JPH10233540A - Magneto-resistance effect film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress production of Barkhausen noise without providing a magnetic domain control layer beside, in the plane of, a magneto-resistance effect film, for allowing more minute magneto-resistance effect element. SOLUTION: A first and a second ferromagnetic layers 2 and 4 are provided with a non-magnetic conductive layer 3, and a first anti-ferromagnetic layer 1 combined magnetically to the first ferromagnetic layer 2 and a second anti- ferromagnetic layer 5 combined magnetically to the second ferromagnetic layer 4 are provided, and the orientation of magnetic anisotropy of the first ferromagnetic layer 2 and the first anti-ferromagnetic layer 1 substantially differs from that of the second ferromagnetic layer 4 and the second anti-ferromagnetic layer 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a giant magnetoresistive film having at least two ferromagnetic layers sandwiching a nonmagnetic conductive layer as a constituent unit, and has a novel structure. It relates to an effect film.

[0002]

2. Description of the Related Art At least two layers with a nonmagnetic conductive layer interposed therebetween.
In a giant magnetoresistive film having a ferromagnetic layer as a constituent unit, the electrical conductivity changes in accordance with the state of magnetization alignment of the two ferromagnetic layers. Can be detected.

A giant magnetoresistive film called a spin valve type is known as one type of the conventional magnetoresistive film. In a spin-valve magnetoresistive film, an antiferromagnetic layer is magnetically coupled to one ferromagnetic layer to pin the magnetization, and the other ferromagnetic layer is set in a free state. The magnetization state of the magnetic layer is changed by the application of an external magnetic field, and the external magnetic field is detected using the change in the resistance value generated in the magnetization process.

When the magnetization state of the non-pinned ferromagnetic layer changes in response to the application of an external magnetic field, a magnetic domain is generated in the ferromagnetic layer. When the magnetic domain moves, the magnetic resistance changes discontinuously, So-called Barkhausen noise occurs. In order to suppress the generation and movement of magnetic domains that cause such Barkhausen noise, a magnetic domain control layer made of a hard material is provided on the inner side of the surface of the magnetoresistive film to generate magnetic domains in the ferromagnetic layer. And suppressing the movement has been generally performed conventionally.

[0005]

However, in recent years,
In response to high-density recording, the track width of the magnetoresistive element is required to be fine. And the production yield may be reduced. In addition, the present inventors have noticed that in the conventional structure, the portion of the magnetoresistive film in the vicinity of the magnetic domain control layer does not function as an effective detection portion, so that sufficient sensitivity is not exhibited. did.

SUMMARY OF THE INVENTION It is an object of the present invention to suppress the generation of Barkhausen noise without providing a magnetic domain control layer inside the surface of a magnetoresistive effect film, and to make the magnetoresistive effect element finer. It is another object of the present invention to provide a novel structure of a magnetoresistive effect film.

[0007]

The magnetoresistive film of the present invention is a magnetoresistive film for detecting a change in an external magnetic field by a change in magnetoresistance. The magnetoresistive film sandwiches a nonmagnetic conductive layer and a nonmagnetic conductive layer. And a first antiferromagnetic layer magnetically coupled to the first ferromagnetic layer and a second antiferromagnetic layer magnetically coupled to the second ferromagnetic layer. A first ferromagnetic layer and a first antiferromagnetic layer, and a magnetic anisotropy direction of the second ferromagnetic layer and the second antiferromagnetic layer. It is characterized in that the direction is substantially different.

In the present invention, the magnetization state of one of the first ferromagnetic layer and the second ferromagnetic layer having different directions of magnetic anisotropy is changed by applying an external magnetic field. Then, a change in the external magnetic field is detected by measuring a change in electric conductivity caused by the change.

Since both the first ferromagnetic layer and the second ferromagnetic layer are in a magnetically coupled state with the antiferromagnetic layer, even if the magnetization state of any of the ferromagnetic layers changes, the ferromagnetic layer will not change. , The occurrence of magnetic domains is suppressed, the discontinuous change in electric conductivity due to the movement of the magnetic domains can be suppressed, and the generation of Barkhausen noise can be suppressed.

The arrangement of the first and second antiferromagnetic layers in the present invention is not particularly limited, but generally, the first antiferromagnetic layer is located between the nonmagnetic conductive layer side of the first ferromagnetic layer. The second antiferromagnetic layer is provided on the opposite surface, and the second antiferromagnetic layer is provided on the surface of the second ferromagnetic layer opposite to the nonmagnetic conductive layer side.

In a limited embodiment according to the present invention, the direction of the easy axis of the first ferromagnetic layer induced by magnetic coupling with the first antiferromagnetic layer is aligned with the direction of the external magnetic field, The direction of the hard axis of the second ferromagnetic layer induced by magnetic coupling with the second antiferromagnetic layer is aligned with the direction of the external magnetic field. The first ferromagnetic layer, in which the direction of the external magnetic field and the direction of the easy axis of magnetization are substantially the same, exhibits a magnetization pinned state with a change in the external magnetic field with unidirectional bias anisotropy. On the other hand, in the second ferromagnetic layer in which the direction of the hard axis is almost the same as the direction of the external magnetic field,
The magnetization state can be changed under the influence of the change in the external magnetic field. Therefore, a change in the external magnetic field can be detected from a change in the electrical conductivity when the magnetization state changes.
Since the second ferromagnetic layer is in a magnetic coupling state with the second antiferromagnetic layer, the generation of magnetic domains is suppressed, so that the discontinuous change in electric conductivity due to the movement of the magnetic domains can be suppressed. Generation of noise can be suppressed.

In general, the direction of the easy axis of magnetization of the ferromagnetic layer and the direction of the hard axis of magnetization are substantially orthogonal to each other. Therefore, in the above embodiment, the direction of the easy axis of magnetization of the first ferromagnetic layer is the second direction. Are substantially orthogonal to the direction of the easy axis of the ferromagnetic layer.

In the present invention, the first antiferromagnetic layer and the second antiferromagnetic layer
By forming at least one of the antiferromagnetic layers from the oxide antiferromagnetic material, the current flowing in the magnetoresistive film can be concentrated at the interface between the nonmagnetic conductive layer and the ferromagnetic layer. And the detection sensitivity can be increased.
Examples of the oxide antiferromagnetic material include NiO, Co
O, Fe ₂ O _{3 and the} like. In a general structure of a magnetoresistive element, an electrode is often provided above both sides of the magnetoresistive film, so that the first antiferromagnetic layer and the second antiferromagnetic layer have the opposite antiferromagnetic layer. The magnetic layer preferably has good conductivity. Therefore, when an oxide antiferromagnetic material that does not exhibit good conductivity is used, it is preferable to use an oxide antiferromagnetic material for the antiferromagnetic layer on the side opposite to the surface side, that is, on the substrate side.

The ferromagnetic layer used in the magnetoresistive film of the present invention is not particularly limited as long as it is a layer formed of a ferromagnetic material whose Curie temperature is higher than the element use temperature. Specific examples include a laminated film of a NiFe layer and a Co layer, a NiFe layer, a Co layer, and a ferromagnetic layer made of an alloy thereof. The thickness of the ferromagnetic layer is generally 1
About 10 nm.

The non-magnetic conductive layer used in the magnetoresistive film of the present invention is not particularly limited as long as it is a non-magnetic material at an element operating temperature and has excellent conductivity. , An Ag layer, and the like. The thickness of the nonmagnetic conductive layer is generally about 1 to 5 nm.

The antiferromagnetic layer used in the magnetoresistive film of the present invention is not particularly limited as long as it is a layer formed of an antiferromagnetic material whose Neel temperature (described later) is higher than the device operating temperature. Not something. Specifically, in addition to the above-described oxide-based antiferromagnetic material layer, a FeMn layer, a NiMn layer, and the like can be given. The thickness of the antiferromagnetic layer is generally 5 to 25 nm.
It is about.

The magnetoresistance effect element of the present invention is generally formed on a substrate, but the material of the substrate is not particularly limited as long as it is non-magnetic. For example, Si, TiC, Al ₂
Substrates such as O ₃ and glass are used.

A first manufacturing method according to the present invention is a method capable of manufacturing the above-described magnetoresistive film of the present invention, and comprises a nonmagnetic conductive layer, first and second ferromagnetic layers, and a first ferromagnetic layer.
Forming a laminated film having a first ferromagnetic layer and a first antiferromagnetic layer by heating the laminated film to a first predetermined temperature and applying a magnetic field. A first magnetic field applying step of aligning the direction of the magnetic anisotropy of the magnetic layer with the direction of the magnetic anisotropy of the second ferromagnetic layer and the second antiferromagnetic layer in substantially the same direction; The first ferromagnetic layer and the first antiferromagnetic layer are set by setting the film to a second predetermined temperature lower than the first predetermined temperature and applying a magnetic field in a direction different from the first magnetic field applying step. Or the direction of magnetic anisotropy of either the direction of magnetic anisotropy or the direction of magnetic anisotropy of the second ferromagnetic layer and the second antiferromagnetic layer is aligned with the different magnetic field application direction. 2 magnetic field application steps.

According to the first manufacturing method of the present invention, the heat treatment is performed at a predetermined temperature after forming the laminated film,
The direction of the magnetic anisotropy of the first antiferromagnetic layer and the second antiferromagnetic layer is set. Such a manufacturing method is useful when a high-temperature heat treatment is performed in a manufacturing process after the formation of the magnetoresistive film. In general, the formation of a thin-film magnetic head involves a high-temperature treatment step. Therefore, when forming a composite type magnetic head in which a thin-film magnetic head is formed after forming a magnetoresistive head, the first manufacturing method of the present invention uses Will be useful.

In the first manufacturing method of the present invention, the first anti-ferromagnetic property is changed by changing the heating temperature and the direction of the magnetic field when the magnetic field is applied in the first magnetic field applying step and the second magnetic field applying step. The direction of the magnetic anisotropy of the layer and the second antiferromagnetic layer is changed. Note that the first and second ferromagnetic layers are magnetically coupled to the first and second antiferromagnetic layers, respectively, so that the first and second antiferromagnetic layers are magnetically coupled to each other. By setting the direction of the magnetic anisotropy of the ferromagnetic layer to a predetermined direction, the direction of each magnetic anisotropy is determined.

In the first manufacturing method of the present invention, generally, antiferromagnetic materials having different blocking temperatures are used for the first antiferromagnetic layer and the second antiferromagnetic layer. Here, the blocking temperature is a temperature at which one-way anisotropy (bias magnetic field application) disappears, and differs depending on a material, a film thickness, and the like. Therefore, the blocking temperature is an index for evaluating the thermal stability of the antiferromagnetic material. The first predetermined temperature and the second predetermined temperature in the first manufacturing method of the present invention are a temperature using such a blocking temperature as an index,
That is, the temperature is set in consideration of the temperature at which the thermal fluctuation of the spins constituting the antiferromagnetic material increases and the state becomes magnetically unstable (hereinafter, referred to as “magnetic instability temperature”). By temporarily heating above the magnetic instability temperature and applying a magnetic field in a predetermined direction and cooling to below the magnetic instability temperature, the direction of the magnetic anisotropy of the antiferromagnetic layer is changed by the magnetic field. The direction can be substantially the same as the application direction.

In the first manufacturing method of the present invention, generally, the first predetermined temperature in the first magnetic field applying step is the same as that of the first antiferromagnetic layer and the second antiferromagnetic layer. A temperature higher than the stabilization temperature, and a second temperature in the second magnetic field applying step is lower than a magnetic destabilization temperature of one of the first antiferromagnetic layer and the second antiferromagnetic layer; The temperature is higher than the other magnetic instability temperature.

In the first magnetic field applying step, a magnetic field is applied to the first and second antiferromagnetic layers in the same direction, respectively.
The directions of the magnetic anisotropy are aligned in substantially the same direction. In the second magnetic field applying step, the direction of the magnetic anisotropy in the first magnetic field applying step is maintained for the antiferromagnetic layer having the magnetic instability temperature or lower and the magnetic instability temperature or higher. By applying a magnetic field to only the anti-ferromagnetic layer in the direction different from the first magnetic field applying step, the direction of the magnetic anisotropy is aligned in that direction.

FIG. 3 shows a Zr layer (thickness 4 nm) as a base layer, a NiFe layer (thickness 3 nm) as a ferromagnetic layer, and an IrMn layer (thickness 10 nm) as an antiferromagnetic layer on a silicon substrate. FIG. 6 is a diagram showing a blocking temperature in a laminated film in which are sequentially laminated. As shown in FIG. 3, the anisotropic bias magnetic field decreases as the temperature rises, and at 350 ° C., the anisotropic bias magnetic field, that is, the unidirectional anisotropy disappears.

One of the techniques for setting different blocking temperatures in the first antiferromagnetic layer and the second antiferromagnetic layer is as follows.
In this method, antiferromagnetic materials having different Neel temperatures are used as the antiferromagnetic materials used in the respective antiferromagnetic layers. The Neel temperature is a transition temperature of an antiferromagnetic material from an antiferromagnetic state to a paramagnetic state. Table 1 shows the Neel temperatures of various antiferromagnetic materials.

[0026]

[Table 1]

In general, the blocking temperature is proportional to the Neel temperature, with higher Neel temperatures generally showing higher blocking temperatures. Further, even when the same antiferromagnetic material is used, the blocking temperature can be changed depending on the film thickness. FIG. 4 shows a laminated film in which a Zr layer (thickness: 4 nm) as a base layer, a NiFe layer (thickness: 3 nm) as a ferromagnetic layer, and an IrMn layer as an antiferromagnetic layer are stacked on a silicon substrate. 4 shows the blocking temperature, and shows a change in the blocking temperature when the thickness of the IrMn layer as the antiferromagnetic layer is changed. As shown in FIG. 4, since the blocking temperature changes depending on the thickness of the antiferromagnetic layer, the blocking temperature can be adjusted by changing the thickness of the antiferromagnetic layer.

As described above, the first antiferromagnetic layer and the second antiferromagnetic layer
The blocking temperature of the antiferromagnetic layer and the magnetic destabilization temperature that changes in conjunction therewith can be adjusted by appropriately setting the antiferromagnetic material or film thickness used for forming the antiferromagnetic layer. .

According to the first manufacturing method of the present invention, the direction of the magnetic anisotropy of the first antiferromagnetic layer and the direction of the magnetic anisotropy of the second antiferromagnetic layer are different from each other. Can be aligned. In addition, such alignment of the direction of the magnetic anisotropy can be performed after the formation of the stacked film, as described above.

A second manufacturing method according to the present invention is a method capable of manufacturing the above-mentioned magnetoresistive effect film of the present invention, and includes a step of forming a first antiferromagnetic layer and a second antiferromagnetic layer. Forming a first antiferromagnetic layer and a second antiferromagnetic layer having magnetic anisotropy in different directions by applying respective magnetic fields in different directions. This is a manufacturing method for forming.
For example, when forming a first antiferromagnetic layer, a magnetic field is applied in one direction, and when forming a second antiferromagnetic layer, a magnetic field is applied in a direction substantially orthogonal to the first antiferromagnetic layer. Apply a magnetic field. Thereby, the direction of the magnetic anisotropy of the first ferromagnetic layer and the first antiferromagnetic layer is substantially equal to the direction of the magnetic anisotropy of the second ferromagnetic layer and the second antiferromagnetic layer. It is possible to obtain a magnetoresistive effect film which is orthogonal to each other.

According to the second manufacturing method, the direction of the magnetic anisotropy of the antiferromagnetic layer is set by applying a magnetic field during film formation. Therefore, there is no need to use antiferromagnetic layers having different blocking temperatures as in the first manufacturing method in which a magnetic field is applied after the film is formed. However, if the heat treatment is performed at a temperature equal to or higher than the magnetic instability temperature of the antiferromagnetic layer after forming the stacked film, the magnetic anisotropy is lost.

[0032]

FIG. 1 is a sectional view showing a magnetoresistive film according to an embodiment of the present invention. As shown in FIG. 1, a first ferromagnetic layer 2 and a second ferromagnetic layer 4 are provided so as to sandwich the nonmagnetic conductive layer 3, and are magnetically coupled to the first ferromagnetic layer 2. The first antiferromagnetic 1
And a second antiferromagnetic layer 5 is provided outside thereof so as to be magnetically coupled to the second ferromagnetic layer 4.

FIG. 2 is a perspective view showing the direction of the magnetic anisotropy of the magnetoresistive film shown in FIG. As shown in FIG. 2, the direction 2a of the magnetic anisotropy of the first antiferromagnetic layer 1 and the first ferromagnetic layer 2 is the same as that of the second ferromagnetic layer 4 and the second antiferromagnetic layer 5. They are aligned in a direction different from the magnetic anisotropy direction 4a. In this embodiment, the direction 2a of the magnetic anisotropy of the first antiferromagnetic layer 1 and the first ferromagnetic layer 2 is substantially the same as the direction 6 of the external magnetic field. The direction 4a of the magnetic anisotropy of the second ferromagnetic layer 4 and the second antiferromagnetic layer 5 is substantially orthogonal to the direction 6 of the external magnetic field. Therefore,
The direction of the easy axis of magnetization of the first ferromagnetic layer 2 is the same as the direction 2a of the magnetic anisotropy, and the direction of the easy axis of magnetization of the second ferromagnetic layer 4 is the same as the direction 4a of the magnetic anisotropy. is there. Also,
In the second ferromagnetic layer, the direction of the hard axis that is generally orthogonal to the direction of the easy axis is orthogonal to the direction 4a of the magnetic anisotropy.

Therefore, the direction of the easy axis of the first ferromagnetic layer 2 and the direction 6 of the external magnetic field are substantially the same, and the direction of the hard axis of the second ferromagnetic layer 4 and the direction 6 of the external magnetic field are different from each other. Are in substantially the same direction.

The first ferromagnetic layer 2 in which the direction of the axis of easy magnetization and the direction 6 of the external magnetic field are almost the same, shows a pinned state with respect to a change in the external magnetic field. In contrast,
In the second ferromagnetic layer 4 in which the direction of the hard axis is almost the same as the direction 6 of the external magnetic field, the magnetization state changes due to the influence of the external magnetic field. Therefore, when the magnetization state changes, the electrical conductivity changes, and by detecting this, the change in the external magnetic field can be detected.

The second ferromagnetic layer 4 in which the magnetization state changes,
Since the magnetic coupling is performed by the second antiferromagnetic layer 5, even when the magnetization state changes, the generation of magnetic domains can be suppressed, and the discontinuous change in electrical conductivity due to the movement of the magnetic domains can be suppressed. The occurrence of Barkhausen noise can be suppressed.

Hereinafter, the present invention will be described with reference to more specific examples. Example 1 A magnetoresistive film 10 having a laminated structure shown in FIG. 5 was produced. As the substrate 18, a silicon substrate whose surface was oxidized was used. On this substrate 18, a Ta layer (thickness: 5 nm) as a base film 17, a Ni ₅₀ Mn ₅₀ layer (thickness: 5 nm) as a second antiferromagnetic layer 15, and a second ferromagnetic layer 14 Ni ₈₀ Fe ₂₀ layer (film thickness 2 nm), nonmagnetic conductive layer 1
Cu layer 3 (thickness: 2 nm) as first ferromagnetic layer 12
A Ni ₈₀ Fe ₂₀ layer (2 nm thick) as a first anti-ferromagnetic layer 11, an Ir ₂₀ Mn ₈₀ layer (10 nm thick), and a Ta layer (5 nm thick) as a protective film 16 in the order of DC magnetron. It was formed by lamination by a sputtering method. The ultimate vacuum before sputtering is 2 × 10 ⁻⁷ Torr or less, and the Ar gas pressure during sputtering is 10 mTorr.
r, the sputtering speed was 0.2 to 1 nm / sec.

After manufacturing the laminated film as described above, as shown in FIG. 6, a magnetic field of 1 kOe is applied in the direction A to
The heat treatment was performed at 280 ° C. for 5 hours in a vacuum of × 10 ⁻⁶ Torr or less. The magnetic instability temperature of the first antiferromagnetic layer 11 is 200 ° C., and the second antiferromagnetic layer 15
Has a magnetic instability temperature of 250 ° C. In the step shown in FIG. 6, the heat treatment is performed at 280 ° C. higher than these temperatures. After the heat treatment at 280 ° C. for 5 hours, the temperature was gradually lowered and cooled. Thereby, as shown in FIG. 6, the direction 11a of the magnetic anisotropy of the first antiferromagnetic layer 11 and the direction 15a of the magnetic anisotropy of the second antiferromagnetic layer 15
Both directions are almost the same as the direction A, which is the magnetic field application direction.

Next, in the cooling step, the sample temperature was set to 2
When the temperature reached 30 ° C., as shown in FIG. 7, the sample was rotated so that a magnetic field was applied in a direction B perpendicular to the direction A in FIG. 6, and the sample was further cooled to 50 ° C. in this state. . By rotating the sample, the direction 11a of the magnetic anisotropy of the antiferromagnetic layer 11 at about the magnetic instability temperature
Were aligned in the direction B, which is the direction in which the external magnetic field was applied. In the laminated film obtained as described above, the first ferromagnetic layer 12
And the first antiferromagnetic layer 11 are magnetically coupled, and the direction of the magnetic anisotropy of the first ferromagnetic layer 12 is the same as the direction 11a of the magnetic anisotropy of the first antiferromagnetic layer 11. Become. Similarly, the second
The direction of the magnetic anisotropy of the ferromagnetic layer 14 is also the same as the direction 15a of the magnetic anisotropy of the second antiferromagnetic layer 15.

As described above, the direction of the magnetic anisotropy in the first ferromagnetic layer and the direction of the magnetic anisotropy in the second ferromagnetic layer make an angle of about 90 °, ie, almost 90 °. A perpendicular magnetoresistance effect film was obtained.

A sample of the obtained magnetoresistive film was 3 μm thick.
8, the electrodes 19a and 19b are provided at both ends of the magnetoresistive film 10, as shown in FIG.
Was formed. A current of 6 mA was passed in the longitudinal direction of the device, and the magnetic field dependence of the device resistance was measured. Here, the direction A shown in FIG. 6 was set as the element longitudinal direction, and the detection magnetic field was applied in the direction B shown in FIG. The measurement was performed using a DC four-terminal method.

FIG. 9 is a VH characteristic diagram showing the magnetic field dependence of the element resistance obtained as described above. The magnetic field was applied at ± 250 Oe. As is apparent from FIG.
No discontinuity is observed in the output curve of the H characteristic.

For comparison, a magnetoresistive film having a laminated structure shown in FIG. 10 was prepared, and the VH characteristics were evaluated in the same manner. In the laminated film 20 shown in FIG. 10, a base film 27, a second ferromagnetic layer 24, a nonmagnetic conductive layer 2
3, a first ferromagnetic layer 22, a first antiferromagnetic layer 21, and a protective film 26 are sequentially laminated. In the laminated structure of the first embodiment shown in FIG. Are omitted. In the magnetoresistive film of this comparative example, the application of the magnetic field to the antiferromagnetic layer was performed in the same manner as in Example 1. The magnetic field applied at the time of measuring the VH characteristics was set to ± 150 Oe.

As shown in FIG. 11, in the magnetoresistive film of the comparative example shown in FIG. 10, a discontinuity (shown by an arrow) is clearly observed in the output curve, and Barkhausen noise is generated.

[0045]Example 2 A magnetoresistive film having a laminated structure shown in FIG.
Was. On a substrate 38 which is a silicon substrate, a base film 37,
The second antiferromagnetic layer 35, the second ferromagnetic layer 34,
Electric layer 33, first ferromagnetic layer 32, first antiferromagnetic layer 3
1 and a protective film 36 are stacked. In this example
The second anti-ferromagnetic property of the magnetoresistive film 10 shown in FIG.
Ni of the conductive layer 15₅₀Mn₅₀Instead of a layer (5 nm thick)
Ir₂₀Mn ₈₀Except that a layer (5 nm thick) was used.
It has a structure similar to that of the first embodiment. In this embodiment,
The first antiferromagnetic layer 31 and the second antiferromagnetic layer 35
And the same material Ir₂₀Mn₈₀Is used.
Only the thickness of the film is changed. In the present embodiment,
Using the same material as the antiferromagnetic material used for the ferromagnetic layer,
Magnetic instability of each antiferromagnetic layer by changing the film thickness
The temperature is changing.

Also in this embodiment, the direction of the magnetic anisotropy is set by applying a magnetic field to the first antiferromagnetic layer and the second antiferromagnetic layer in the same manner as in the first embodiment. can do. That is, the magnetic anisotropy of the first antiferromagnetic layer 31 is set in the direction B shown in FIG. 7 and the magnetic anisotropy of the second antiferromagnetic layer 35 is set in the direction A shown in FIG. Can be. In the magnetoresistive film of this example, as in the magnetoresistive film of Example 1, no discontinuity was observed in the output curve of the VH characteristic.

Example 3 A magnetoresistive film 40 having a laminated structure shown in FIG. 13 was produced. The magnetoresistive film 40 shown in FIG. 13 is different from the magnetoresistive film 10 shown in FIG. 5 in that the second antiferromagnetic layer 15 is replaced with a NiO layer (film thickness: 20 nm) which is an oxide antiferromagnetic material. Have the same laminated structure. As shown in FIG. 13, a magnetoresistive film 40 is formed on a substrate 48, which is a silicon substrate, by forming a base film 47 and a second antiferromagnetic layer 4 on the substrate 48.
5, a second ferromagnetic layer 44, a nonmagnetic conductive layer 43, a first ferromagnetic layer 42, a first antiferromagnetic layer 41, and a protective film 46.

With the laminated structure of this embodiment, the current flowing in the second antiferromagnetic layer 45 made of the oxide antiferromagnetic material can be reduced, and the nonmagnetic conductive layer 43 Current can be concentrated near the interface between the first ferromagnetic layer 42 and the second ferromagnetic layer 44, and higher detection sensitivity can be obtained.

In this embodiment, 1 kO in the direction A shown in FIG.
After applying a magnetic field of e and performing heat treatment at 230 ° C. for 1 hour, when the sample temperature becomes 150 ° C. or less, the sample is heated to 9 ° C.
By rotating by 0 ° and applying a magnetic field in the B direction as shown in FIG. 7, the direction of the magnetic anisotropy of the first antiferromagnetic layer 41 is changed to the B direction shown in FIG. The direction of the magnetic anisotropy of the magnetic layer 45 can be the direction A shown in FIG.

The magnetoresistive film of the third embodiment obtained as described above also has a VH like the magnetoresistive film of the first embodiment.
No discontinuity was observed in the output curve of the characteristic. In each of the above embodiments, the detection magnetic field is applied in the direction of the magnetic anisotropy of the first antiferromagnetic layer and the first ferromagnetic layer. However, the present invention is not limited to this. Instead, the direction in which the detection magnetic field is applied may be substantially the same as the direction of the magnetization anisotropy of the second ferromagnetic layer and the second antiferromagnetic layer.

In each of the above embodiments, the magnetic field is applied by changing the heat treatment temperature after the formation of the laminated film, and the directions of the magnetic anisotropy of the first and second antiferromagnetic layers are made different. However, as described above, in the thin film forming process of the first antiferromagnetic layer and the second antiferromagnetic layer, the directions of the magnetic anisotropy are made different by applying magnetic fields in different directions. You may.

[0052]

According to the present invention, generation of Barkhausen noise can be suppressed without providing a magnetic domain control layer inside the surface of the magnetoresistive film, and miniaturization of the magnetoresistive device can be achieved. can do.

According to the manufacturing method of the present invention, the magnetoresistive film of the present invention can be manufactured efficiently.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a magnetoresistive film according to an embodiment of the present invention.

FIG. 2 is a perspective view of the magnetoresistive film shown in FIG.

FIG. 3 is a diagram illustrating a blocking temperature of an antiferromagnetic material.

FIG. 4 is a diagram showing a relationship between a blocking temperature and a film thickness of an antiferromagnetic layer.

FIG. 5 is a sectional view showing a magnetoresistive effect film of Example 1 according to the present invention.

FIG. 6 is a plan view for explaining a first magnetic field applying step in the manufacturing process of the present invention.

FIG. 7 is a plan view for explaining a second magnetic field application step in the manufacturing process of the present invention.

FIG. 8 is a plan view showing the structure of a magnetoresistive element using the magnetoresistive film of Example 1 of the present invention.

FIG. 9 is a diagram showing VH characteristics of the magnetoresistive film of Example 1 of the present invention.

FIG. 10 is a sectional view showing a magnetoresistive film of a comparative example.

FIG. 11 is a diagram showing VH characteristics of a magnetoresistive film of a comparative example.

FIG. 12 is a sectional view showing a magnetoresistive film according to a second embodiment of the present invention.

FIG. 13 is a sectional view showing a magnetoresistive film according to a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 1st antiferromagnetic layer 2 ... 1st ferromagnetic layer 2a ... The direction of magnetic anisotropy of a 1st ferromagnetic layer and a 1st antiferromagnetic layer 3 ... Nonmagnetic conductive layer 4 ... 2nd 4a: direction of magnetic anisotropy of the second ferromagnetic layer and the second antiferromagnetic layer 5: second antiferromagnetic layer 6: direction of external magnetic field 10, 30, 40 ... magnetoresistance Effect film 11, 31, 41: First antiferromagnetic layer 12, 32, 42 First ferromagnetic layer 13, 33, 43 Nonmagnetic conductive layer 14, 34, 44 Second ferromagnetic layer 15 , 35, 45 ... second antiferromagnetic layer 16, 36, 46 ... protective film 17, 37, 47 ... base film 18, 38, 48 ... substrate

Claims (8)

[Claims] 1. A magnetoresistive film for detecting a change in an external magnetic field by a change in magnetoresistance, comprising: a nonmagnetic conductive layer; a first ferromagnetic layer provided between said nonmagnetic conductive layers; 2 ferromagnetic layers, a first antiferromagnetic layer magnetically coupled to the first ferromagnetic layer, and a second antiferromagnetic layer magnetically coupled to the second ferromagnetic layer. The direction of the magnetic anisotropy of the first ferromagnetic layer and the first antiferromagnetic layer is substantially the same as the direction of the magnetic anisotropy of the second ferromagnetic layer and the second antiferromagnetic layer. A magnetoresistive effect film characterized in that: 2. The direction of an easy axis of magnetization of the first ferromagnetic layer induced by magnetic coupling with the first antiferromagnetic layer is aligned with the direction of the external magnetic field, and 2. The magnetoresistive film according to claim 1, wherein the direction of the hard axis of the second ferromagnetic layer induced by magnetic coupling with the ferromagnetic layer is aligned with the direction of the external magnetic field. 3. The magnetoresistive element according to claim 1, wherein the direction of the easy axis of the first ferromagnetic layer is substantially orthogonal to the direction of the easy axis of the second ferromagnetic layer. Effect membrane. 4. The method according to claim 1, wherein at least one of said first antiferromagnetic layer and said second antiferromagnetic layer is formed of an oxide antiferromagnetic material. Item 2. The magnetoresistive film according to item 1. 5. The magnetoresistive device according to claim 1, wherein said first antiferromagnetic layer and said second antiferromagnetic layer are formed of different antiferromagnetic materials. Effect membrane. 6. The method according to claim 1, wherein the first antiferromagnetic layer and the second antiferromagnetic layer have different thicknesses.
Item 7. The magnetoresistive effect film according to item 1. 7. The method of manufacturing a magnetoresistive film according to claim 1, wherein the nonmagnetic conductive layer, the first and second ferromagnetic layers, and the Forming a laminated film having first and second antiferromagnetic layers; and heating the laminated film to a first predetermined temperature and applying a magnetic field to the first ferromagnetic layer and the first ferromagnetic layer. A first magnetic field for aligning the direction of the magnetic anisotropy of the antiferromagnetic layer of the second layer with the direction of the magnetic anisotropy of the second ferromagnetic layer and the second antiferromagnetic layer in substantially the same direction; Applying the first ferromagnetic layer by setting the laminated film to a second predetermined temperature lower than the first predetermined temperature and applying a magnetic field in a direction different from that of the first magnetic field applying step. And the first
The direction of the magnetic anisotropy of either the direction of the magnetic anisotropy of the antiferromagnetic layer or the direction of the magnetic anisotropy of the second ferromagnetic layer and the direction of the magnetic anisotropy of the second antiferromagnetic layer is different from each other. A second magnetic field application step of aligning in a magnetic field application direction. 8. The method of manufacturing a magnetoresistive film according to claim 1, wherein the step of forming the first antiferromagnetic layer and the step of forming the second antiferromagnetic layer are performed. In the step of forming a layer, the first antiferromagnetic layer and the second antiferromagnetic layer having magnetic anisotropy in directions different from each other are formed by applying respective magnetic fields in directions different from each other. A method for manufacturing a magnetoresistive film, comprising forming an antiferromagnetic layer according to (1).