In the present invention, the nonmagnetic intermediate layer interposed between the first pinned magnetic layer and the second pinned magnetic layer is R
u, Rh, Ir, Cr, Re, Cu, etc., and the case where the non-magnetic intermediate layer is formed above the free magnetic layer and the case where the non-magnetic intermediate layer is formed below the free magnetic layer. By adjusting the film thickness of the non-magnetic intermediate layer within an appropriate range, it is possible to obtain an exchange coupling magnetic field of 500 (Oe) or more, more preferably 1000 (Oe) or more. be able to.

Further, in the present invention, the antiferromagnetic layer has a high blocking temperature, and the exchange coupling magnetic field (exchange anisotropic magnetic field) generated at the interface with the pinned magnetic layer (first pinned magnetic layer) is large. Moreover, a PtMn alloy is used as an antiferromagnetic material having excellent corrosion resistance. Or X-Mn
(However, X is any one kind or two or more kinds elements of Pd, Ir, Rh, Ru), Pt—Mn—X ′ (where X ′ is Pd, Ir, Rh, Ru, Au, Ag) Any one of them or two or more of them) may be formed.

When the pinned magnetic layer is divided into the first pinned magnetic layer and the second pinned magnetic layer as in the present invention,
Even if the thickness of the antiferromagnetic layer is about half that of the conventional antiferromagnetic layer, an exchange coupling magnetic field of 500 (Oe) or more can be obtained, and more preferably 1000 (Oe).
The above exchange coupling magnetic field can be obtained.

Further, in the present invention, it is preferable that the free magnetic layer is divided into the first free magnetic layer and the second free magnetic layer via the non-magnetic intermediate layer, similarly to the fixed magnetic layer. . An exchange coupling magnetic field (RKKY interaction) is generated between the first free magnetic layer and the second free magnetic layer, and the magnetization of the first free magnetic layer and the magnetization of the second free magnetic layer are separated from each other. It is magnetized in an antiparallel state and can be inverted with high sensitivity to an external magnetic field.

In the present invention, the film thickness ratio between the first free magnetic layer and the second free magnetic layer is formed within an appropriate range, and the first free magnetic layer and the second free magnetic layer are formed. If a nonmagnetic intermediate layer interposed between the layers is formed of a Ru film or the like and the thickness of the nonmagnetic intermediate layer is formed within an appropriate range, an exchange coupling magnetic field of 500 (Oe) or more can be obtained. It is possible, and more preferably, an exchange coupling magnetic field of 1000 (Oe) or more can be obtained.

Further, according to the present invention, when an antiferromagnetic layer requiring heat treatment at the interface with the first pinned magnetic layer is used, the magnetic moment of the first pinned magnetic layer and the second
Properly adjust the magnitude of the magnetic moment of the fixed magnetic layer of
Further, by appropriately adjusting the direction and magnitude of the magnetic field applied during the heat treatment, the magnetization of the first pinned magnetic layer can be oriented in the desired direction, and the magnetization of the first pinned magnetic layer can be directed. And the magnetization of the second pinned magnetic layer can be appropriately controlled to be in an antiparallel state.

Further, according to the present invention, the direction of the sense current magnetic field formed by flowing the sense current and the first
By making the magnetic moment of the fixed magnetic layer and the magnetic moment of the second fixed magnetic layer coincide with the direction of the synthetic magnetic moment that can be obtained, the first fixed magnetic layer and the second fixed magnetic layer can be obtained. The magnetization state with the magnetic layer can be further thermally stabilized.

The control of the sense current direction can be applied to any antiferromagnetic material used in the antiferromagnetic layer. For example, the antiferromagnetic layer and the pinned magnetic layer (first pinned magnetic layer) can be used. Exchange coupling magnetic field (exchange anisotropic magnetic field) at the interface with
It does not matter whether the heat treatment is necessary or not to generate.

Further, even in the case of a single spin-valve type thin film element in which the pinned magnetic layer is formed of a single layer as in the conventional case, the direction of the sense current magnetic field formed by flowing the above-mentioned sense current is By matching the magnetization direction of the pinned magnetic layer with the magnetization direction of the pinned magnetic layer, the magnetization of the pinned magnetic layer can be thermally stabilized.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a spin valve thin film element according to a first embodiment of the present invention,

FIG. 2 is a cross-sectional view of the spin-valve thin film element shown in FIG. 1 viewed from the side facing a recording medium,

FIG. 3 is a cross-sectional view of a spin valve thin film element according to a second embodiment of the present invention,

4 is a cross-sectional view of the spin-valve thin-film element shown in FIG. 3 viewed from the side facing a recording medium,

FIG. 5 is a cross-sectional view of a spin valve thin film element of a third embodiment of the present invention,

6 is a cross-sectional view of the spin-valve thin-film element shown in FIG. 5 viewed from the side facing a recording medium,

FIG. 7 is a cross-sectional view of a spin valve thin film element according to a fourth embodiment of the present invention,

8 is a cross-sectional view of the spin-valve thin film element shown in FIG. 7 viewed from the side facing a recording medium,

FIG. 9 is a cross-sectional view of a spin-valve type thin film element according to a fifth embodiment of the present invention,

FIG. 10 is a cross-sectional view of the spin-valve thin film element shown in FIG. 9 viewed from the side facing a recording medium,

FIG. 11 is a cross-sectional view of a spin valve thin film element of a sixth embodiment of the present invention,

12 is a cross-sectional view of the spin-valve thin-film element shown in FIG. 11 viewed from the side facing a recording medium,

FIG. 13 is a cross-sectional view of a read head (playback head) as viewed from a surface facing a recording medium;

FIG. 14 shows a relationship between the film thickness of the second pinned magnetic layer (P2) and the exchange coupling magnetic field when the film thickness of the first pinned magnetic layer (P1) is fixed at 20 or 40 Å.
And (thickness of first pinned magnetic layer (P1)) / (thickness of second fixed magnetic layer (P2)), and exchange coupling magnetic field (Hex)
A graph showing the relationship with

FIG. 15 shows the relationship between the film thickness of the second pinned magnetic layer (P2) and ΔMR (%) when the film thickness of the first pinned magnetic layer (P1) is fixed at 20 or 40 Å. Graph showing,

FIG. 16 shows the relationship between the film thickness of the first pinned magnetic layer (P1) and the exchange coupling magnetic field when the second pinned magnetic layer (P2) is pinned at 30 Å, and (first pinned magnetic layer). A graph showing the relationship between the layer (P1) film thickness) / (the second pinned magnetic layer (P2) film thickness) and the exchange coupling magnetic field (Hex),

FIG. 17 is a graph showing the relationship between the film thickness of the first pinned magnetic layer (P1) and ΔMR (%) when the second pinned magnetic layer (P2) is pinned at 30 Å.

FIG. 18 shows a dual spin valve thin film element
The relationship between the film thickness of the first pinned magnetic layer (top) and the film thickness of the first pinned magnetic layer (bottom), and the exchange coupling magnetic field (Hex), and the film of the first pinned magnetic layer (on P1) Thickness) / (thickness of second pinned magnetic layer (on P2)) and (thickness of first pinned magnetic layer (below P1)) / (second pinned magnetic layer (P2)
A graph showing the relationship between (under) film thickness) and the exchange coupling magnetic field (Hex),

FIG. 19 is a graph showing the relationship between the film thickness of Ru (nonmagnetic intermediate layer) interposed between the first pinned magnetic layer and the second pinned magnetic layer and the exchange coupling magnetic field (Hex);

FIG. 20 uses four kinds of spin-valve type thin film elements,
A graph showing the relationship between the film thickness of PtMn (antiferromagnetic layer) of each spin valve thin film element and the exchange coupling magnetic field (Hex),

FIG. 21: PtMn of each dual spin valve thin film element using two types of dual spin valve thin film elements
A graph showing the relationship between the film thickness of the (antiferromagnetic layer) and the exchange coupling magnetic field (Hex),

FIG. 22 shows PtMn of each dual spin valve thin film element using two types of dual spin valve thin film elements.
A graph showing the relationship between the film thickness of the (antiferromagnetic layer) and ΔMR (%),

FIG. 23 shows the relationship between the film thickness of the second free magnetic layer (F2) and the exchange coupling magnetic field (Hex) when the film thickness of the first free magnetic layer (F1) is fixed at 50 Å, and 1) thickness of free magnetic layer (F1) / (thickness of second free magnetic layer (F2)) and exchange coupling magnetic field (Hex)
A graph showing the relationship with

FIG. 24 is a graph showing the relationship between the film thickness of the first free magnetic layer (F1) and ΔMR (%) when the film thickness of the second free magnetic layer (F2) is fixed at 20 Å, and (first A graph showing the relationship between free magnetic layer (F1) film thickness / (second free magnetic layer (F2) film thickness) and ΔMR (%),

FIG. 25 shows the relationship between the film thickness of Ru (nonmagnetic intermediate layer) interposed between the first free magnetic layer (F1) and the second free magnetic layer (F2) and the exchange coupling magnetic field (Hex). Graph showing,

FIG. 26 is a spin valve thin film element according to the present invention, and a hysteresis loop in a conventional spin valve thin film element;

FIG. 27 shows Ni when the antiferromagnetic layer is formed of PtMn.
A graph showing the relationship between the ambient temperature (° C.) and the exchange coupling magnetic field (Hex) in each spin-valve type thin film element when formed of O and when formed of FeMn,

FIG. 28 is a cross-sectional view of a conventional spin-valve thin film element as viewed from the surface facing a recording medium,

[Description of Reference Signs] 10, 30, 50, 70, 91 Underlayer 11, 28, 31, 44, 51, 80, 92, 108
Antiferromagnetic layer 12, 27, 52, 79 First pinned magnetic layer 13, 26, 33, 42, 53, 59, 72, 78, 9
4, 100, 106 Non-magnetic intermediate layer 14, 25, 54, 77 Second pinned magnetic layer 15, 24, 35, 40, 55, 76, 96, 104
Non-magnetic conductive layers 16, 21, 36 Free magnetic layers 19, 29, 45, 61, 81, 109 Protective layers 32, 93 First pinned magnetic layer (bottom) 34, 95 Second pinned magnetic layer (bottom) 41 , 105 second pinned magnetic layer (upper) 43, 107 first pinned magnetic layer (upper) 56, 73, 101 first free magnetic layer 60, 71, 97 second free magnetic layer 62, 82, 130 Hard bias layers 63, 83, 131 conductive layers 112, 113, 114 sense current

Continued front page       (56) References JP-A-9-16920 (JP, A)                 Japanese Patent Laid-Open No. 7-169026 (JP, A)                 JP 10-105928 (JP, A)                 JP-A-6-223336 (JP, A)                 US Patent 5408377 (US, A)

Claims (7)

(57) [Claims] 1. An antiferromagnetic layer, a pinned magnetic layer which is formed in contact with the antiferromagnetic layer and whose magnetization direction is pinned by an exchange coupling magnetic field with the antiferromagnetic layer, and a non-fixed magnetic layer. In a single spin-valve thin film element having a free magnetic layer formed via a magnetic conductive layer and having a magnetization aligned in a direction intersecting with the magnetization direction of the pinned magnetic layer, the pinned magnetic layer is an antiferromagnetic layer. contact a first fixed magnetic layer, is formed of two layers of the first pinned magnetic layer and the nonmagnetic intermediate layer through the second pinned magnetic layer being superposed, the second
Magnetic momentum of the first pinned magnetic layer and the second pinned magnetic layer
The magnetic moment (saturation magnetization Ms / thickness t) of the first pinned magnetic layer is different from the magnetic moment of the second pinned magnetic layer so that the magnetic fields of the first pinned magnetic layer are antiparallel to each other. The layer is formed of two layers of a first free magnetic layer and a second free magnetic layer with a nonmagnetic intermediate layer interposed therebetween, and the magnetic moment of the first free magnetic layer and the magnetic moment of the second free magnetic layer. And the absolute value of the combined magnetic moment of the first fixed magnetic layer and the second
Is larger than the absolute value of the combined magnetic moment with the magnetic moment of the pinned magnetic layer of 1. 2. A nonmagnetic conductive layer stacked above and below the free magnetic layer, an upper pinned magnetic layer formed on one of the nonmagnetic conductive layers, and a nonmagnetic conductive layer formed on the other nonmagnetic conductive layer. A lower pinned magnetic layer, and an antiferromagnetic layer formed on the upper pinned magnetic layer and below the lower pinned magnetic layer, the upper and lower pinned magnetic layers, and a free magnetic layer. in the dual spin-valve type thin film element bets, which are magnetized in a direction intersecting, each fixed magnetic layer has a first fixed magnetic <br/> layer in contact with the antiferromagnetic layer, the first pinned magnetic is formed of two layers of the second pinned magnetic layer which is superposed over the layer and a non-magnetic intermediate layer, the
Magnetic moment of the first pinned magnetic layer and the second pinned magnetic layer
As the direction of the cement is antiparallel, the magnetic moment of the first pinned magnetic layer (saturation magnetization Ms · thickness t) is, is different from the magnetic moment of the second pinned magnetic layer, the free magnetic The layer is formed of two layers of a first free magnetic layer and a second free magnetic layer with a non-magnetic intermediate layer interposed between the magnetic moment of the first free magnetic layer and the magnetic moment of the second free magnetic layer. the absolute value of the sum combined resultant magnetic moment is greater than the first absolute value of the magnetic moment and the synthesized magnetic moment obtained by adding the magnetic moment of the second pinned magnetic layer of the fixed magnetic layer in the upper fixed magnetic layer, and , scan, wherein greater than the absolute value of the first magnetic moment of the pinned magnetic layer and the resultant magnetic moment obtained by adding the magnetic moment of the second pinned magnetic layer in the lower fixed magnetic layer Nbarubu type thin film element. 3. The above (magnetic thickness of first free magnetic layer / magnetic thickness of second free magnetic layer) is 0.56 to
The spin valve thin film element according to claim 1 or 2, which has a thickness within the range of 0.83 or 1.25 to 5. 4. The (magnetic thickness of first free magnetic layer / magnetic thickness of second free magnetic layer) is 0.61 to
The spin valve thin film element according to claim 3, wherein the spin valve thin film element has a thickness within the range of 0.83 or 1.25 to 2.1. 5. The thickness of the non-magnetic intermediate layer interposed between the first free magnetic layer and the second free magnetic layer is 5.5 to 1
The spin valve thin film element according to any one of claims 1 to 4, wherein the spin valve thin film element has a thickness within the range of 0.0 angstrom. 6. The thickness of the non-magnetic intermediate layer is 5.9 to
The spin valve thin film element according to claim 5, wherein the spin valve thin film element has a thickness in the range of 9.4 Å. 7. A thin-film magnetic head, wherein shield layers are formed above and below the spin-valve thin-film element according to any one of claims 1 to 6 with a gap layer interposed therebetween.