JP2002230717A - Gmr head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the sensitivity of a reproducing head for enhancing recording density of a spin valve type GMR head. SOLUTION: In the GMR head constituted of a spin valve type reproducing head having a fixed layer 20 formed by laminating an anti-ferromagnetic body 21 and a ferromagnetic body 22, a separation layer 30 on the fixed layer and a free layer 40 consisting of a ferromagnetic body on the separation layer and an electromagnetic induction type recording head, a body-centered cubic crystal NiFeCr layer 10 is formed on a substrate 80 and the fixed layer 20 is formed on the body-centered cubic crystal NiFeCr layer. If the composition of the body-centered cubic crystal NiFeCr layer 10 as a base layer is expressed by (Ni1-xFex)1-yCry, 0<x<1, and 0.32<y<0.38 are satisfied in the GMR head. The MR ratio can be increased by 30-40% by using a body-centered cubic crystal NiFeCr film as a base to constitute a spin valve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a giant magnetoresistive (GMR) head, and more particularly to a spin valve type GMR head applied to a magnetic recording apparatus, which has a high reproduction sensitivity.

[0002]

2. Description of the Related Art To increase the sensitivity of a spin valve, a method of reducing the physical film thickness of a fixed layer, a separation layer, and a free layer to increase the resistance change amount, and installing an oxide layer in the fixed layer or at the interface of the free layer. , A method of increasing the resistance change amount by suppressing interface scattering,
A method has been proposed in which a material having a low specific resistance is brought into contact with and laminated on the free layer to increase the resistance change rate.

The thickness of the pinned layer is the largest, and the present limit is about 10 nm in PtMn among antiferromagnetic materials having preferable temperature characteristics, and there is a limit. The provision of an oxide layer on the fixed layer is effective in increasing the amount of change in magnetoresistance, but may reduce the exchange coupling between the antiferromagnetic material and the ferromagnetic material, thereby making the operation in the magnetic disk device unstable. It is necessary to balance the increase in the resistance change amount. Installing a low-resistance film on the free layer is effective for increasing the magnetoresistance ratio (MR ratio).
The improvement is about 10%.

Further, PtMn, which is widely used at present, is
Is that sufficient exchange coupling occurs in the fixed layer irrespective of the presence or absence of the underlying alignment film, that is, the crystal orientation of PtMn itself. Therefore, when the NiFe / Ta constituent layer is applied to the underlying layer, the overall specific resistance decreases. There is an effect that the element resistance does not change even if the sensitivity of the magneto-sensitive portion MR is reduced and the height is reduced. FIG. 6 shows a conventional structure that does not use the method of increasing sensitivity. The MR ratio of the spin valve having this configuration is 7%.

[0005] An embodiment of a film configuration incorporating all of the high sensitivity techniques will be described below. A unit thickness of nm is shown on a glass substrate (shown below, for example, 1 in 15 PtMn).
5) A spin valve having the following structure was formed. Glass / 1
Ta / 2NiFe / 15PtMn / 1.5CoFe /
0.8Ru / 1.5CoFe / oxidation treatment / 2CoFe /
2.1Cu / 0.5CoFe / 3NiFe / 0.6Cu
A spin valve is formed with a configuration of / 2Ta,
Heat treatment in magnetic field for hours. As a result, an MR ratio of 10% and a fixed layer coupling magnetic field of 63.2 × 10 ³ A / m (800 Oe) were obtained.

Further, glass / 1 Ta /
2NiFe / 15PtMn / 1.5CoFe / 0.8R
u / 2CoFe / 2.1Cu / 0.5CoFe / 3Ni
The spin valve having the Fe / 0.6Cu / 2Ta structure has an MR ratio of 8 to 9% and a fixed layer coupling magnetic field of 118.5 × 10 ³ A / m.
(1,500 Oe).

As another technique for improving the sensitivity, since the conduction phenomenon in the thin film depends on the crystal grain size, a technique of increasing the crystal grain size and increasing the anisotropic magnetoresistance effect (AMR) has been proposed. II Transaction on Magnetics, Vol. 36, No. 1, p. 381 (January 2000,
IEEE. Trans. MAG-36, vol. 1, p
381, 2000) (known example 1).

In the above-mentioned known example 1, NiFeCr is used as a base film, Ni0.81Fe0.19 is laminated, the AMR effect is measured, and the MR ratio becomes maximum when the Cr content is around 40 atomic%.
It is shown that there is no effect at 5 atomic% or less and 55 atomic% or more. On the other hand, by the same author, JAAP, Vol. 87, No. 9, pp. 6992 (January 2000, JA
P87 vol 9, p 6992, 2000) discloses that the MR ratio becomes maximum at around 44 atomic% (known example 2). However, since these are AMR effects, the MR ratio is at most 3.5%, which is extremely smaller than the GMR effect.

[0009] Further, in the known example 1, a base N having a high MR ratio is provided.
iFeCr is a body-centered cubic lattice with many defects, and is transformed into a face-centered cubic lattice by stacking NiFe of the face-centered cubic lattice on top of this, so that the crystal grains of NiFe are coarsened.
It is described that it is important for NiFeCr not to align the orientation.

A disclosure of a spin valve film based on NiFeCr is disclosed in Japanese Patent Application Laid-Open No. 2000-57535 (known example 3). Known example 3 is Cr25
Atomic% of NiFeCr is arranged between the Ta base and MnPt or the free layer to control the orientation.

The present inventors have studied and found that the above-mentioned NiFeCr
It has been found that / Ta is almost the same effect as the above-mentioned NiFe / Ta, and has an effect that the MR ratio does not decrease even if the thickness of NiFeCr is increased to 20 to 70 nm. Further, in the above-mentioned known example 3, the relationship between the Cr composition and the amount of change in magnetoresistance is not clear.

[0012]

In the field of magnetic recording, such as a magnetic disk drive or a magnetic tape drive, in which the GMR head of the present invention is used, it is always required to increase the capacity and reduce the size of the magnetic recording device. In order to realize the above, there is a problem that the recording density is constantly increased.

FIG. 4 shows an outline of a magnetic disk drive. The apparatus includes a magnetic disk as a recording medium, a rotary motor, a magnetic head attached to the tip of an arm, an arm driving unit, and an electric system. The increase in the recording density is due to the reduction in the recording width and the shortest recording wavelength, but this leads to a decrease in the reproduction output of the magnetic head, and therefore the giant magnetoresistive (GMR) type.
The head has been proposed as a spin valve structure and has become the current mainstream technology.

Conventionally, a spin valve head mainly comprises three elements: a fixed layer, a separation layer, and a free layer. The fixed layer is FeM
An antiferromagnetic material such as n, NiO, CrMnPt, PtMn, PtMnRh and a ferromagnetic material such as Co and CoFe are mainly laminated. The separation layer is mainly made of Cu or the like, and the free layer is made of Co, C
It is composed of oFe or laminated with NiFe.

The order of lamination of the fixed layer, the separation layer, and the free layer is selected depending on the type of the antiferromagnetic film, the structure design of the spin valve head, and the like. PtMn can have any configuration. The spin valve head is required to have a reduced dimension in the MR height direction 120 (see FIG. 5) for higher sensitivity. To reduce the distortion of the reproduced signal accompanying this, the fixed layer is made of an antiferromagnetic material. Mainly Co / Ru / Co or CoFe
/ Ru / CoFe ferromagnetic material such as a laminated structure (the laminated structure functions as a ferromagnetic layer as a whole), and a laminated ferrimagnetic structure that substantially reduces the magnetization of the fixed layer. good.

The free layer is made of Co for improving the reproduction sensitivity.
Alternatively, CoFe is disposed at the interface of the separation layer, and NiFe is laminated. In order to further improve the sensitivity, a case where Co or CoFe is used alone or a stacked ferrimagnetic structure using these ferromagnetic materials and Ru may be used.

It is also effective to use a double spin valve structure in which the fixed layer has two upper and lower layers and the free layer is located at the center.

However, these techniques achieve high sensitivity on the premise that the spin valve magneto-sensitive portion is reduced in the MR height direction, and the recent value of about 0.2 μm (micrometer) is determined by machining. It is approaching the processing limit. With the conventional technology, a significant improvement in the MR ratio cannot be expected.
There was a problem in realizing a highly sensitive GMR head.

[0019]

In order to solve the above problems, the present invention mainly employs the following configuration. A spin-valve reproducing head for forming a fixed layer in which an antiferromagnetic material and a ferromagnetic material are stacked, a separation layer on the fixed layer, and a free layer of the ferromagnetic material on the separation layer; A GMR head comprising: a body-centered cubic NiFeCr layer formed on a substrate; and the fixed layer formed on the body-centered cubic NiFeCr layer.

In the GMR head, the composition of the body-centered cubic NiFeCr layer is (Ni1-xFe
x) When expressed as 1-yCry, 0 <x <1 and 0.
A GMR head in which 32 <y <0.38.

A spin-valve reproducing head for forming a fixed layer in which an antiferromagnetic material and a ferromagnetic material are stacked, a separation layer on the fixed layer, and a free layer of the ferromagnetic material on the separation layer; GMR comprising: an electromagnetic induction type recording head
A GMR head comprising: a body-centered cubic NiFeCr layer and an auxiliary layer formed on a substrate; and the fixed layer formed on the auxiliary layer.

A spin-valve reproducing head for forming a free layer made of a ferromagnetic material, a separating layer on the free layer, and a fixed layer on which a ferromagnetic material and an antiferromagnetic material are laminated on the separating layer; GMR comprising: an electromagnetic induction type recording head
A GMR head comprising: a body-centered cubic NiFeCr layer formed on a substrate; and the free layer formed on the body-centered cubic NiFeCr layer.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A high-sensitivity GMR head according to an embodiment of the present invention will be described below with reference to the drawings. 1, 2 and 3 show examples of the configuration of a spin valve head according to a basic embodiment of the present invention.

First, an outline of a characteristic configuration, function or operation of the present invention will be described. That is, the constitutional feature of the present invention is that a main component of a spin valve film formed of a fixed layer made of an antiferromagnetic material and a ferromagnetic material, a free layer, and a separation layer between the fixed layer and the free layer. NiFe
A Cr-only film.
It has been newly found that there is a special effect in setting the composition of the Cr-only film in a specific range.

As a first configuration example, a spin-valve film having a configuration incorporating a conventional method of increasing sensitivity is used.
Using iFeCr as a base film, changing the Cr composition and
FIG. 7 shows the result of examining the ratio (the rate of change in magnetoresistance, which is the ratio of the rate of change of resistance when a magnetic field is applied divided by the resistance value). The film configuration is as shown in FIG. 7, and NiFeCr is interposed between the glass substrate and PtMn. In the experiment, RF magnetron sputtering was used, and the composition was changed by placing a Cr chip on a Ni0.82Fe0.18 target and changing the number of chips.

As shown in FIG. 7, when the Cr composition is increased from about 30 atomic%, the MR ratio increases, and
It becomes the maximum at 37 atomic%. When it exceeds 38 atomic%, the MR ratio sharply decreases, and when the composition is more than 38 atomic%, the MR ratio becomes about 6%, which is lower than that when the base film is Ta.
Therefore, the spin valve having this film configuration has a Cr content of 32 to 3 times.
Up to 8 atomic% is effective because the MR ratio becomes 10% or more. In addition, the fixed layer CoFe of this configuration example is
/Oxidation/2.0 nm CoFe
Even with the Fe single layer, the MR ratio did not change as a result of the experiment, and the operation as the spin valve head was the same.

Next, as a second configuration example, a NiFe layer is placed between NiFeCr and PtMn as base films,
FIG. 8 shows the results of experiments in which the Cr composition of iFeCr was changed. The film configuration is as described in FIG. As shown in FIG. 8, when the Cr composition increases from 30 atomic%, the first
As in the configuration example, the MR ratio increases.

A high MR ratio is as wide as 34 to 37 atomic%. Further, even if the atomic ratio exceeds 40 atomic%, the decrease in the MR ratio is gradual, and the MR ratio is maintained at 9% up to 50 atomic%. MR
The ratio of 10% or more is 32 to 42 atomic%. Further, similarly to the first configuration example, the fixed layer CoFe is
As CoFe / oxidized / 2.0 nm CoFe, 2.0
The MR ratio did not change even with the nmCoFe single layer, and the operation as the spin valve head was the same.

Next, as a third configuration example, NiFeCr
FIG. 9 shows the results of an experiment in which the Cr composition in NiFeCr of a spin valve in which PtMn was provided on the upper portion and the free layer was provided on the lower portion was used as a base film. As shown in FIG. 9, a base film of NiFeCr is interposed between glass of the substrate and NiFe of the free layer. Here, the MR ratio shows the same Cr composition dependency as in FIG. This third configuration example is described with reference to FIGS.
Unlike the two structures shown in the above, since it is not oxidized,
An MR ratio of 8% or more is an effective range. Effective Cr
The composition will be 32-42 atomic%. Also in this configuration example, no sharp decrease in the MR ratio due to the increase or decrease in the Cr amount is observed.

The above configuration example is different from the known examples 1 and 2 in terms of the base of the spin valve, and the composition range is also 40 atomic% center found in the known example 1 or 40 to 53% in the known example 2. % Range clearly, and it is considered that a phenomenon different from the crystal grain coarsening effect due to the lattice transformation shown in Known Example 1 is acting.

FIG. 10 shows a base film (Ni0.82F).
e0.18) A wide-angle X-ray diffraction pattern A and an in-plane X-ray diffraction pattern B of a 65Cr35 single layer film of 5 nm are shown. In FIG. 10, the sample rotation angles are shown as θ and Φ, respectively (the detector rotation angles are 2θ and 2Φ). From the wide-angle X-ray diffraction pattern A (the orientation of the underlayer film, which is the sample surface, in the direction perpendicular to the surface), which is the result of diffraction in the direction perpendicular to the film surface, it can be seen that NiFeCr is crystal-oriented perpendicular to the film surface. However, since it is a single peak, the crystal structure cannot be identified.

Therefore, the in-plane X-ray diffraction shown in the lower part of FIG. 10 was performed to examine the crystal structure in the film plane. From the pattern B, it can be seen that the film is a body-centered cubic lattice and is oriented (011) perpendicular to the film surface, since there are diffraction lines at almost the same position as in A and around 75 °. This is known from NiFe
The structure is different from that of the Cr film (which is not a deflected body-centered cubic lattice), and the difference depending on the composition range is obvious.

Further, a T of 5 to 20 A is placed under NiFeCr.
a and the atomic% of the Cr content of NiFeCr
Is 35 to 38 (common to the composition range of the present invention), the exchange coupling between PtMn and CoFe is significantly reduced,
The spin valve could not be evaluated. This is different from known example 3.

[First Embodiment] In the first embodiment of the present invention shown in FIG. 1, a NiFeCr film is formed as a base layer 10 on a substrate 80 to a thickness of 3 to 6 nm. Next, the antiferromagnetic material (PtMn) 21 is continuously applied under vacuum to 10 to 15 n.
m, a ferromagnetic material (CoFe) 22 is formed to a thickness of 2 nm, Ru is formed to 6 to 8 A and CoFe is formed to 2 to 3 A according to design to form a fixed layer 20, and further, a Cu film is formed continuously as a separation film 30.
nm, as the free layer 40, a total of 2
After the formation of ４4 nm, the protection layer 50 is formed to a total thickness of 3 nm with Cu and Ta.

Thereafter, the permanent magnet layer 60, the electrode layer 70, and the protective film 90 were formed by a method known as a hard bias process to obtain a spin valve head. As an underlayer, the conventional NiFe / Ta has a M of about 7% in the related art.
The R ratio was greatly improved to 10%, and the reproduction output was improved by 40%.

[Second Embodiment] In the first embodiment, by setting the Cr content of NiFeCr to a composition range of 32 to 38 atomic%, a unique effect exceeding the conventional example as shown in FIG. 7 is obtained. Played. At this time, the ratio of Ni and Fe is
The effect does not change in a wide range of １1.

[Third Embodiment] In the third embodiment of the present invention shown in FIG. 2, a NiFeCr film is formed as a base layer 10 on a substrate 80 to a thickness of 2 to 5 nm (compared to the first embodiment, The thickness is reduced by the thickness of the auxiliary layer shown in FIG. Subsequently, NiFe is used as the auxiliary layer 15 for 1 to 3 n.
m. Then the antiferromagnetic material (Pt
Mn) 21 to 10 to 15 nm, ferromagnetic substance (CoFe) 2
2 is formed to a thickness of 2 nm, and Ru is set to 6 to 8 A and Co
2 to 3 A (Angstrom) of Fe to form fixed layer 2
0, and 2 nm of Cu as the separation film 30 continuously.
2-4n of CoFe and NiFe as the free layer 40
After the formation of the protective layer 50, the total thickness of Cu and Ta is 3n.
m.

Thereafter, by a hard bias process,
The permanent magnet layer 60, the electrode layer 70, and the protective film 90 were formed to obtain a spin valve head. As the underlayer, Ni shown in FIG.
The MR ratio of about 7% of Fe / Ta was improved to 10%, and the reproduction output was improved by 40%. Further, N from the first embodiment
There is an effect that iFeCr can be made thin.

"Fourth Embodiment" In the third embodiment, by setting the Cr content of NiFeCr to a composition range of 32 to 42 atomic%, a unique effect exceeding the conventional example as shown in FIG. 8 can be obtained. Played. At this time, the ratio of Ni and Fe is
The effect does not change in a wide range of １1. Here, the auxiliary layer 1
By adopting No. 5, the composition range of the Cr content is 32 to 3
8 to 32 to 42 atomic%.

The auxiliary layer is made of Co, CoF in addition to NiFe.
e, CoNiFe, etc., may be a face-centered cubic or close-packed hexagonal material.

[Fifth Embodiment] In a fifth embodiment of the present invention shown in FIG. 3, NiFeCr is formed as a base layer 10 on a substrate 80 to a thickness of 3 to 7 nm, and the free layer 40 is continuously formed under vacuum. , A NiFe film and a CoFe film are formed in a total thickness of 4 nm.
Is formed on the ferromagnetic body 22 by forming CoFe2 to 3 nm, Ru is formed by 6 to 8 A and CoFe is formed by 2 A, and PtMn is formed on the antiferromagnetic body 21 by 15 nm to form the fixed layer 20. Was formed to a thickness of 2 nm, and a spin valve head was formed by a hard bias process. When Ta2 nm was used for the base film, the MR ratio was 8%, which was 8%.
With eCr, it is improved by about 10% and about 20%.

[Sixth Embodiment] In the fifth embodiment of the present invention shown in FIG.
By setting the composition range to 42 at%, a unique effect exceeding the conventional example as shown in FIG. 9 was obtained. At this time, Ni, Fe
The effect does not change over a wide range of Fe from 0 to 1.

Seventh Embodiment In the fifth embodiment, the buffer layer is provided between NiFeCr of the underlayer and NiFe and / or CoFe of the free layer to reduce the magnetostriction constant of the free layer. It can also be adjusted. For example, between NiFe and the underlayer, Pd is used as a buffer layer.
When the thickness is set to 6 A (angstrom), the magnetostriction constant of the free layer can be reduced to 1 × 10 −6 to 1 × 10 −7. Further, when Pd is thickened, the magnetostriction becomes negative. The same magnetostriction adjusting effect is obtained by replacing Pd with Pt, Ru, Rh, I
r, Re, Os, Cu, Ag, Au or an alloy thereof can also be obtained.

In the structure of the spin valve film described above, the fixed layer is described as a laminate of an antiferromagnetic layer and a ferromagnetic layer (single layer or multilayer) as shown in FIG. As shown in FIG. 7, the ferromagnetic material of CoFe
It has a laminated ferri structure that functions as a ferrimagnetic material (a kind of antiferromagnetic material) by being laminated with u interposed therebetween.
Here, when the film thickness of each CoFe is set to 1: 1, the laminated ferrimagnetic structure shows an attribute of an antiferromagnetic material, and when the film thickness is not 1: 1 but has a difference in film thickness, the ferrimagnetic material becomes substantially ferrimagnetic. Any of the laminated ferrimagnetic structures can function as a fixed layer in combination with the antiferromagnetic material.

The free layer shown in FIG. 1 may be a single layer or a multilayer of a ferromagnetic material.
A stacked structure may be adopted in which the ferromagnetic materials of iFe are stacked with Ru interposed and the thickness of each ferromagnetic material is made different to function as a substantial ferrimagnetic material.

Incidentally, the laminated ferri structure generally refers to a configuration in which two laminated ferromagnetic layers are antiferromagnetically coupled by using an intermediate film to reduce a substantial magnetic moment. The ferromagnetic layer may be made of any of Co, CoFe, NiFe and alloys thereof, and the intermediate film is made of I, in addition to Ru.
r, Rh, Cr, Cu may be used. When used for a spin valve film, CoFe / Ru / Co
Fe / PtMn or the like is referred to as a laminated ferri-fixed layer. When used as a free layer, CoFe / NiFe / Ru / Ni
The structure of Fe or the like is referred to as a laminated ferri-free layer.

Further, the spin valve film according to the embodiment of the present invention has been described with reference to the main constituent layer including the antiferromagnetic material, the ferromagnetic material, the separation layer, and the free layer as shown in FIG. 1, but is not limited thereto. , Antiferromagnetic material, ferromagnetic material, separation layer, free layer, C
The dual spin valve film forming the main constituent layer composed of the u layer, the ferromagnetic material, and the antiferromagnetic material can also be an embodiment of the present invention.

[0048]

By using the NiFeCr underlayer of the present invention, it is not necessary to pursue a thin film accompanied by remarkable technical difficulties,
High sensitivity of the spin valve was achieved. As a result, a high recording density GMR head was realized.

NiFeCr is also effective for improving the MR ratio as a base for a double spin valve and a base for a tunnel type GMR head.

The NiFeCr underlayer prevents the coercive force of the hard bias film from decreasing at the overlapping portion (referred to as an abutment portion) with the MR film, stabilizes the magnetization direction of the MR film, and reduces Barkhausen noise. effective.

When NiFeCr is used as a base material of the medium, it has the effect of reducing the noise without lowering the coercive force as compared with Cr or the like.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a spin valve head according to first and second embodiments of the present invention.

FIG. 2 is a diagram showing a configuration example of a spin valve head according to third and fourth embodiments of the present invention.

FIG. 3 is a diagram showing a configuration example of a spin valve head according to fifth to seventh embodiments of the present invention.

FIG. 4 is a diagram showing a schematic configuration of a magnetic disk device.

FIG. 5 is a configuration diagram of a spin valve unit in the GMR head.

FIG. 6 is a diagram showing a configuration of an MR film of a spin valve head having a conventional structure.

FIG. 7 shows the MR ratio and Cr in the first and second embodiments.
FIG. 3 is a diagram showing the relationship between compositions.

FIG. 8 shows the MR ratio and Cr in the third and fourth embodiments.
FIG. 3 is a diagram showing the relationship between compositions.

FIG. 9 is a diagram showing the relationship between the MR ratio and the Cr composition in the fifth to seventh embodiments.

FIG. 10 is a diagram showing an X-ray diffraction analysis result of a NiFeCr film structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Underlayer 15 Auxiliary layer 20 Spin valve pinned layer 21 Antiferromagnetic film 22 Ferromagnetic film 30 Separation layer 40 Free layer 50 Protective layer 60 Permanent magnet layer 70 Electrode 100 Shield layer 1 110 Reproducing head track width 120 MR height 130, 140 Gap film 150 Shield 2 201 Base 202 Spindle 203 Magnetic disk 204 Magnetic head 205 Suspension

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 43/08 G01R 33/06 R (72) Inventor Tatsumi Hirano 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture No. Hitachi, Ltd.Hitachi Laboratory (72) Inventor Hiroyuki Hoshiya 1-280 Higashi-Koigabo, Kokubunji-shi, Tokyo F-term in Central Research Laboratory, Hitachi, Ltd. 2G017 AA01 AB07 AD54 AD65 5D034 BA04 BA05 BA12 BA16 BA21 BB12 CA08 5E049 AA07 AA09 AC05 BA12 CB02

Claims (10)

[Claims] 1. A spin-valve reproducing head for forming a fixed layer in which an antiferromagnetic material and a ferromagnetic material are stacked, a separation layer on the fixed layer, and a free layer made of a ferromagnetic material on the separation layer. A GMR head, comprising: a body-centered cubic NiFeCr layer formed on a substrate; and the fixed layer formed on the body-centered cubic NiFeCr layer. GMR head. 2. The GMR head according to claim 1, wherein the composition of the body-centered cubic NiFeCr layer is (Ni1-x
Fex) 1-yCry, where 0 <x <1 and 0.32 <y <0.38.
R head. 3. A spin-valve read head for forming a fixed layer in which an antiferromagnetic material and a ferromagnetic material are stacked, a separation layer on the fixed layer, and a free layer of the ferromagnetic material on the separation layer. A GMR head comprising: a body-centered cubic NiFeCr layer and an auxiliary layer on a substrate;
A GMR head, wherein the fixed layer is formed on the auxiliary layer. 4. The GMR head according to claim 3, wherein the auxiliary layer is a face-centered cubic or hexagonal material, and the composition of the body-centered cubic NiFeCr layer is (Ni1-x
Fex) 1-yCry, where 0 <x <1 and 0.32 <y <0.42.
R head. 5. A spin-valve reproducing head for forming a free layer made of a ferromagnetic material, a separation layer on the free layer, and a fixed layer on which a ferromagnetic material and an antiferromagnetic material are stacked on the separation layer. A GMR head comprising: a body-centered cubic NiFeCr layer formed on a substrate; and the free layer formed on the body-centered cubic NiFeCr layer. GMR head. 6. The GMR head according to claim 5, wherein the composition of the body-centered cubic NiFeCr layer is (Ni1-x
Fex) 1-yCry, where 0 <x <1 and 0.32 <y <0.42.
R head. 7. The GMR head according to claim 5, wherein a buffer layer is formed between the body-centered cubic NiFeCr layer and the free layer, and the buffer layer is formed of Pd, Pt, Ru, and Rh. , Ir, Re,
A GMR head comprising Os, Cu, Ag, Au or an alloy thereof. 8. The GMR head according to claim 1, wherein the ferromagnetic material of the fixed layer is formed by laminating a ferromagnetic material, and is substantially a ferrimagnetic material or an antiferromagnetic material. A GMR head, which is a layer functioning as a magnetic material, wherein the free layer is a layer in which a ferromagnetic material is laminated and functions substantially as a ferrimagnetic material. 9. The GMR head according to claim 1, wherein the ferromagnetic material of the fixed layer is formed by laminating a ferromagnetic material, and is substantially a ferrimagnetic material or an antiferromagnetic material. A GMR head, which is a layer functioning as a magnetic material, wherein the fixed layer is a dual spin valve film in which a fixed layer is formed above and below with a non-magnetic material interposed. 10. The GMR head according to claim 9, wherein the free layer is a layer in which a ferromagnetic material is laminated and functions substantially as a ferrimagnetic material.