JPH11339226A - Magnetoresistance effect element and magnetic head using the same, magnetic head assembly and magnetic recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the change of the anisotropic magnetic field of a free layer and the reduction of the rate of change in MR based on it, when magnetization directions of upper and lower magnetic layers between which a nonmagnetic layer is interposed are made to be in an orthogonal relation in a spin valve type magnetoresistance effect element. SOLUTION: This magnetoresistance effect element is provided with a magnetoresistance effect film 14, having a first magnetic layer (free layer) 15 whose magnetization direction is changed by an external magnetic field, a nonmagnetic layer 16 and a second magnetic layer (spin layer) 17 whose magnetization is fixed and electrodes which supply a sense current to the magnetoresistance effect film 14. The free layer 15 has relaxing components of two kinds or more, having different mitigation times of anisotropic magnetic field and the first relaxing component (Hk1 ) whose relaxation time is the fastest among the two or more kinds of relaxation components relaxes the anisotropic magnetic field of the layer. The ratio of the first relaxing component is, for example, 60% or more or 40% or less with respect to the total of mitigation components of the anisotropic magnetic field.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetoresistive element having a magnetoresistive film having a magnetic layer / non-magnetic layer / magnetic layer structure, and a magnetic head, a magnetic head assembly and a magnetic recording apparatus using the same.

[0002]

2. Description of the Related Art Generally, in order to read information recorded on a magnetic recording medium, a reproducing magnetic head having a coil is moved relative to the recording medium, and the coil is moved by electromagnetic induction generated at that time. To detect the voltage induced in the magnetic field (induction type head) or the phenomenon that the electric resistance of a certain ferromagnetic material changes according to the strength of the external magnetic field (the magnetoresistance effect (M
R)) (MR head). In recent years, in order to reduce the size and capacity of magnetic recording media,
As the magnetic recording density has been increased, the relative speed between the reproducing head and the magnetic recording medium at the time of reading information has been reduced. For this reason, MR heads capable of taking out a large output even when the relative speed is reduced are being put to practical use.

Conventionally, a portion (MR element) where the resistance changes by sensing the external magnetic field of the MR head is provided by Ni-Fe.
Alloys (so-called permalloy alloys) have been used.
However, although the permalloy alloy has good soft magnetic properties, its magnetoresistance change (MR change) is up to 3%.
Therefore, it is desired to develop a material having higher sensitivity and a large MR change rate for an MR element for a magnetic recording medium recorded at high density. In response to such a request,
Giant MR ratio in an artificial lattice film in which ferromagnetic metal films and non-magnetic metal films such as Fe / Cr and Co / Cu are alternately laminated and adjacent ferromagnetic films are antiferromagnetically coupled. Has been obtained. However, these artificial lattice films are not suitable for MR elements due to their large saturation magnetic field.

On the other hand, a large MR ratio is obtained even when the ferromagnetic film does not have antiferromagnetic coupling in a laminated film having a sandwich film structure of a ferromagnetic film / nonmagnetic film / ferromagnetic film. That is, an exchange bias is applied to one of the two ferromagnetic films sandwiching the non-magnetic film to fix the magnetization (pin layer).
It has a structure in which the magnetization of the other ferromagnetic film is reversed by an external magnetic field (free layer). As described above, by changing the relative angle between the magnetization directions of the two ferromagnetic films disposed with the non-magnetic film interposed therebetween, a large MR change rate can be obtained. Such a magnetoresistive film is called a spin valve film (Phys. Rev. B, Vol. 45, 806 (1992), J. Appl. Phys.
Vol. 69, 4774 (1991)).

Although the MR ratio of the spin valve film is smaller than that of the artificial lattice film, the magnetization can be saturated with a low magnetic field, and thus the spin valve film is suitable for the MR element. For these reasons, research and development of MR heads using spin valve films are being actively pursued for practical use.

Meanwhile, in a spin valve film having a sandwich film structure, the total thickness of the portion where the magnetoresistance effect occurs is small, and the MR change rate greatly depends on the thickness of the ferromagnetic film. For this reason, when a magnetoresistive element is formed using a spin valve film, it is important to select a material for the magnetic layer and set the film thickness.

Further, in a spin valve film, magnetization saturation is realized at a low magnetic field generally by making the magnetization directions of two ferromagnetic films sandwiching a nonmagnetic film mutually orthogonal. In this case, a stable exchange bias is applied to one ferromagnetic film (pin layer) by an antiferromagnetic film or a hard magnetic film to fix the magnetization, and the other ferromagnetic film (free layer) By heat treatment or the like, the orientation is given in a direction perpendicular to the magnetization direction of the pinned layer.

However, the fact that the magnetization directions of the two ferromagnetic films sandwiching the non-magnetic film are perpendicular to each other is not stable in terms of magnetic energy, and therefore the free layer and the pin are not affected by heat applied during head operation. There is a problem that the magnetization directions of the layers are easily changed to either the same direction or antiferromagnetic coupling. As described above, when the magnetization directions of the free layer and the pinned layer change, the MR change rate decreases and the reproduction output as a magnetic head decreases.

[0009]

As described above, in the spin valve film, magnetization saturation in a low magnetic field is realized by setting the magnetization directions of the free layer and the pinned layer to be orthogonal to each other. Since the magnetization state is not stable in terms of magnetic energy, there is a problem that the magnetization directions of the free layer and the pinned layer tend to change to the same direction or to antiferromagnetic coupling.

Since the change in the magnetization direction between the free layer and the pinned layer in the spin valve film causes a reduction in the MR ratio, it is necessary to stably maintain the orthogonal magnetization relationship between the free layer and the pinned layer for a long period of time. It is required to improve the MR change rate of the spin valve film and the reliability of the reproduction output of the magnetic head (MR head) using the same.

SUMMARY OF THE INVENTION The present invention has been made to address such a problem, and in a spin valve film or the like in which the magnetization directions of two magnetic layers are perpendicular to each other, a large MR change rate is stably maintained for a long period of time. A magnetic head, a magnetic head assembly, and a magnetic head having improved characteristics and reliability thereof by using such a magnetoresistive effect element. It is intended to provide a recording device.

[0012]

According to a first aspect of the present invention, there is provided a magnetoresistive element having a first magnetic layer whose magnetization direction is changed by an external magnetic field, and a first magnetic layer which is not in contact with the first magnetic layer. A magnetoresistive effect element comprising: a magnetoresistive effect film having a second magnetic layer laminated and magnetically fixed with a magnetic layer interposed therebetween, and an electrode for supplying a sense current to the magnetoresistive effect film; The first magnetic layer has two or more types of relaxation components having different relaxation times of the anisotropic magnetic field, and among the two or more types of relaxation components, the first relaxation component having the earliest relaxation time relaxes. It is characterized by having.

In the magnetoresistance effect element according to the present invention, the first
The ratio of the first relaxing component to the total relaxing component of the anisotropic magnetic field is 60% or more as described in claim 2, or as described in claim 3, The ratio of the first relaxing component to the total relaxing component of the anisotropic magnetic field is preferably 40% or less.

Further, in the magnetoresistive element according to the present invention, when the magnetization directions of the first magnetic layer and the second magnetic layer are substantially orthogonal to each other, the first anisotropic magnetic field of the first magnetic layer can be reduced. When the relaxation component of 1 is 60% or more, an anisotropic magnetic field is applied to the first magnetic layer in substantially the same direction as the magnetization direction of the second magnetic layer, as described in claim 4. The magnetization direction of the first magnetic layer is substantially perpendicular to the magnetization direction of the second magnetic layer by relaxing the first relaxation component having a ratio of 60% or more. For example, 2
After imparting anisotropy to the magnetization direction of the second magnetic layer at a temperature of 50 ° C. or more, the second magnetic layer is applied to the first magnetic layer at a temperature lower than that temperature.
Anisotropy is provided in a direction substantially perpendicular to the magnetization direction of the magnetic layer.

[0015] When the first relaxing component of the anisotropic magnetic field of the first magnetic layer is 40% or less, the second magnetic layer has a smaller thickness than the first magnetic layer. By applying an anisotropic magnetic field in a direction substantially perpendicular to the magnetization direction and relaxing the first relaxation component having a ratio of 40% or more, the magnetization direction of the first magnetic layer is changed to the magnetization direction of the second magnetic layer. It is characterized by being substantially orthogonal to. For example, after performing a heat treatment for imparting anisotropy to the first magnetic layer, anisotropy is imparted to the second magnetic layer in a direction substantially orthogonal to the magnetization direction of the first magnetic layer. In the magnetoresistance effect element of the present invention, the magnetization fixing temperature of the second magnetic layer can be, for example, 300 ° C. or higher.

In the magnetic head according to the present invention, the magnetic head as a reproducing head is formed with a lower magnetic shield layer and a lower reproducing magnetic gap formed on the lower magnetic shield layer. The magnetoresistive element of the present invention described above, and an upper magnetic shield layer formed on the magnetoresistive element with an upper reproducing magnetic gap interposed therebetween.

According to another aspect of the present invention, a recording / reproducing separation type magnetic head is formed with a lower magnetic shield layer and a lower reproducing magnetic gap formed on the lower magnetic shield layer. A read head having the above-described magnetoresistive element of the present invention, an upper magnetic shield layer formed on the magnetoresistive effect element via an upper read magnetic gap, and a read head shared with the upper magnetic shield layer. The recording head includes a side magnetic pole, a recording magnetic gap formed on the lower magnetic pole, and an upper magnetic pole provided on the recording magnetic gap.

According to a ninth aspect of the present invention, there is provided a magnetic head assembly comprising: a head slider having the recording / reproducing separation type magnetic head according to the present invention; and an arm having a suspension on which the head slider is mounted. It is characterized by having. Further, according to the magnetic recording device of the present invention, as described in claim 10, a magnetic recording medium,
A head slider provided with the above-mentioned recording / reproducing type magnetic head of the present invention, which writes a signal to the magnetic recording medium by a magnetic field and reads a signal by a magnetic field generated from the magnetic recording medium, is provided.

Here, the anisotropic magnetic field H _{k of the} entire magnetic layer is:
It is defined as an anisotropic magnetic field obtained under the following conditions. For example, a magnetic film (for example, Ni ₈₀ Fe ₂₀ (at%) having a film thickness of 10 nm) is formed on a substrate such as thermally oxidized silicon by a normal sputtering method.
After forming a single-layer film of an alloy or a CoFe alloy, or a laminated film of these, a heat treatment is applied to the magnetic film in a state where a magnetic field in a certain direction is applied to impart sufficient anisotropy to the magnetic film. It should be noted that imparting sufficient anisotropy refers to a state in which the magnitude of the anisotropic magnetic field is hardly changed by heat treatment in a magnetic field. In each film configuration such as a single-layer film and a laminated film, an anisotropic magnetic field of a film to which a sufficiently large anisotropy is given by a heat treatment in a magnetic field or the like is _defined as an end point Hk.

As described above, the film provided with magnetic anisotropy in one direction of the film surface is heated at a certain temperature in a state where a magnetic field is applied in a direction perpendicular to the magnetization direction provided with the magnetic anisotropy. , The magnitude of the initially applied anisotropic magnetic field gradually changes. If the holding is performed for a very long time, the direction perpendicular to the direction of the initially applied anisotropic magnetic field (the direction in which the magnetic field is applied) eventually becomes the direction of the anisotropic magnetic field.
Call this behavior and mitigation of anisotropy field, the anisotropic magnetic field relaxation in a direction perpendicular to the initial anisotropy field H _k and -H _k. At this time, the magnitude of the anisotropic magnetic field applied initially (H _k) and the orthogonal direction to the relaxed anisotropy field (-H _k) is the same, H _k = | a relationship | -H _k is there.

As described above, when a magnetic field is applied to a film having an anisotropic magnetic field in a direction orthogonal to a certain temperature, the magnitude and the direction of the anisotropic magnetic field gradually change (relax) over time. However, at this time, there is a component (relative component of the anisotropic magnetic field) having a different speed and magnitude of the relaxation of the anisotropic magnetic field. Of the two or more types of relaxation components, the component having the fastest relaxation time is the first relaxation component (the first anisotropic magnetic field H
and _k1), the relaxation time of the time and τ _1. Also, H
The relaxation component of the anisotropic magnetic field that relaxes later than _k1 is, for example, a second relaxation component (second anisotropic magnetic field H _k2 ), and the relaxation time at that time is τ ₂ .

When the magnetic layer has two or more kinds of anisotropic magnetic field relaxation components having different relaxation speeds and magnitudes, the respective relaxation times (for example, τ ₁ and τ ₂ ) change depending on the temperature, and the relaxation time increases as the temperature rises. Become. In addition, the ratio of each relaxation component changes depending on the film composition and the film configuration. Here, the ratio of the relaxing component refers to the ratio of the relaxing component to the total relaxing component of the anisotropic magnetic field. For example, the relaxing component of the anisotropic magnetic field of the magnetic layer is the first anisotropic magnetic field. If the magnetic field H _k1 made of a second anisotropic magnetic field H _k2 Prefecture, the ratio of the first anisotropic magnetic field H _k1 becomes _{H k1 / H k1 + H k2} (= 2 * H k).

When the anisotropic magnetic field of the first magnetic layer (free layer) is relaxed in a direction perpendicular to the direction of the anisotropy initially applied, the first anisotropic magnetic field H _k1 is reduced. The magnetization state after the relaxation differs depending on, for example, the ratio between H _k1 and H _k2 . For example, when the ratio of the first anisotropic magnetic field H _k1 (H _k1 / 2 * H _k ) whose relaxation time is early is large (indicated by a line a in FIG. 1), the first anisotropic magnetic field H _k1 becomes large. After the relaxation, a magnetic field perpendicular to the initial anisotropic magnetic field remains as the magnetization direction of the free layer. On the other hand, the ratio of the first anisotropic magnetic field H _k1 (H
_{When k} 1/2 ^* H _k ) is small (indicated by the line c in FIG. 1), the initial anisotropic magnetic field remains as the magnetization direction of the free layer even after the first anisotropic magnetic field H _k1 is relaxed. . Also, the first
If the proportion of the anisotropic magnetic field H _k1 is assumed 50% of the almost becomes zero is the magnitude of the anisotropy field of the free layer after providing the first anisotropic magnetic field H _k1 is relaxed, apparently It becomes an isotropic film.

As described above, the magnitude of the anisotropic magnetic field of the magnetic layer (for example, the free layer) differs depending on the relaxation time of the anisotropic magnetic field.
Changes over time based on two or more relaxation components. When a magnetoresistive film having such a free layer is used for a magnetic head, the MR ratio is reduced, and a reproduction output varies in a magnetic recording apparatus having such a magnetic head.

The present invention has been accomplished by finding that two or more components exist in the relaxation of the anisotropic magnetic field, and that the relaxation time of the anisotropic magnetic field differs depending on each relaxation component. That is, for example, as shown in FIG.
For anisotropic magnetic field H _k2 are extremely long relaxation time than the first anisotropic magnetic field H _k1, state after relaxation time question is to relax the earlier first anisotropic magnetic field H _k1 is It can be said that it is a magnetically stable state.

As described above, the magnetoresistive effect element of the present invention in which the first relaxation component (first anisotropic magnetic field H _k1 ) whose relaxation time is the earliest is relaxed is the first magnetic layer (free). The magnetization direction of the first magnetic layer (free layer) is stable even when the magnetization directions of the layer and the second magnetic layer (pin layer) are substantially orthogonal to each other. Therefore, according to the magnetoresistive effect element of the present invention, it is possible to suppress a decrease in the MR ratio and the like. It becomes possible to suppress.

Furthermore, most relaxation time Q is earlier first relaxation component according to (first anisotropic magnetic field H _k1) ratio of _{(H k1 / 2 * H k} ), of the magnetic field applied during the initial heat treatment By stabilizing the magnetization direction of the first magnetic layer (free layer) by setting the direction to either the pin layer direction (pin layer priority) or the free layer direction (free layer priority), It can be made substantially perpendicular to the magnetization direction of the magnetic layer (pin layer).

[0028]

Embodiments of the present invention will be described below.

FIGS. 2 and 3 are views showing the structure of an embodiment of a recording / reproducing separation type magnetic head in which the magnetoresistive element of the present invention is applied to a reproducing element section. FIG. 2 is a sectional view of the recording / reproducing separation type magnetic head viewed from the medium facing surface direction, and FIG. 3 is an enlarged sectional view showing the magnetoresistive film portion.

In these figures, reference numeral 11 denotes a substrate,
As the substrate 11, Al ₂ O ₃ having an Al ₂ O ₃ layer
-A TiC substrate or the like is used. On the main surface of such a substrate 11, a lower magnetic shield layer 12 made of a soft magnetic material such as a CoZrNb amorphous alloy, a NiFe alloy, or a FeSiAl alloy is formed. A magnetoresistive film (MR) is formed on the lower magnetic shield layer 12 via a lower reproducing magnetic gap 13 made of a nonmagnetic insulating material such as AlO _x.
A film 14 is formed.

The MR film 14 is formed, for example, as shown in FIG.
A magnetic multilayer in which a first magnetic layer (free layer) 15, a non-magnetic layer 16, a magnetically fixed second magnetic layer (pin layer) 17, and an antiferromagnetic layer 18 in which the magnetization direction is changed by an external magnetic field are sequentially stacked. This is a so-called spin valve film (spin valve GMR film) having a film and exhibiting a giant magnetoresistance effect.

The free layer 15 and the pinned layer 17 have Co
Co alloys such as CoFe alloys and NiFe alloys are used. These may be single-layer films or stacked films. For example, when the free layer 15 is composed of a laminated film, a laminated film of a magnetic film as described above, an amorphous CoZrNb alloy film, a laminated film of a magnetic alloy film obtained by adding various additive elements to a NiFe alloy, and the like, A laminated film of various magnetic films can be applied. In this case, the anisotropic magnetic field H _k of the free layer 15 indicates the anisotropic magnetic field of the entire laminated film.

The nonmagnetic layer 16 is made of Cu, Au, Ag, or an alloy thereof. The antiferromagnetic layer 18 includes an IrMn alloy, a PtMn alloy, a NiMn alloy, Ni
Various antiferromagnetic materials such as O are used. Further, the pinning of the magnetization of the pinned layer 17 is not limited to the exchange coupling with the antiferromagnetic layer 18, but it is also possible to use antiferromagnetic coupling or the like.

In the drawing, reference numeral 19 denotes a base film made of Ta, Ti or the like, and reference numeral 20 denotes a protective film made of a similar material. These are formed as needed. Also, spin valve GM
The structure of the R film 14 is not limited to the structure in which the free layer 15 is arranged on the lower side as shown in FIG. 3, but may be a structure in which the pinned layer 17 is arranged on the lower side.

The magnetization directions of the free layer 15 and the pinned layer 17 are substantially orthogonal to each other. Here, the magnetization (anisotropic magnetic field) of the free layer 15 is determined when the magnetic layer constituting the free layer 15 has two or more types of relaxation components having different relaxation times of the anisotropic magnetic field. The first relaxation component (first anisotropic magnetic field H _k1 ), which has the earliest relaxation time among the relaxation components, is relaxed.

That is, the component in which the anisotropic magnetic field of the free layer 15 has a fast relaxation time (ie, the first anisotropic magnetic field H _k1 ) and the component in which the relaxation time is slow (ie, the second anisotropic magnetic field H _k2 ).
If having the door, as shown in FIG. 1, to relax the first anisotropic magnetic field H _k1, extremely long second anisotropic relaxation time than the first anisotropic magnetic field H _k1 The practical magnetization direction of the free layer 15 is determined based on the magnetic field H _k2 . Therefore, the magnetization directions of the free layer 15 and the pinned layer 17 are stable even though the magnetization directions are substantially orthogonal to each other.

The initial application of the anisotropic magnetic field to the free layer 15 is determined according to the ratio of the first anisotropic magnetic field H _k1 to the total relaxation component of the anisotropic magnetic field. For example, the ratio of the first anisotropic magnetic field H _k1 , for example, H _k1 / H _k1
When + H _k2 (= 2 * H _k ) is 60% or more (60% ≦ H _k1 <100%), after relaxing the first anisotropic magnetic field H _k1 ,
The magnetic field in the direction perpendicular to the initial anisotropic magnetic field is a free layer 1
5 remains as the magnetization direction. Therefore, the direction of the magnetic field applied during the initial heat treatment is set to the pin layer direction (pin layer preferential heat treatment).

Specifically, as shown in FIG. 4, first, the anisotropic magnetic field H is applied to the pinned layer 17 in a predetermined direction at a predetermined temperature.
_{In addition} to applying _k pin, an anisotropic magnetic field H _{k0 is applied} to the free layer 15 in the same direction as the magnetization direction of the pinned layer 17. Next, while applying a magnetic field H in a direction perpendicular to the direction of the anisotropic magnetic field H _k0 applied during the initial heat treatment, the free layer 15 is kept at a temperature equal to or lower than that of the initial heat treatment for a predetermined time. to relieve the first anisotropic magnetic field H _k1. At this time, since the proportion of H _k1 is 60% or more, after relaxing H _k1 , the anisotropic magnetic field H
anisotropic magnetic field of _k0 in the direction substantially perpendicular to the direction H _k free, i.e. free magnetization direction and the magnetization obtained by substantially perpendicular pin layer 17 is layer 1
5 remains as the magnetization direction.

On the other hand, the ratio of the first anisotropic magnetic field H _k1 , for example, H _k1 / H _k1 + H _k2 (= 2 * H _k ) is 40% or less (0% <H _k1 ≦
(40%), the direction of the initial anisotropic magnetic field remains as the magnetization direction of the free layer 15 even after relaxing the first anisotropic magnetic field H _k1 . Therefore, the direction of the magnetic field applied during the initial heat treatment is set to the free layer direction (free layer preferential heat treatment).

More specifically, as shown in FIG. 5, during the initial heat treatment, the anisotropic magnetic field H is applied to the free layer 15 in a predetermined direction at a predetermined temperature (final magnetization direction of the free layer 15). _{Add k0} . Next, while applying a magnetic field H in a direction orthogonal to the direction of the anisotropic magnetic field H _k0 given at the time of the initial heat treatment, that is, in the magnetization direction of the pinned layer 17, it is kept at a temperature equal to or lower than that of the initial heat treatment for a predetermined time. . By this heat treatment, an anisotropic magnetic field H _k pin is applied to the pinned layer 17 in a predetermined direction, and the first anisotropic magnetic field H _k1 of the free layer 15 is relaxed. At this time, since the ratio of H _k1 is 40% or less, even after relaxing H _k1 , the anisotropic magnetic field H _k0 in the same direction as the anisotropic magnetic field H _{k0 applied} during the initial heat treatment is used.
_k free, that is, the magnetization substantially perpendicular to the magnetization direction of the pinned layer 17 remains as the magnetization direction of the free layer 15.

As described above, according to the ratio of the first anisotropic magnetic field H _k1 to the relaxing component of the anisotropic magnetic field of the free layer 15, the heat treatment giving priority to the pinned layer or the free layer is performed. By applying a practical anisotropic magnetic field, the magnetization directions of the free layer 15 and the pinned layer 17 can be easily made to have a substantially orthogonal relationship (operating point bias).
The magnetization direction of the free layer 15 can be stabilized.
Further, the magnitude of the anisotropic magnetic field of the free layer 15 can be controlled by the ratio of the first anisotropic magnetic field H _k1 .
The ratio of the relaxing component of the anisotropic magnetic field in the free layer 15 (for example, H _k1 / 2 * H _k ) is controlled by the type of magnetic material used for the free layer 15 and the thickness ratio when different magnetic films are stacked. be able to.

Further, according to the above-described heat treatment in a magnetic field, even when the pinning temperature of the pinned layer 17 is as high as 300 ° C. or higher, an operating point bias can be easily applied. Further, when the magnetization pinning temperature of the pinned layer 17 is a high temperature, for example, 300 ° C. or higher, the anisotropic magnetic field of the free layer 15 can be applied at a higher temperature. Thermal stability can be further enhanced.

The ratio of the first anisotropic magnetic field H _k1 of the free layer 15 is preferably 60% or more or 40% or less as described above. The ratio of the first anisotropic magnetic field H _k1 is 40%
If the range is <H _k1 <60%, the magnitude of the anisotropic magnetic field finally applied to the free layer 15 becomes too small, and the spin valve GMR film 14 is saturated with a small external magnetic field. Therefore, the reproduction output of the magnetic head is reduced. First anisotropic magnetic field H of free layer 15
The ratio of _k1 is more preferably 70% or more or 30% or less.

The above-mentioned spin valve GMR film 14 has a shape corresponding to a magnetic field detecting section for detecting an external magnetic field such as a signal magnetic field. In other words, the spin valve GMR film 14 has a shape in which a portion deviating from the recording track width is etched away, for example, so that the length has a desired track width. Such a spin valve GMR film 14
A pair of bias magnetic field applying films 21 for applying a bias magnetic field to the spin valve GMR film 14
Are formed. The bias magnetic field applying film 21 is abutted to the spin valve GMR film 14. At this time, the bias magnetic field is applied in the same direction as the anisotropic magnetic field of the free layer 15.

As the bias magnetic field applying film 21, a hard magnetic film or the like is used. Further, the hard bias structure is not limited to the abut junction, and an overlay structure in which a part of the spin valve GMR film 14 is stacked on the bias magnetic field application film 21 or the like can be applied. Furthermore, spin valve G
The bias magnetic field applied to the MR film 14 is not limited to the hard bias, but may be applied by a method such as a current bias or a sal bias.

On the pair of bias magnetic field applying films 21, C
A pair of electrodes 22 made of u, Au, Zr, Ta or the like is formed. A sense current is supplied to the spin valve GMR film 14 by a pair of electrodes 22. The spin valve GMR film 14, a pair of bias magnetic field applying films 21 and a pair of electrodes 22 constitute a GMR reproducing element 23.

On the GMR reproducing element 23, an upper magnetic shield layer 25 is formed via an upper reproducing magnetic gap 24 made of a nonmagnetic insulating material similar to the lower reproducing magnetic gap 13. The upper magnetic shield layer 25 is made of the same soft magnetic material as the lower magnetic shield layer 12. With these components, a shield type GMR as a reproducing head
The head 26 is configured.

On the shield type GMR head 26, a thin film magnetic head 27 is formed as a recording head. The lower write pole of the thin-film magnetic head 27 is formed of the same magnetic layer as the upper magnetic shield layer 25. That is, the upper magnetic shield layer 2 of the shield type MR head 26
Reference numeral 5 also serves as a lower recording magnetic pole of the thin-film magnetic head 27.
On the lower recording magnetic pole 25 also serving as the upper magnetic shield layer,
A recording magnetic gap 28 made of a non-magnetic insulating material such as AlO _x and an upper recording magnetic pole 29 are sequentially formed. Further, a recording coil (not shown) for applying a recording magnetic field to the lower recording magnetic pole 25 and the upper recording magnetic pole 29 is formed behind the medium facing surface. These constitute a thin-film magnetic head 27 as a recording head.

As described above, in the GMR reproducing element 23 in which the relaxation component (first anisotropic magnetic field H _k1 ) in which the relaxation time of the free layer 15 is the fastest is relaxed.
Although the magnetization directions of the pinned layer 17 and the pinned layer 17 are substantially orthogonal to each other, the magnetization direction of the free layer 15 (anisotropic magnetic field)
Is based on a relaxation component (second anisotropic magnetic field H _k2 ) having a slow relaxation time, and is therefore stable against heat applied during head operation. Therefore, the GMR reproducing element 23 has a large MR.
The rate of change can be stably maintained over a long period of time. Further, according to the recording / reproducing separation type magnetic head including such a GMR reproducing element 23, the fluctuation of the reproduction output can be suppressed based on the stabilization of the MR change rate.

The recording / reproducing separation type magnetic head of the above-described embodiment is incorporated in a head slider, and is mounted on, for example, a magnetic head assembly shown in FIG. The magnetic head assembly 50 shown in FIG. 6 has an actuator arm 51 having, for example, a bobbin for holding a drive coil, and the like.
A suspension 5 is provided at one end of the actuator arm 51.
2 are connected.

At the tip of the suspension 52, a head slider 53 having the recording / reproducing separation type magnetic head of the above-described embodiment is attached. The suspension 52 has a lead wire 54 for writing and reading signals, and the lead wire 54 is electrically connected to each electrode of the recording / reproducing magnetic head incorporated in the head slider 53. In the figure, 55 is the magnetic head assembly 5
0 electrode pad. Such a magnetic head assembly 50 is mounted on a magnetic recording device such as a magnetic disk device shown in FIG. 7, for example. FIG. 7 shows a schematic structure of a magnetic disk device 60 using a rotary actuator.

The magnetic disk 61 is mounted on a spindle 62 and is rotated by a motor (not shown) which responds to a control signal from a drive control source (not shown). The magnetic head assembly 50 is mounted such that a head slider 53 mounted on the tip of a suspension 52 records and reproduces information while flying above the magnetic disk 61. When the magnetic disk 61 rotates, the medium facing surface (ABS) of the head slider 53 is moved to the magnetic disk 61.
From the surface with a predetermined flying height (0 to 100 nm).

The actuator arm 51 of the magnetic head assembly 50 is connected to a voice coil motor 63 which is a kind of a linear motor. The voice coil motor 63 includes a drive coil (not shown) wound around a bobbin portion of the actuator arm 51, and a magnetic circuit including a permanent magnet and an opposing yoke disposed to face each other so as to sandwich the drive coil. Actuator arm 5
Numeral 1 is held by ball bearings (not shown) provided at two positions above and below the fixed shaft 64, and is rotatable and slidable by the voice coil motor 63.

In the magnetic disk device 60 as described above, the reproduction output characteristics can be stabilized based on a small change in the MR change rate of the GMR element. Thus, the practicality of the magnetic disk drive using the spin valve GMR element can be greatly improved.

Although the above embodiment has been described using the recording / reproducing separated magnetic head, the present invention is applied to other head structures such as a recording / reproducing integrated magnetic head using a common magnetic yoke for the recording head and the reproducing head. Can be applied. Further, the magnetoresistive element of the present invention is not limited to a magnetic head, but may be a magnetoresistive memory (MRA).
M) and the like.

[0056]

Next, specific examples of the present invention and evaluation results thereof will be described.

Example 1 A magnetic film corresponding to the free layer 15 of the spin valve GMR film 14 shown in FIGS. 2 and 3 was formed on a thermally oxidized silicon substrate by an ordinary RF magnetron sputtering method. The configuration of the magnetic film corresponding to the free layer 15 is Co ₉₀ Fe ₁₀ (3n
m), Ni ₈₀ Fe ₂₀ (5 nm) / Co ₉₀ Fe ₁₀ (3 nm), Co
₈₇ Zr ₅ Nb ₈ (5 nm) / Ni ₈₀ Fe ₂₀ (2 nm), Co ₈₇ Z
r ₅ Nb ₈ (5 nm) / Ni ₈₀ Fe ₂₀ (2 nm) / Co ₉₀ Fe ₁₀
(3 nm). The composition of each alloy is at%. The magnetic film corresponding to each free layer was formed on a 5 nm-thick Ta underlayer, and then a 5 nm-thick Ta protective layer was formed on the outermost surface.

Each magnetic film produced in this way is subjected to a heat treatment in a magnetic field heat treatment furnace in a vacuum at a temperature of 270 ° C., a holding time of 1 hour and an external magnetic field of 5 kOe, so as to be oriented in the direction shown in FIG. Was given anisotropy. 8, 71 denotes a substrate, 72 is a magnetic film, an external magnetic field H ₁ is obtained by applying the initial heat treatment described above (= 5kOe), - H _k is the anisotropy field imparted by the initial heat treatment.

Next, as shown in FIG. 8B, a magnetic field H ₂ (= 〜1 kOe) is applied to the anisotropic magnetic film 72 in a direction perpendicular to the initial external magnetic field H _1. Apply and
Raise the temperature to a predetermined temperature (260 ° C and 240 ° C in this example) and hold at each temperature for a predetermined time (approx.
30 hours). FIG. 8C shows a state after the anisotropic magnetic field (−H _k ) of the magnetic film 72 is relaxed, and the anisotropic magnetic field orthogonal to the initial anisotropic magnetic field (−H _k ). (H
_k = | −H _k |).

The direction and magnitude of the anisotropic magnetic field of the magnetic film subjected to the application and relaxation of the anisotropic magnetic field were measured by a vibrating magnetometer (VSM). Based on the obtained H _k relaxation behavior under the following assumptions, the rate of rapid relaxation (H _k1 / 2 * H _k ) and the relaxation time were obtained at each temperature, and the relaxation time under other temperature conditions was estimated.

Since the relaxation behavior of the anisotropic magnetic field H _k can be predicted by assuming two relaxation modes, fitting at each temperature can be performed by the following equations.

Formula: H _k (2 * H _k 2 * H _k1 ) * exp (M ₀ / τ
₂ ) 2 * H _k1 * exp (−M ₀ / τ ₁ ) Here, H _k is the magnitude of the initially applied anisotropic magnetic field, 2 *
H _k is the amplitude width in relaxation (ie, the magnitude of anisotropy from the initially applied direction to the perpendicular direction), H _k1 is the anisotropic magnetic field for fast relaxation, H _k2 is the anisotropic magnetic field for slow relaxation, τ ₁ is the fast relaxation time and τ ₂ is the slow relaxation time.

An example of this fitting result (Ni ₈₀ Fe ₂₀ (5
nm) / Co ₉₀ Fe ₁₀ (3 nm)) is shown in FIG. From this figure, even if the relaxation temperature changes, the ratio of the quick relaxation component (H _k1
/ 2 * H _k ) does not change, and it can be seen that the relaxation time (τ ₁ , τ ₂ ) becomes longer as the relaxation temperature decreases. Therefore, FIG.
The reciprocal of the relaxation time and temperature of the membrane used for the fitting were plotted. The relaxation time at a temperature, which is plotted in this way, is estimated, and by using this relaxation time and the ratio of the fast relaxation component of the anisotropic magnetic field ( _Hk1 / 2 * _Hk ), the relaxation behavior at that temperature can be estimated. Can be predicted. FIG.
FIG. 11 shows the relaxation behavior of the anisotropic magnetic field predicted based on the relaxation time at 0 to 150 ° C.

Table 1 shows the anisotropic magnetic field and fast relaxation component (first anisotropic magnetic field H) of each of the above magnetic films (corresponding to the free layer).
_k1 ) ( _Hk1 / 2 * _Hk ) and the magnitude of the anisotropic magnetic field at the end of the quick relaxation. In the table, the sign of "-" is described before the magnitude of the anisotropic magnetic field because the anisotropy is given in a direction orthogonal to the direction of the initially applied anisotropic magnetic field. Means that. Further, Table 1 shows that Co ₈₇ Zr ₅ Nb ₈ (a
t%) is also described.

[0065]

[Table 1] Each magnetic film of the first embodiment has a first anisotropic magnetic field H _k1.
Ratio of _{(H k1 / 2 * H k} ) is not less than 60%, sufficient as a magnetic anisotropy field size also free layer at the time the relaxation of the first anisotropic magnetic field H _k1 is completed Met. FIG. 12 shows that when the film configuration is Ni ₈₀ Fe ₂₀ / Co ₉₀ Fe ₁₀ ,
The relationship between the film thickness ratio and the ratio of the quick relaxation component H _k1 is shown. As described above, the magnitude of the anisotropic magnetic field of the free layer and the ratio of the quick relaxation component (H _k1 / 2 * H _k ) change depending on the film composition and the film configuration (film thickness ratio).

In order to use each magnetic film having the above H _k1 ratio of 60% or more as a free layer, a heat treatment as shown in FIG. 4 was performed. That is, first, a preferential heat treatment was performed in the direction of the pinned layer, and a magnetic field was applied to the free layer in a direction perpendicular to the direction, thereby giving anisotropy at a temperature lower than the heat treatment temperature of the pinned layer. This heat treatment relaxes the component whose relaxation time of the anisotropic magnetic field is short. By such a heat treatment in a magnetic field, the operating point bias of the spin valve GMR film was set. FIG.
By using a magnetic film having the relaxation behavior as shown in (1) as the free layer, it is possible to apply anisotropic magnetic fields necessary and sufficient to obtain a stable output to the pinned layer and the free layer, respectively. The magnetization (anisotropic magnetic field) of the layer could be stabilized.

Example 2 In the same manner as in Example 1, a magnetic film corresponding to the free layer was formed on a thermally oxidized silicon substrate by an ordinary RF magnetron sputtering method. The configuration of the magnetic film corresponding to the free layer 15 is Ni ₈₀ Fe ₂₀ (3 nm), Ni ₈₀ Fe ₂₀ (10 nm) / Co ₉₀
Fe ₁₀ (1 nm) and Ni ₇₈ Fe ₁₇ Cr ₅ (10 nm). The magnetic film corresponding to each free layer was formed on a 5 nm-thick Ta underlayer, and then a 5 nm-thick Ta protective layer was formed on the outermost surface. After applying an anisotropic magnetic field to each magnetic film in the same manner as in Example 1, the relaxed state of the anisotropic magnetic field was examined. Table 2 shows the results.

[0068]

[Table 2] Anisotropic magnetic field of the magnetic films mentioned above is the magnitude of 2.25~ 5.0Oe, early rate of relaxation component _{H k1 (H k1 / 2 *} H k) is
The range was 30-33%. In addition, the anisotropic magnetic field after the completion of the quick relaxation had a sufficient value.

In order to use each magnetic film having such a ratio of H _k1 of 40% or less as a free layer, a heat treatment as shown in FIG. 5 was performed. That is, after performing a preferential heat treatment in the direction of the free layer, anisotropy is imparted to the pinned layer at a temperature lower than the initial heat treatment temperature while applying a magnetic field in a direction perpendicular thereto, and the anisotropic magnetic field of the free layer is relaxed. The anisotropy of the free layer was determined by relaxing the component whose time was earlier. By such a heat treatment in a magnetic field, the operating point bias of the spin valve GMR film was set. As a result, an anisotropic magnetic field necessary and sufficient to obtain a stable output can be applied to each of the pinned layer and the free layer, and furthermore, the magnetization (anisotropic magnetic field) of the free layer can be stabilized. Was.

Example 3 In the same manner as in Example 1, the spin valve GMR film 14 and the GMR element (23) shown in FIGS.

The film configuration of the spin valve GMR film 14 is as follows: Sample A: Ta (5 nm) / ((Ni ₈₄ Fe ₁₆ ) ₉₆ Cr ₄ (10 nm)
/ Co ₉₀ Fe ₁₀ (3 nm) 15 / Cu (3 nm) 16 / Co ₉₀ F
e ₁₀ (2 nm) 17 / Ir ₂₀ Mn ₈₀ (7 nm) 18 / Ta (5 nm)
Sample B: Ta (5 nm) / (Ni ₈₀ Fe ₂₀ (5 nm) / Co
₉₀ Fe ₁₀ (3 nm) 15 / Cu (3 nm) 16 / Co ₉₀ Fe ₁₀ (2
Sample 17: Ir ₂₀ Mn ₈₀ (7 nm) 18 / Ta (5 nm), Sample C: Ta (5 nm) / (Ni ₈₀ Fe ₂₀ (10 nm) / Co ₉₀ Fe ₁₀
(1 nm)) 15 / Cu (3 nm) 16 / Co ₉₀ Fe ₁₀ (2 nm) 17
/ Ir ₂₀ Mn ₈₀ (7 nm) 18 / Ta (5 nm). Samples A and B were subjected to a heat treatment giving priority to the pin layer in the same manner as in Example 1.
Sample C was subjected to a heat treatment giving priority to the free layer in the same manner as in Example 2.

As a comparative example with the present invention, Ta (5n
m) / (Co ₈₇ Zr ₅ Nb ₈ (5 nm) / Ni ₈₀ Fe ₂₀ (3 nm)
/ Co ₉₀ Fe ₁₀ (1 nm) 15 / Cu (3 nm) 16 / Co ₉₀
Fe ₁₀ (2 nm) 17 / Ir ₂₀ Mn ₈₀ (7 nm) 18 / Ta (5n
m) (Sample D) Spin valve GMR film and GM having structure
An R element was manufactured.

The MR ratio of each GMR element thus obtained was measured by a DC four-terminal method, and the change with time was examined.
The result is shown in FIG. The evaluation of the change over time was performed at 200 ° C., and the time was set to an integrated time of 20 hours.

As is clear from FIG. 13, the GM of the comparative example
The R element (sample D) has a large change with time, and the MR change rate is greatly deteriorated from 7.5% to 5.0% only after being left at 200 ° C. for 1 hour. Has fallen to 4.3%. A magnetic disk device equipped with such a GMR element has a large fluctuation in reproduction output and is not practical.

On the other hand, the GMR elements (samples A, B, and C) according to Example 3 showed very little change with time, and the MR change rate hardly decreased even after 20 hours. The MR ratio of Sample A was 8.2% at the initial value, and 1 hour later.
8.0%, 7.9% after 4 hours and 7.9% after 20 hours. The MR change rates of Sample B are 8.0%, 7.7%, 7.6%, and 7.6%, respectively, and the MR change rates of Sample C are 7.5%, 7.3%, 7.0%, and
It was 6.9%. By mounting such a GMR element in a magnetic disk drive, fluctuations in the reproduction output can be significantly suppressed.

[0076]

As described above, according to the magnetoresistance effect element of the present invention, when the magnetization directions of the two magnetic layers of the magnetoresistance effect film are, for example, orthogonal, the magnetization direction is changed by an external magnetic field. Since the anisotropic magnetic field of the magnetic layer to be made can be stabilized, a large MR change rate can be stably maintained for a long period of time. According to the magnetic head or the magnetic recording device using such a magnetoresistive element, characteristics such as reproduction output and reliability thereof can be improved.

[Brief description of the drawings]

FIG. 1 is a view for explaining a relaxation behavior of an anisotropic magnetic field of a magnetic layer.

FIG. 2 is a cross-sectional view showing a structure of an embodiment of a recording / reproducing separation type magnetic head in which a magnetoresistive element of the present invention is applied to a reproducing element.

FIG. 3 is an enlarged sectional view showing a magnetoresistive film portion of the magnetoresistive head shown in FIG. 2;

FIG. 4 is a diagram for explaining a pin layer preferential heat treatment of a spin valve film.

FIG. 5 is a diagram illustrating a free layer preferential heat treatment of the spin valve film.

FIG. 6 is a perspective view showing a configuration example of a magnetic head assembly using the magnetic head of the present invention.

FIG. 7 is a perspective view showing a configuration example of a magnetic disk device using the magnetic head of the present invention.

FIG. 8 is a diagram for explaining a method for evaluating the relaxation of the anisotropic magnetic field of the magnetic layer.

FIG. 9 is a diagram illustrating an example of a relaxation behavior of an anisotropic magnetic field of a magnetic film corresponding to a free layer in the first embodiment.

FIG. 10 is a diagram showing an example of the relationship between the relaxation temperature of the anisotropic magnetic field of the magnetic film corresponding to the free layer and the temperature in Example 1.

FIG. 11 is a cross-sectional view of a magnetic film equivalent to a free layer in Example 1.
It is a figure which shows the relaxation prediction of the anisotropic magnetic field at 150 degreeC.

FIG. 12 is a diagram illustrating an example of a relationship between a film configuration of a magnetic film corresponding to a free layer and a fast relaxation component (H _k1 ) according to the first embodiment.

FIG. 13 is a diagram showing a change over time of an MR change rate of a GMR element in Example 3.

[Explanation of symbols]

 14 spin valve GMR film 15 free layer 16 nonmagnetic layer 17 pinned layer 23 GMR reproducing element 26 shielded GMR head 50 magnetic head assembly 53 head slider 60 Magnetic disk drive

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Katsuhiko Konoi, Inventor 72 Horikawa-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Inside Higashishiba Kawasaki Works

Claims (10)

[Claims] 1. A first method in which a magnetization direction is changed by an external magnetic field.
Supplying a sense current to the magnetoresistive film, the magnetoresistive film having a first magnetic layer, a second magnetic layer laminated via the first magnetic layer and the nonmagnetic layer, and fixed with magnetization; Wherein the first magnetic layer is different in relaxation time of the anisotropic magnetic field.
A magnetoresistive element having at least one kind of relaxation component, wherein the first relaxation component having the fastest relaxation time among the two or more kinds of relaxation components is relaxed. 2. The magnetoresistive element according to claim 1, wherein the first magnetic layer has a ratio of the first relaxing component of 60% or more to a total relaxing component of the anisotropic magnetic field. A magnetoresistive effect element characterized in that: 3. The magnetoresistance effect element according to claim 1, wherein the first magnetic layer has a ratio of the first relaxing component of 40% or less to a total relaxing component of the anisotropic magnetic field. A magnetoresistive effect element characterized in that: 4. The magnetoresistance effect element according to claim 2, wherein an anisotropic magnetic field is applied to said first magnetic layer in a direction substantially the same as a magnetization direction of said second magnetic layer, and said ratio is adjusted. Relaxes the first moderating component by more than 60%,
A magnetoresistive element, wherein the magnetization direction of the first magnetic layer is substantially perpendicular to the magnetization direction of the second magnetic layer. 5. The magnetoresistance effect element according to claim 3, wherein an anisotropic magnetic field is applied to said first magnetic layer in a direction substantially perpendicular to a magnetization direction of said second magnetic layer, and said ratio is adjusted. Reduces the first moderating component by more than 40%,
A magnetoresistive element, wherein the magnetization direction of the first magnetic layer is substantially perpendicular to the magnetization direction of the second magnetic layer. 6. The magnetoresistive element according to claim 1, further comprising a bias magnetic field applying film for applying a bias magnetic field to said magnetoresistive effect film. Magnetoresistive element. 7. The lower magnetic shield layer, and formed on the lower magnetic shield layer with a lower reproducing magnetic gap interposed therebetween.
7. A magnetic head, comprising: the magnetoresistive element according to claim 1; and an upper magnetic shield layer formed on the magnetoresistive element via an upper reproducing magnetic gap. 8. The magnetoresistive element according to claim 1, wherein the lower magnetic shield layer is formed on the lower magnetic shield layer via a lower reproducing magnetic gap. A read head having an upper magnetic shield layer formed on the magnetoresistive element via an upper read magnetic gap; a lower magnetic pole shared with the upper magnetic shield layer; A recording / reproducing separation type magnetic head, comprising: a recording magnetic gap formed in the recording magnetic gap; and a recording head having an upper magnetic pole provided on the recording magnetic gap. 9. A magnetic head assembly comprising: a head slider having the magnetic head according to claim 8; and an arm having a suspension on which the head slider is mounted. 10. A magnetic recording medium, and a head slider provided with the magnetic head according to claim 8, which writes a signal to the magnetic recording medium by a magnetic field and reads a signal by a magnetic field generated from the magnetic recording medium. A magnetic recording device, characterized in that: