JP2004221526A - Thin magnetic film and magnetoresistive effect element using the same, and magnetic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic thin film having a large ratio of spin polarization, and a magnetoresistive effect element using the same, and a magnetic device thereof. <P>SOLUTION: The magnetic thin film includes a substrate 2 and a CO<SB>2</SB>Fe<SB>x</SB>Cr<SB>1-x</SB>Al thin film 3, and the CO<SB>2</SB>Fe<SB>x</SB>Cr<SB>1-x</SB>Al thin film 3 has one structure from an L2<SB>1</SB>, B2, and A2 structures, where 0≤x≤1. In a room temperature, the magnetic thin film shows ferromagnetism and can provide the large ratio of the spin polarization. A buffer layer 4 can be disposed between the substrate 2 and the CO<SB>2</SB>Fe<SB>x</SB>Cr<SB>1-x</SB>Al thin film 3. A tunnel magnetoresistive effect element using this magnetic thin film and a giant magnetoresistive effect element can provide large TMR and GMR in a low magnetic field in the room temperature. Furthermore, the magnetic device, a magnetic head, and a magnetic recording device using these magnetoresistive effect elements are provided. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a magnetic thin film having a large spin polarizability, a magnetoresistive element using the same, and a magnetic device.

In recent years, a giant magnetoresistance (GMR) effect element composed of a multilayer film of a ferromagnetic layer / a nonmagnetic metal layer, a tunnel magnetoresistance effect element composed of a ferromagnetic layer / an insulator layer / a ferromagnetic layer, and a ferromagnetic spin tunnel junction ( (MTJ) elements are attracting attention as new magnetic field sensors and nonvolatile random access magnetic memory (MRAM) elements.
The giant magnetoresistive element includes a giant magnetoresistive element having a current in plane (CIP) structure in which a current flows in a film surface and a current perpendicular to the plane (CPP) in which a current flows in a direction perpendicular to the film surface. Giant magnetoresistive elements having a structure are known. The principle of the giant magnetoresistive element is spin-dependent scattering at the interface between the magnetic layer and the nonmagnetic layer. Generally, a giant magnetoresistive element having a CPP structure has a larger GMR than a giant magnetoresistive element having a CIP structure.

  Such a giant magnetoresistive element uses a spin valve type in which an antiferromagnetic layer is brought close to one of the ferromagnetic layers to fix the spin of the ferromagnetic layer. In the case of a spin valve type giant magnetoresistance effect element having a CPP structure, the electric resistivity of the antiferromagnetic layer is about 200 μΩ · cm, which is about two orders of magnitude larger than that of the GMR film. The value of the magnetoresistance of the giant magnetoresistance effect element having the structure is as small as 1% or less. Therefore, although the giant magnetoresistive element having the CIP structure has already been put to practical use in the reproducing head of the hard disk, the giant magnetoresistive effect element having the CPP structure has not been put to practical use yet.

On the other hand, in a tunnel magnetoresistive element or an MTJ, by controlling the magnetization of two ferromagnetic layers to be parallel or antiparallel to each other by an external magnetic field, the magnitudes of tunnel currents in the direction perpendicular to the film surface are different from each other. A resistance (TMR) effect can be obtained at room temperature (see Non-Patent Document 1). This TMR depends on the spin polarizability P at the interface between the ferromagnetic material and the insulator to be used. If the spin polarizabilities of the two ferromagnetic materials are P ₁ and P ₂ , respectively, the TMR is generally given by the following equation (1). Is known to be.

_{TMR = 2P 1 P 2 / (} 1-P 1 P 2) (1)
Here, the spin polarizability P of the ferromagnetic material takes a value of 0 <P ≦ 1.

  Currently, the maximum TMR at room temperature obtained is about 50 percent when using a P-0.5 CoFe alloy.

  At present, the TMR element is expected to be applied to a magnetic head for a hard disk and a nonvolatile random access magnetic memory (MRAM). In the MRAM, the MTJ elements are arranged in a matrix, and a current is applied to a separately provided wiring to apply a magnetic field, thereby controlling two magnetic layers constituting each MTJ element to be parallel and antiparallel to each other. “1” and “0” are recorded. Reading is performed using the TMR effect. However, in the MRAM, when the element size is reduced for higher density, there is a problem that noise accompanying the variation of the elements increases, and the value of TMR is insufficient at present. Therefore, it is necessary to develop an element exhibiting a larger TMR.

As can be seen from the above equation (1), an infinitely large TMR is expected when a magnetic material with P = 1 is used. A magnetic material with P = 1 is called a half metal.
Up to now, band structure calculations have shown that oxides such as Fe ₃ O ₄ , CrO ₂ , (La—Sr) MnO ₃ , Th ₂ MnO ₇ , Sr ₂ FeMoO ₆ , half-Heusler alloys such as NiMnSb, and Co ₂ MnGe, Co ₂ MnSi, such full Heusler alloy having a L2 ₁ structure, such as Co ₂ CrAl is known as a half-metal. For example, it has been reported that a conventional full Heusler alloy having an L2 ₁ structure such as Co ₂ MnGe can be manufactured by heating a substrate to about 200 ° C. and further setting the film thickness to usually 25 nm or more (Non-Patent Document 2). reference).

Recently, Co ₂ Fe _0.4 Cr _0.6 Al was substituted for part of Fe and Cr is a constituent element of Co ₂ CrAl of Hametaru also, according to the theoretical calculation of the band structure, reported to be a L2 ₁ type half-metal (See Non-Patent Document 3). However, the thin film and the tunnel junction have not been manufactured. Therefore, similarly to the conventional L2 ₁ type compound, it is not experimentally known whether or not this thin film shows a half metal characteristic or a large TMR characteristic.

T. Miyazaki and N. Tezuka, "Spin polarized tunneling in ferromagnet / insulator / ferromagnet junctions", 1995, J. Magn. Magn. Mater, L39, p.1231 T. Ambrose, J. J. Crebs and G. A. Prinz, "Magnetic properties of single crystal C2MnGe Heusler alloy films", 2000, Appl. Phys. Lett., Vol. 87, p. 5463 T. Block, C. Felser, and J. Windeln, "Spin Polarized Tunneling at Room Temperature in a Heusler Compound-a non-oxide Materials with a Large Negative Magnetoresistance Effect in Low Magnetic Fields", April 28, 2002, Intermag Digest, EE01

  In the giant magnetoresistive effect element having the CIP structure, which has been practically used in the conventional reproducing head of a hard disk, miniaturization is being promoted for high recording density. However, with the miniaturization of the element, shortage of signal voltage is expected. Therefore, it is required to improve the performance of a giant magnetoresistive element having a CPP structure instead of the giant magnetoresistive element having a CIP structure, but it has not been realized yet.

Except for the above-mentioned half-metal Co ₂ CrAl, a half-metal thin film is manufactured. However, it is necessary to heat the substrate to 300 ° C. or higher, or to heat-treat at 300 ° C. or higher after film formation at room temperature. . However, there is no report that the thin film produced so far is a half metal. Some attempts have been made to fabricate tunnel junction devices using these half-metals, but the TMR at room temperature is unexpectedly small, and at most 10% or less when Fe ₃ O ₄ is used. Met.
As described above, the conventional half-metal thin film requires substrate heating or heat treatment to obtain its structure, and thereby increases the surface roughness or oxidizes. It is considered one.
On the other hand, unlike a bulk material, a thin film may not exhibit half-metal properties on the surface, and the half-metal properties are sensitive to the order of composition and atomic arrangement. The difficulty in obtaining the electronic state of the half-metal is also presumed to be a reason why a large TMR cannot be obtained.
From the above, there is a problem that it is very difficult to actually manufacture a half-metal thin film, and a favorable half-metal thin film that can be used for various magnetoresistive elements has not been obtained.

There is a problem that a Co ₂ CrAl or Co ₂ Fe _0.4 Cr _0.6 Al thin film, which is predicted to be a half metal by theoretical calculation of a band structure, and a tunnel junction using this thin film have not been manufactured.
In general, in a magnetic thin film material, the electronic state of a thin film differs from that of a bulk material, particularly at the surface. For this reason, there is no guarantee that a half metal in a bulk material will be a half metal in a thin film. Furthermore, even if theoretical calculation of the band structure indicates that it is a half metal, there is no guarantee that a half metal is actually obtained in a thin film. It indicates that the above-mentioned various half-metals theoretically shown so far have not been obtained experimentally.
Therefore, as with a conventional full-Heusler alloy L2 ₁ type compound, whether showing a Co ₂ CrAl and Co ₂ Fe _0.4 Cr _0.6 Al thin film is experimentally half metal characteristics and large TMR characteristics is not at all known .

  Conventionally, as described above, there are many materials that have been theoretically pointed out to be half-metals, but none of the prepared thin films exhibit half-metal characteristics at room temperature. Therefore, there is a problem that a large GMR due to a giant magnetoresistive element having a CPP structure at room temperature and a large TMR from an MTJ element cannot be obtained at room temperature, which is expected with a half metal.

  In view of the above problems, an object of the present invention is to provide a magnetic thin film having a large spin polarizability, a magnetoresistive element using the same, and a magnetic device.

The present inventors have produced a Co ₂ F _x Cr _1-x Al (0 ≦ x ≦ 1) thin film, and as a result, this film is ferromagnetic at room temperature and L2 ₁ , B2 without heating the substrate. , A2 structure can be manufactured, and the present invention has been completed.

In order to achieve the above object, a magnetic thin film of the present invention comprises a Co ₂ F _x Cr _1-x Al thin film formed on a substrate, and the Co ₂ F _x Cr _1-x Al thin film comprises L2 ₁ , B2, A2 It has any one of the structures, and 0 ≦ x ≦ 1.
In the above configuration, the Co ₂ F _x Cr _1-x Al thin film can be formed without heating the substrate. The substrate may be any one of thermally oxidized Si, glass, MgO single crystal, GaAs single crystal, and Al ₂ O ₃ single crystal. Further, a buffer layer may be provided between the substrate and the Co ₂ Fe _x Cr _1-x Al thin film. As this buffer layer, at least one of Al, Cu, Cr, Fe, Nb, Ni, Ta, and NiFe can be used.

According to this configuration, a Co ₂ F _x Cr _1-x Al (here, 0 ≦ x ≦ 1) magnetic thin film that is ferromagnetic and has a large spin polarizability at room temperature can be obtained.

Further, the tunnel magnetoresistance effect element of the present invention has a plurality of ferromagnetic layers on a substrate, and at least one of the ferromagnetic layers has a structure of Co ₂ Fe having any one of L2 ₁ , B2, and A2 structures. _x Cr _1-x Al (here, 0 ≦ x ≦ 1) is made of a magnetic thin film.
The ferromagnetic layer includes a fixed layer and a free layer, and the free layer has a structure of any one of L2 ₁ , B2, and A2 structures, where Co ₂ F _x Cr _{1 -x} Al (where 0 ≦ x ≦ 1) It is preferable to use a magnetic thin film. Further, the Co ₂ Fe _x Cr _1-x Al thin film can be formed without heating the substrate. In this case, the substrate may be any one of thermally oxidized Si, glass, MgO single crystal, GaAs single crystal, and Al ₂ O ₃ single crystal. Further, a buffer layer may be provided between the substrate and the Co ₂ Fe _x Cr _1-x Al thin film. This buffer layer can be composed of at least one of Al, Cu, Cr, Fe, Nb, Ni, Ta, and NiFe.

  According to the above configuration, a tunneling magneto-resistance effect element having a large TMR at a low external magnetic field at room temperature can be obtained.

Further, the giant magnetoresistive element of the present invention has a plurality of ferromagnetic layers on a substrate, and at least one of the ferromagnetic layers has a structure of Co ₂ Fe having any one of L2 ₁ , B2, and A2 structures. _{(where, 0 ≦ x ≦ 1) x} Cr 1-x Al made of a magnetic thin film, characterized in that a structure in which current flows in a direction perpendicular to the film surface.
The ferromagnetic layer includes a fixed layer and a free layer, and the free layer has a structure of any one of L2 ₁ , B2, and A2 structures, where Co ₂ F _x Cr _{1 -x} Al (where 0 ≦ x ≦ 1) It is preferable to use a magnetic thin film. The Co ₂ Fe _x Cr _1-x Al thin film can be formed without heating the substrate. A buffer layer may be provided between the substrate and the Co ₂ Fe _x Cr _1-x Al thin film. The substrate may be any one of thermally oxidized Si, glass, MgO single crystal, GaAs single crystal, and Al ₂ O ₃ single crystal. Further, the buffer layer can be composed of at least one of Al, Cu, Cr, Fe, Nb, Ni, Ta, and NiFe.

  According to the above configuration, a giant magnetoresistance effect element having a large GMR at a low external magnetic field at room temperature can be obtained.

Further, in the magnetic device of the present invention, a Co ₂ F _x Cr _1-x Al (here, 0 ≦ x ≦ 1) magnetic thin film having any one of L2 ₁ , B2, and A2 structures is formed on a substrate. It is characterized by being made. In this case, a tunnel magnetoresistive element or a giant magnetoresistive element whose free layer is made of a magnetic thin film of Co ₂ F _x Cr _1-x Al (here, 0 ≦ x ≦ 1) may be used.
Preferably, the tunnel magnetoresistance effect element or the giant magnetoresistance effect element is manufactured without heating the substrate.
It is also possible to use a tunnel magnetoresistive element or a giant magnetoresistive element in which a buffer layer is disposed between a substrate and a Co ₂ F _x Cr _1-x Al (here, 0 ≦ x ≦ 1) thin film. it can. A tunnel magnetoresistive element or a giant magnetoresistive element in which the substrate is any one of thermally oxidized Si, glass, MgO single crystal, GaAs single crystal, and Al ₂ O ₃ single crystal can be used. As the buffer layer, a tunnel magnetoresistive element or a giant magnetoresistive element using at least one of Al, Cu, Cr, Fe, Nb, Ni, Ta, and NiFe may be used.

  According to the above configuration, it is possible to obtain a magnetic device using a magnetoresistive element having a large TMR and a large GMR at a low external magnetic field at room temperature.

Further, the magnetic head and the magnetic recording apparatus of the present invention may be configured such that a Co ₂ F _x Cr _1-x Al (here, 0 ≦ x ≦ 1) magnetic thin film having any one of L2 ₁ , B2, and A2 structures. It is characterized by being formed on a substrate.
In the above structure, preferably, a tunnel magnetoresistive element or a giant magnetoresistive element whose free layer is a magnetic thin film of Co ₂ F _x Cr _1-x Al (here, 0 ≦ x ≦ 1) is used. A tunnel magnetoresistive element or a giant magnetoresistive element manufactured without heating the substrate may be used.
Further, a tunnel magnetoresistive element or a giant magnetoresistive element in which a buffer layer is provided between a substrate and a Co ₂ F _x Cr _1-x Al (here, 0 ≦ x ≦ 1) thin film may be used. Good. Further, a tunnel magnetoresistive element or a giant magnetoresistive element whose substrate is any one of thermally oxidized Si, glass, MgO single crystal, GaAs single crystal, and Al ₂ O ₃ single crystal can also be used. Furthermore, a tunnel magnetoresistive element or a giant magnetoresistive element in which the buffer layer is made of at least one of Al, Cu, Cr, Fe, Nb, Ni, Ta, and NiFe may be used.

  According to the above configuration, a large-capacity, high-speed magnetic head and magnetic recording device can be obtained by using a magnetoresistive element having a large TMR and a large GMR at a low external magnetic field at room temperature.

According to the present invention, a magnetic thin film using Co ₂ F _x Cr _1-x Al (here, 0 ≦ x ≦ 1) having any one of the L2 ₁ , B2, and A2 structures can be formed at room temperature. It can be manufactured without heating. Further, it shows ferromagnetic properties and has a large spin polarizability.

Further, the present invention relates to a giant magnetoresistive element using a Co ₂ F _x Cr _1-x Al (here, 0 ≦ x ≦ 1) magnetic thin film having any one of the L2 ₁ , B2, and A2 structures. According to this, at room temperature, a very large GMR can be obtained with a low external magnetic field. Similarly, a very large TMR can be obtained by the tunnel magnetoresistive element.

Further, various magnetoresistance effect elements using a Co ₂ F _x Cr _1-x Al (here, 0 ≦ x ≦ 1) magnetic thin film having any one of the L2 ₁ , B2, and A2 structures of the present invention. Is applied to various magnetic devices, such as a super-gigabit large-capacity, high-speed magnetic head and a non-volatile, high-speed MRAM, thereby realizing a novel magnetic device. In this case, the magnetization reversal magnetic field due to spin injection is small due to the small saturation magnetization, so that magnetization reversal can be realized with low power consumption, and efficient spin injection into semiconductors is possible, and the possibility of developing spin FETs It can be widely used as a key material for developing the spin electronics field.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. The same reference numerals are used for the same or corresponding members in each drawing.
First, a first embodiment of the magnetic thin film of the present invention will be described.
FIG. 1 is a sectional view of the magnetic thin film according to the first embodiment of the present invention. As shown in FIG. 1, a magnetic thin film 1 according to the present invention has a Co ₂ Fe _x Cr _1-x Al thin film 3 disposed on a substrate 2 at room temperature. Here, 0 ≦ x ≦ 1. The Co ₂ Fe _x Cr _1-x Al thin film 3 is ferromagnetic at room temperature, has an electric resistivity of about 190 μΩ · cm, and has any one of the L2 ₁ , B2, and A2 structures without heating the substrate. It has two structures.
Further, by heating the substrate on which the Co ₂ Fe _x Cr _1-x Al thin film 3 is disposed, it is easy to obtain the L _{2 1} structure Co ₂ F _x Cr _1-x Al thin film 3 having a large spin polarizability. Here, the thickness of the Co ₂ Fe _x Cr _1-x Al thin film 3 on the substrate 2 may be 1 nm or more and 1 μm or less.

FIG. 2 is a sectional view of a modification of the magnetic thin film according to the first embodiment of the present invention. As shown in FIG. 2, the magnetic thin film 5 of the present invention, in the structure of the magnetic thin film 1 in FIG. 1, Further, the substrate 2 and _{Co 2 Fe x Cr 1-x} Al ( wherein, 0 ≦ x ≦ 1) thin film 3, a buffer layer 4 is inserted. By inserting the buffer layer 4, the crystallinity of the Co ₂ F _x Cr _1-x Al (here, 0 ≦ x ≦ 1) thin film 3 on the substrate 1 can be further improved.

The substrate 2 used in the magnetic thin film 1 and 5, can be used thermally oxidized Si, polycrystal such as glass, MgO, a single crystal such as Al ₂ O _3, GaAs. Further, as the buffer layer 4, Al, Cu, Cr, Fe, Nb, Ni, Ta, NiFe, or the like can be used.
The thickness of the Co ₂ Fe _x Cr _1-x Al (here, 0 ≦ x ≦ 1) thin film 3 may be 1 nm or more and 1 μm or less. If the film thickness is less than 1 nm, it will be difficult to obtain substantially any one of the L2 ₁ , B2, and A2 structures described later, and if the film thickness exceeds 1 μm, application as a spin device will be difficult. Is not preferred.

Next, the operation of the magnetic thin film used in the first embodiment having the above configuration will be described.
FIG. 3 is a diagram schematically illustrating a structure of Co ₂ Fe _x Cr _1-x Al (here, 0 ≦ x ≦ 1) used for the magnetic thin film according to the first embodiment of the present invention. The structure shown in the figure shows a structure that is eight times (double the lattice constant) the conventional unit cell of bcc (body-centered cubic lattice).
In the L2 ₁ structure of Co ₂ Fe _x Cr _1-x Al, the composition ratio of Fe and Cr is F _x Cr _1-x (where 0 ≦ x ≦ 1) at the position I in FIG. Al is placed at the position II, and Co is placed at the positions III and IV.
Further, the B2 structure of Co ₂ Fe _x Cr _1-x Al has a structure in which Fe, Cr and Al are irregularly arranged at positions I and II in FIG. In this case, the composition ratio of Fe and Cr is set so as to _satisfy FexCr1 _-x (where 0≤x≤1).
Further, the A2 structure of Co ₂ Fe _x Cr _1-x Al has a structure in which Co, Fe, Cr and Al are irregularly substituted. In this case, the composition ratio of Fe and Cr is set so as to _satisfy FexCr1 _-x (where 0≤x≤1).

Next, the magnetic properties of the magnetic thin films 1 and 5 used in the first embodiment having the above configuration will be described.
The Co ₂ Fe _x Cr _1-x Al (here, 0 ≦ x ≦ 1) thin film 3 having the above structure is ferromagnetic at room temperature and has any of the L2 ₁ , B2, and A2 structures without heating the substrate. A Co ₂ Fe _x Cr _1-x Al thin film having one structure is obtained.
Further, the Co ₂ F _x Cr _1-x Al thin film 3 (here, 0 ≦ x ≦ 1) having any of the L2 ₁ , B2, and A2 structures even in a very thin film having a thickness of about several nm. One structure is obtained.
Here, the B2 structure of the Co ₂ Fe _x Cr _1-x Al (here, 0 ≦ x ≦ 1) thin film is a unique substance that has not been obtained conventionally. The B2 structure is similar to the L2 ₁ structure, except that in the L2 ₁ structure, Cr (Fe) and Al atoms are regularly arranged, whereas the B2 structure is irregularly arranged. That is. The A2 structure is a structure in which Co, Fe, Cr and Al are irregularly substituted. These differences can be measured by X-ray diffraction.
In the composition x of the Co ₂ Fe _x Cr _1-x Al thin film 3, if the composition is in the range of 0 ≦ x ≦ 0.8, it is particularly necessary to obtain any one of the structures of L 2 ₁ and B 2 without heating the substrate. Can be. When 0.8 ≦ x ≦ 1.0, an A2 structure is obtained.
Further, in the composition x, within a range of 0 ≦ x ≦ 1, a Co ₂ Fe _x Cr _1-x Al thin film is formed on a heated substrate, or a heat treatment is performed after forming the film without heating the substrate. , L2 ₁ or B2 structures are obtained.

It is difficult to experimentally clarify that the magnetic thin films 1 and 5 having the above configuration are half-metals. However, qualitatively, a tunnel magnetoresistive effect element having a tunnel junction is manufactured, and the tunnel magnetoresistance effect element exceeds 100%. If a very large TMR is shown, it can be considered to be half-metallic.
The Co ₂ F _x Cr _1-x Al (0 ≦ x ≦ 1) thin film 3 of the present invention is used as a ferromagnetic layer on one side of the insulating film, and the other ferromagnetic layer of the insulating film has a spin polarization of 0.5. As a result of manufacturing a tunnel magnetoresistance effect element using a CoFe alloy, a large TMR exceeding 100% was obtained.

This indicates that the Co ₂ F _x Cr _1-x Al (0 ≦ x ≦ 1) thin film 3 has a spin polarizability of P = 0.7 or more in consideration of the equation (1). The reason why such a large TMR can be obtained is that the Co ₂ F _x Cr _1-x Al (0 ≦ x ≦ 1) thin film 3 has a large spin polarizability, _It is in the discovery that any one of the ₁ , B2 and A2 structures can be obtained. Thereby, according to the magnetic thin films 1 and 5 of the present invention, it is not necessary to heat the substrate, and the Co ₂ F _x Cr _1-x Al (0 ≦ x ≦ 1) thin film 3 has a ferromagnetic property with a thickness of 1 nm or more. Can be obtained. This is because the surface of the tunnel junction can be made clean and sharp without oxidizing the surface or increasing the surface roughness. It is presumed that a large TMR can be obtained.

Next, a second embodiment of the magnetoresistive element using the magnetic thin film of the present invention will be described.
FIG. 4 is a diagram showing a cross section of a magnetoresistive element using a magnetic thin film according to a second embodiment of the present invention. FIG. 4 shows the case of a tunnel magnetoresistance effect element. As shown in FIG. 1, a tunnel magnetoresistive element 10 has, for example, a Co ₂ F _x Cr _1-x Al (0 ≦ x ≦ 1) thin film 3 disposed on a substrate 2 and an insulating layer serving as a tunnel layer. 11, a ferromagnetic layer 12, and an antiferromagnetic layer 13 are sequentially laminated.

Here, the antiferromagnetic layer 13 is used for a so-called spin bubble type structure for fixing the spin of the ferromagnetic layer 12. In this structure, the Co ₂ F _x Cr _1-x Al (0 ≦ x ≦ 1) thin film 3 is called a free layer, and the ferromagnetic layer 12 is called a pinned layer. Further, the ferromagnetic layer 12 may have either a single-layer structure or a multi-layer structure.
The insulating layer 13 is made of AlO _x which is an oxide of Al ₂ O ₃ or Al, the ferromagnetic layer 14 is made of CoFe, NiFe or a composite film of CoFe and NiFe, and the antiferromagnetic layer 13 is made of IrMn. Etc. can be used.
Further, it is preferable that a nonmagnetic electrode layer 14 serving as a protective film is further deposited on the antiferromagnetic layer 13 of the tunnel magnetoresistance effect element 10 of the present invention.

FIG. 5 is a view showing a cross section of a modification of the magnetoresistive element using the magnetic thin film according to the second embodiment of the present invention. In a tunnel magnetoresistive element 15 which is a magnetoresistive element using the magnetic thin film of the present invention, a buffer layer 4 and a Co ₂ F _x Cr _1-x Al (0 ≦ x ≦ 1) thin film 3 are disposed on a substrate 2. It has a structure in which an insulating layer 11 serving as a tunnel layer, a magnetic thin film 12, an antiferromagnetic layer 13, and a nonmagnetic electrode layer 14 serving as a protective film are sequentially stacked. FIG. 5 differs from the structure of FIG. 4 in that a buffer layer 4 is further provided in the structure of FIG. Other structures are the same as those in FIG.

FIG. 6 is a view showing a cross section of a modification of the magnetoresistive element using the magnetic thin film according to the second embodiment of the present invention. Tunnel magnetoresistance effect element 20 is a magnetoresistance effect element using a magnetic thin film of the present invention, the buffer layer 4 on the substrate 2 and _{Co 2 Fe x Cr 1-x} Al (0 ≦ x ≦ 1) thin film 3 distribution An insulating layer 11 serving as a tunnel layer, a Co ₂ F _x Cr _1-x Al (0 ≦ x ≦ 1) thin film 16, an antiferromagnetic layer 13, and a nonmagnetic electrode layer 14 serving as a protective film are provided. It has a structure that is sequentially laminated. FIG. 6 differs from the structure of FIG. 5 in that the ferromagnetic layer 12 serving as the pinned layer in FIG. 4 also has a Co ₂ F _x Cr _1-x Al (0 ≦ x ≦ 1) thin film 16 which is a magnetic thin film of the present invention. This is the point that was used. Other structures are the same as those in FIG.
When a voltage is applied to the tunneling magnetoresistive element 10, 15, 20, is applied between the _{Co 2 Fe x Cr 1-x} Al (0 ≦ x ≦ 1) thin film 3 or the buffer layer 4 and the electrode layer 14 . Further, the external magnetic field is applied in parallel in the film plane. The current from the buffer layer 4 to the electrode layer 14 can be caused to flow by a CPP structure in which a current flows in a direction perpendicular to the film surface.

Here, the substrate 2 used for the tunneling magnetoresistive element 10, 15 is thermally oxidized Si, polycrystal such as glass, MgO, may be Al ₂ O _3, a single crystal such as GaAs.
Further, as the buffer layer 4, Al, Cu, Cr, Fe, Nb, Ni, Ta, NiFe, or the like can be used.
The thickness of the Co ₂ F _x Cr _1-x Al (0 ≦ x ≦ 1) thin film 3 may be 1 nm or more and 1 μm or less. If this film thickness is less than 1 nm, it becomes substantially difficult to obtain any one of the L2 ₁ , B2 and A2 structures, and if this film thickness exceeds 1 μm, application as a tunnel magnetoresistive element is made. It is difficult and not preferable. The tunnel magnetoresistive elements 10, 15, and 20 of the present invention having the above-described structure are used for forming a normal thin film forming method such as a sputtering method, a vapor deposition method, a laser ablation method, and an MBE method, and forming electrodes having a predetermined shape. It can be manufactured by using the masking process described above.

Next, operations of tunnel magnetoresistive elements 10 and 15 which are magnetoresistive elements using the magnetic thin film of the present invention will be described.
The magnetoresistive elements 10 and 15 using the magnetic thin film of the present invention use two ferromagnetic layers 3 and 12, one of which has an antiferromagnetic layer 13 in close proximity, and the adjacent ferromagnetic layer 12 (pin layer). Is used, and when an external magnetic field is applied, a Co ₂ F _x Cr _1-x Al (0 ≦ x ≦ 1) thin film, which is a free layer that is the other ferromagnetic layer, is applied when an external magnetic field is applied. Only the spins of 3 are reversed.
As a result, the magnetization of the ferromagnetic layer 12 is fixed in one direction by the exchange interaction with the antiferromagnetic layer 13 due to the spin valve effect, so that the free layer of Co ₂ F _x Cr _1-x Al ( 0 ≦ x ≦ 1) The parallel and antiparallel spins of the thin film 3 can be easily obtained, and the ferromagnetic layer is a Co ₂ F _x Cr _1-x Al (0 ≦ x ≦ 1) thin film 3 so that the spin is small. Since the polarizability is large, the TMR of 10, 15 of the tunnel magnetoresistance effect element of the present invention becomes very large.
At this time, since the magnetization of the Co ₂ F _x Cr _1-x Al (0 ≦ x ≦ 1) thin film 3 which is a free layer is small, the magnetization reversal can be caused by a small demagnetizing field and a correspondingly small magnetic field.
Thus, the tunnel magnetoresistive elements 10 and 15 of the present invention are suitable for magnetic devices such as MRAM that require magnetization reversal with low power.

Next, the operation of the tunnel magnetoresistive element 20 which is a magnetoresistive element using the magnetic thin film of the present invention will be described.
Tunnel magnetoresistance effect element 20 further, the ferromagnetic layer 16 of the pinned layer is also free layer ferromagnetic _{Co 2 Fe x Cr 1-x} Al (0 ≦ x ≦ 1) the same Co ₂ and thin film 3 Fe _x Cr _{Since 1-x} Al (0 ≦ x ≦ 1) is used, the denominator of the above equation (1) becomes smaller, and the TMR of the tunnel magnetoresistance effect element of the present invention becomes larger. Thus, the tunneling magneto-resistance effect element 20 of the present invention is suitable for a magnetic device such as an MRAM that requires low-power magnetization reversal.

Next, a third embodiment according to a magnetoresistive element using the magnetic thin film of the present invention will be described.
FIG. 7 is a view showing a cross section of a magnetoresistive element using a magnetic thin film according to the third embodiment of the present invention. The magnetoresistance effect element using the magnetic thin film of the present invention is a giant magnetoresistance effect element. As shown in the figure, a giant magnetoresistive element 30 has a buffer layer 4 and a Co ₂ F _x Cr _1-x Al (0 ≦ x ≦ 1) thin film 3 of the present invention, which becomes a ferromagnetic material, on a substrate 2. It has a structure in which a nonmagnetic metal layer 21, a ferromagnetic layer 22, and a nonmagnetic electrode layer 14 serving as a protective film are sequentially laminated.
Here, a voltage is applied between the buffer layer 4 and the electrode layer 14 of the giant magnetoresistive element. Further, the external magnetic field is applied in parallel in the film plane. The current from the buffer layer 4 to the electrode layer 14 can be caused to flow by a CPP structure that is a type in which a current flows in a direction perpendicular to the film surface.

FIG. 8 is a view showing a cross section of a modification of the magnetoresistive element using the magnetic thin film according to the third embodiment of the present invention. The giant magnetoresistive element 35 of the present invention is different from the giant magnetoresistive element 30 of FIG. 7 in that the antiferromagnetic layer 13 is provided between the ferromagnetic layer 22 and the electrode layer 14 and a spin valve type giant magnetoresistive element 35 is formed. This is a magnetoresistive element. Other structures are the same as those in FIG.
The antiferromagnetic layer 13 has a function of fixing the spin of the ferromagnetic layer 22 which is to be a pinned layer adjacent thereto. Here, a voltage is applied between the buffer layer 4 and the electrode layer 14 of the giant magnetoresistive elements 30 and 35. Further, the external magnetic field is applied in parallel in the film plane. The current from the buffer layer 4 to the electrode layer 14 can be caused to flow by a CPP structure which is a type in which a current flows in a direction perpendicular to the film surface.

The giant magnetoresistance substrate 2 of effect elements 30 and 35, thermal oxidation Si, polycrystal such as glass, further, it is possible to use MgO, a single crystal such as Al ₂ O _3, GaAs. Further, as the buffer layer 4, Al, Cu, Cr, Fe, Nb, Ni, Ta, NiFe, or the like can be used. As the nonmagnetic metal layer 21, Cu, Al, or the like can be used. Further, it is possible to use _{CoFe, NiFe, Co 2 Fe x} Cr 1-x Al (0 ≦ x ≦ 1) or any one of a thin film, or a composite film made of these materials as the ferromagnetic layer 22. The antiferromagnetic layer 13 can be made of IrMn or the like.
The thickness of the Co ₂ Fe _x Cr _1-x Al (0 ≦ x ≦ 1) thin film 3 may be 1 nm or more and 1 μm or less. If this film thickness is less than 1 nm, it becomes substantially difficult to obtain any one of the L2 ₁ , B2, and A2 structures, and if this film thickness exceeds 1 μm, application as a giant magnetoresistive element is made. It is difficult and not preferable.
The giant magnetoresistive elements 30 and 35 of the present invention having the above-described structure are formed by a normal thin film forming method such as a sputtering method, a vapor deposition method, a laser ablation method, an MBE method, and a mask for forming an electrode having a predetermined shape. It can be manufactured using a process or the like.

Giant magnetoresistance effect element 30 is a magnetoresistance effect element using a magnetic thin film of the present invention, the spin polarization of _{Co 2 Fe x Cr 1-x} Al (0 ≦ x ≦ 0.6) thin film 3 is a ferromagnetic layer Since the ratio is large, spin-dependent scattering is large, and a large magnetoresistance, that is, GMR is obtained.

Next, in the case of the spin valve type giant magnetoresistive element 35 which is a magnetoresistive element using a magnetic thin film, the spin of the ferromagnetic layer 22 which is a pin layer is fixed by the antiferromagnetic layer 13. in here applying an external magnetic field, the spin of _{Co 2 Fe x Cr 1-x} Al (0 ≦ x ≦ 1) thin film 3 is a free layer is in a state of parallel and anti-parallel by an external magnetic field. The Co ₂ Fe _x Cr _1-x Al (0 ≦ x ≦ 1) thin film 3 has a large spin polarizability and therefore a large spin-dependent scattering, and a large resistance, so that a decrease in GMR due to the antiferromagnetic layer 13 can be suppressed. .

Next, a fourth embodiment according to the magnetic device using the magnetoresistive element formed of the magnetic thin film of the present invention will be described.
As shown in FIGS. 1 to 8, various magnetoresistive elements using the magnetic thin film of the present invention have a very large TMR or GMR at room temperature in a low magnetic field.
FIG. 9 is a diagram schematically illustrating resistance when an external magnetic field is applied to a tunnel magnetoresistive element or a giant magnetoresistive element, which is a magnetoresistive element using the magnetic thin film of the present invention. The horizontal axis in the figure is the external magnetic field applied to the magnetoresistive element using the magnetic thin film of the present invention, and the vertical axis is the resistance. Here, the magnetoresistance effect element using the magnetic thin film of the present invention is sufficiently applied with a voltage necessary for obtaining a giant magnetoresistance effect and a tunnel magnetoresistance effect.

As shown in the figure, the resistance of the magnetoresistive element using the magnetic thin film of the present invention shows a large change due to an external magnetic field. When an external magnetic field is applied from the area (I), the external magnetic field is reduced to zero, and the external magnetic field is reversed and increased, the resistance changes from the minimum resistance to the maximum resistance in the area (II) to the area (III). I do. Here, the external magnetic field in the region (II) and H _1.

Further, when the external magnetic field is increased, a resistance change from the region (III) to the region (V) via the region (IV) is obtained. As a result, the magnetoresistive effect element using the magnetic thin film of the present invention can provide the ferromagnetic layer 22 and the free layer of Co ₂ Fe _x Cr _1-x Al in the external magnetic field of the region (I) and the region (V). (0 ≦ x ≦ 1) The spins of the thin film 3 are parallel, and in the region (III), they are antiparallel.

Here, the magnetoresistance change rate is expressed by the following equation (2) when an external magnetic field is applied, and the larger this value is, the more desirable the magnetoresistance change rate is.
Magnetoresistance change rate = (maximum resistance−minimum resistance) / minimum resistance (%) (2)
Thus, a magnetoresistive effect element using a magnetic thin film of the present invention, as shown in FIG. 9, by adding only slightly larger magnetic field than the H ₁ field is from zero, i.e. a low magnetic field, a large magnetoresistive change Rate is obtained.

As described with reference to FIG. 9, a magnetoresistive effect element using the magnetic thin film of the present invention exhibits a large TMR or GMR in a low magnetic field at room temperature. Therefore, when used as a magnetoresistive sensor, a highly sensitive magnetic element can be obtained. be able to.
Further, the magnetoresistive effect element using the magnetic thin film of the present invention exhibits a large TMR or GMR in a low magnetic field at room temperature. Therefore, a highly sensitive magnetic head for reading and various magnetic recordings using these magnetic heads are provided. The device can be configured.
Further, for example, an MTJ element, which is a magnetoresistive element using the magnetic thin film of the present invention, is arranged in a matrix, and a current is applied to a separately provided wiring to apply an external magnetic field. By controlling the magnetization of the ferromagnetic material of the free layer constituting the MTJ element to be parallel and antiparallel to each other by an external magnetic field, "1" and "0" are recorded.
Furthermore, a magnetic device such as an MRAM can be configured by performing reading using the TMR effect or the like.
Further, in the GMR element having the CPP structure, which is the magnetoresistive element of the present invention, since the GMR is large, the capacity of a magnetic device such as a hard disk drive (HDD) or MRAM can be increased.

Hereinafter, examples of the present invention will be described.
A 100 nm-thick Co ₂ Fe _x Cr _{1 -x} Al thin film 3 was formed on a thermally oxidized Si substrate 2 using a high frequency sputtering apparatus while changing the substrate temperature.
FIG. 10 is a diagram showing the result of measuring the X-ray diffraction of the Co ₂ Fe _0.5 Cr _0.5 Al thin film 3. The horizontal axis of the figure is the diffraction angle 2θ (degrees), and the vertical axis is the intensity of the diffracted X-rays on a Log (logarithmic) scale. The downward arrow (↓) shown in the figure represents the diffraction intensity from each surface of the crystal of the Co ₂ Fe _0.5 Cr _0.5 Al thin film 3. As shown in FIG. 10, the substrate was crystallized without heating, and the diffraction image analysis revealed that it had a B2 structure with a lattice constant a = 5.72 °. Further, even when the substrate was heated from room temperature to 550 ° C., the diffraction image did not change much, indicating that it was thermally stable.

On the other hand, a Co ₂ F _x Cr _1-x Al thin film (here, 0 ≦ x ≦ 1) 3 is formed on the substrate 2 by using an appropriate buffer layer 4 such as Cr or Fe, or _{When the} amount of Fe substitution for Cr in the ₂ F _x Cr _1-x Al (here, 0 ≦ x ≦ 1) thin film 3 was reduced, a diffraction X-ray peak of the (111) plane was confirmed near 2θ = 27 degrees. . This indicates that the Co ₂ Fe _x Cr _1-x Al (here, 0 ≦ x ≦ 1) thin film 3 has an L2 ₁ structure.

Next, the magnetic characteristics of the Co ₂ Fe _0.5 Cr _0.5 Al thin film 3 shown in FIG. 10 will be described.
FIG. 11 is a diagram showing the magnetization characteristics of the Co ₂ Fe _0.5 Cr _0.5 Al thin film 3 at room temperature. The horizontal axis of the figure is the magnetic field H (Oe), and the vertical axis is the magnetization (emu / cm ³ ). As shown in the figure, the Co ₂ Fe _0.5 Cr _0.5 Al thin film 3 shows a hysteresis and is a ferromagnetic material. From the figure, it was found that the saturation magnetization was about 300 emu / cm ³ and the coercive force was 5 Oersted (Oe).

Magnetic thin films 1 and 5 using the same Co ₂ Fe _0.5 Cr _0.5 Al thin film 3 were produced by changing the temperature of the substrate 2, but the saturation magnetization and the coercive force hardly changed up to 400 ° C. Therefore, suggesting that already good crystallinity B2 structure of Co ₂ Fe _0.5 Cr _0.5 Al thin film 3 at room temperature is obtained. Furthermore, the electrical resistivity of the Co ₂ Fe _0.5 Cr _0.5 Al thin film 3 was measured at room temperature, and as a result, the electrical resistivity was about 190 μΩ · cm. This value is equivalent to 200 μΩ · cm of the antiferromagnetic substance InMn.

Similarly, in the Co ₂ Fe _x Cr _1-x Al (here, 0 ≦ x ≦ 1) thin film 3, Co ₂ Fe _x having a composition of x = 0, 0.4, 0.6, 1.0 A Cr _1-x Al thin film 3 was produced at room temperature. When the Co ₂ Fe _x Cr _1-x Al thin film 3 thus manufactured was evaluated by X-ray diffraction, each of the obtained films showed any _{one of} the L2 ₁ , B2, and A2 structures. Further, the electrical resistivity of the Co ₂ Fe _x Cr _1-x Al thin film 3 tends to decrease as the composition x increases, and was about 100 μΩ · cm when x = 1.0.

The spin-valve tunnel magnetoresistive element 15 shown in FIG. 5 was manufactured at room temperature. Cr (5 nm) / Co ₂ Fe _0.4 Cr _0.6 Al (10 nm) / AlO _x (1.2 nm) / CoFe was formed on the thermally oxidized Si substrate 2 by using a high frequency sputtering device and a metal mask as a buffer layer 4. (5 nm) / NiFe (5 nm) / IrMn (10 nm) / Cr (5 nm) were sequentially stacked to fabricate a tunnel magnetoresistive element 15. The numbers in parentheses are the respective film thicknesses.
Cr is a buffer layer 4, Co ₂ Fe _0.4 Cr _0.6 Al thin film 3 is a ferromagnetic free layer, AlO _x is a tunnel insulating layer 11, CoFe and NiFe are pin layers of a ferromagnetic layer 12, a ferromagnetic material composed of a composite film, IrMn is the antiferromagnetic layer 13 and has a role of fixing the spin of the CoFe / NiFe ferromagnetic layer 12. Then, Cr on IrMn, which is the antiferromagnetic layer 13, is the protective film 14. In addition, a uniaxial anisotropy was introduced in the film plane by applying a magnetic field of 100 Oe during film formation.

An external magnetic field was applied to the tunnel magnetoresistive element 15, and the magnetoresistance was measured at room temperature. FIG. 12 is a diagram illustrating the magnetic field dependence of the resistance of the tunnel magnetoresistive element 15. The horizontal axis in the figure is the external magnetic field H (Oe), and the vertical axis is the resistance (Ω). From this, the TMR was determined to be 107%. The TMR obtained by the tunnel magnetoresistive element 15 of the present invention is very large considering that the TMR of the conventional tunnel magnetoresistive element is about 50% at the maximum, and the spin rate of the Co ₂ Fe _0.4 Cr _0.6 Al thin film is large. It was found that the polarizability was as high as about 0.7.

A spin-valve tunnel magnetoresistive element 15 similar to that of Example 2 was produced except that 20 nm of Fe was used as the buffer layer 4 and that the Co ₂ Fe _0.6 Cr _0.4 Al thin film 3 was used. An external magnetic field was applied to the tunnel magnetoresistive element 15, and the magnetoresistance was measured at room temperature. As a result, a TMR of 92% was obtained. From this, it was found that the spin polarizability of the Co ₂ Fe _0.6 Cr _0.4 Al thin film was high.

A spin-valve tunneling magneto-resistance effect element 10 was produced in the same manner as in Example 3 without using the buffer layer 4. In this case, the Co ₂ Fe _0.4 Cr _0.6 Al magnetic thin film had a B2 structure. An external magnetic field was applied to the tunnel magnetoresistance effect element 10, and the magnetoresistance was measured at room temperature.
FIG. 13 is a diagram showing the magnetic field dependence of the magnetoresistance of the tunnel magnetoresistance effect element 10. The horizontal axis in the figure is the external magnetic field H (Oe), the left vertical axis is the resistance (Ω), and the right vertical axis is the TMR (%) calculated from the measured resistance. The solid and dotted lines in the figure show the resistance values when the external magnetic field is swept.
This resulted in about 11% TMR at room temperature. Further, at a temperature of 77K, a TMR of 32% was obtained. The structure of the Co ₂ Fe _0.4 Cr _0.6 Al magnetic thin film 3 in this case is a B2 structure, and even though the buffer layer 4 was not used, such a relatively large TMR was obtained at room temperature. From this, it was found that the Co ₂ Fe _0.4 Cr _0.6 Al magnetic thin film has a large spin polarizability even in the B2 structure.

A spin-valve tunneling magneto-resistance effect element 10 using the Co ₂ FeAl magnetic thin film 3 was fabricated in the same manner as in Example 3 without using the buffer layer 4. In this case, the Co ₂ FeAl magnetic thin film 3 had an A2 structure. An external magnetic field was applied to the tunnel magnetoresistance effect element 10, and the magnetoresistance was measured at room temperature and a low temperature of 5K. As a result, a large TMR of 8% at room temperature and 42% at low temperature was obtained. This suggests that the Co ₂ FeAl magnetic thin film having the A2 structure also has a large spin polarizability.

Without using the buffer layer 4, Co ₂ FeAl (10 nm) / AlO _x (1.4 nm) / CoFe (3 nm) / Ta (10 nm) which are tunneling magnetoresistive elements of a coercive force difference type were formed on a thermally oxidized Si substrate. Was fabricated at room temperature. Here, the numbers in parentheses are the respective film thicknesses. The coercive force difference type tunneling magneto-resistance effect element is a tunneling magneto-resistance effect element utilizing a difference in coercive force between Co ₂ FeAl and CoFe which are ferromagnetic substances. The TMR of this coercive force difference type tunneling magneto-resistance effect element has a difference in magnetoresistance depending on whether magnetization is parallel or anti-parallel to each other, similarly to the spin valve type tunneling magneto-resistance effect element.
The TMR value obtained by the manufactured coercive force difference type tunnel magnetoresistance effect element was 8% at room temperature and 42% at a low temperature of 5K. The crystal structure of the Co ₂ FeAl thin film 3 when fabricated on a thermally oxidized Si substrate without heating the substrate was an A2 structure.

Next, this tunnel magnetoresistance effect element was heat-treated at various temperatures in a vacuum, and its TMR characteristics were measured. As a result, the TMR when heat-treated at 300 ° C. for 1 hour was 28% at room temperature, and 55% at a low temperature of 5K, which was much higher than the TMR when manufactured at room temperature. When the crystal structure of the Co ₂ FeAl thin film at this time was measured by X-ray diffraction, the crystal structure was an L2 ₁ structure.
Therefore, the improvement in TMR due to the heat treatment is due to the change in the crystal structure of the Co ₂ FeAl thin film from the A2 structure to the L2 ₁ structure, suggesting that the spin polarizability of the L2 ₁ structure is larger than that of the A2 structure. I have.

A spin-valve tunneling magneto-resistance effect element 10 was manufactured in the same manner as in Example 2 except that GaAs was used as the substrate 4. In this case, the Co ₂ Fe _0.4 Cr _0.6 Al magnetic thin film 3 had an L2 ₁ structure. An external magnetic field was applied to the tunnel magnetoresistance effect element 10, and the magnetoresistance was measured at room temperature. As a result, a large TMR of 125% was obtained at room temperature, suggesting that the spin polarizability of the Co ₂ Fe _0.4 Cr _0.6 Al magnetic thin film having the L2 ₁ structure was very large.

A spin valve type giant magnetoresistive element 35 shown in FIG. 8 was produced at room temperature. Using a high-frequency sputtering device and a metal mask, Al (100 nm) / Co ₂ Fe _0.5 Cr _0.5 Al (5 nm) / Cu (6 nm) / Co ₂ Fe _0.5 Cr _0.5 Al (5 nm) / NiFe (5 nm) / IrMn (10 nm) / Al (100 nm) were sequentially deposited to produce a multilayer structure of a spin valve type giant magnetoresistance effect element. The numbers in parentheses are the respective film thicknesses.

Here, Al is the buffer layer 4, Co ₂ Fe _0.5 Cr _0.5 Al is the thin film 3 serving as a free layer, and Cu is the nonmagnetic metal layer 21 for exhibiting a giant magnetoresistance effect. The two-layer structure of Co ₂ Fe _0.5 Cr _0.5 Al (5 nm) and NiFe (5 nm) is a ferromagnetic layer 22 serving as a pinned layer. IrMn is the antiferromagnetic layer 13 and has a role of fixing the spin of the ferromagnetic layer 22 serving as a pinned layer. The uppermost Al layer is the electrode 14. In addition, a uniaxial anisotropy was introduced in the film plane by applying a magnetic field of 100 Oe during film formation. The deposited multilayer film was finely processed using electron beam lithography and an Ar ion milling device to produce a giant magnetoresistive element 35 of 0.5 μm × 1 μm.

A voltage was applied between the upper and lower electrodes 4 and 14 of the device, a current was passed in the direction perpendicular to the film surface, and an external magnetic field was applied to measure the magnetoresistance at room temperature. As a result, a magnetic resistance of about 8% was obtained. This value is eight times as large as the conventional magnetoresistive element having a spin valve type CPP structure with a magnetoresistance of less than 1%.
The reason why the GMR of the giant magnetoresistance effect element having the CPP structure of the present invention is much larger than the GMR of the giant magnetoresistance effect element having the conventional spin-valve CPP structure is Co ₂ Fe _0.5 Cr _0.5. It was found that this was due to the high spin polarizability of the Al thin film 3.
Further, as described above, the reason why such a large GMR can be obtained is that the resistivity of the Co ₂ Fe _0.5 Cr _0.5 Al thin film used for the pinned layer and the free layer depends on the resistivity of the antiferromagnetic layer 13 using IrMn. It turned out that the fact that it is equivalent also contributes.

  As described above, the magnetic thin film according to the present invention and the magnetoresistive element and the magnetic device using the same can obtain large TMR and GMR in a low magnetic field at room temperature. It is suitable for use as a magnetic field detection device for various electronic devices and various industrial devices, and also for a magnetic field detection device of medical electronic devices.

FIG. 2 is a sectional view of the magnetic thin film according to the first embodiment of the present invention. FIG. 4 is a cross-sectional view of a modification of the magnetic thin film according to the first embodiment of the present invention. The Co ₂ Fe _x Cr structure _1-x Al used in the magnetic thin film according to the first embodiment of the present invention is a diagram schematically illustrating. FIG. 6 is a diagram illustrating a cross section of a magnetoresistive element using a magnetic thin film according to a second embodiment of the present invention. FIG. 9 is a diagram showing a cross section of a modification of the magnetoresistive element using the magnetic thin film according to the second embodiment of the present invention. FIG. 9 is a diagram showing a cross section of a modification of the magnetoresistive element using the magnetic thin film according to the second embodiment of the present invention. FIG. 9 is a diagram illustrating a cross section of a magnetoresistive element using a magnetic thin film according to a third embodiment of the present invention. It is a figure showing the section of the modification of the magnetoresistive effect element using the magnetic thin film by a 3rd embodiment concerning the present invention. FIG. 4 is a diagram schematically illustrating resistance when an external magnetic field is applied to a magnetoresistive element using the magnetic thin film of the present invention. It is a diagram showing a result of measuring the X-ray diffraction of the Co ₂ Fe _0.5 Cr _0.5 Al thin film. It is a diagram showing a magnetization characteristic at room temperature of Co ₂ Fe _0.5 Cr _0.5 Al thin film. FIG. 6 is a diagram showing the magnetic field dependence of the resistance of the tunnel magnetoresistance effect element shown in FIG. 5. FIG. 5 is a diagram showing the magnetic field dependence of the resistance of the tunnel magnetoresistance effect element shown in FIG. 4.

Explanation of reference numerals

1,5: magnetic thin film 2: substrate _{3,16: Co 2 Fe x Cr 1} -x Al thin film 4: Buffer layer 10, 15, 20: tunnel magnetoresistance effect element 11: insulating layer 12 and 22: a ferromagnetic layer 13 : Antiferromagnetic layer 14: Electrode layer 21: Non-magnetic metal layer 30, 35: Giant magnetoresistive element

Claims (29)

A substrate and a Co ₂ Fe _x Cr _1-x Al thin film formed on the substrate,
A magnetic thin film, wherein the Co ₂ F _x Cr _1-x Al thin film has any one of L2 ₁ , B2, and A2 structures, and 0 ≦ x ≦ 1. The _{Co 2 Fe x Cr 1-x} Al thin film is characterized in that it is deposited without heating the substrate, a magnetic thin film according to claim 1. _3. The magnetic thin film according to claim 1, wherein the substrate is any one of thermally oxidized Si, glass, MgO single crystal, GaAs single crystal, and Al ₂ O ₃ single crystal. 4. Wherein the buffer layer between the _{Co 2 Fe x Cr 1-x} Al thin film and the substrate is disposed, the magnetic thin film according to claim 1.   The magnetic thin film according to claim 1, wherein the buffer layer is made of at least one of Al, Cu, Cr, Fe, Nb, Ni, Ta, and NiFe. In a tunnel magnetoresistive effect element having a plurality of ferromagnetic layers on a substrate, at least one of the ferromagnetic layers has a structure of Co ₂ Fe _x Cr _1-x Al (L 2 ₁ , B 2, A 2). Here, 0 ≦ x ≦ 1) a tunnel magnetoresistive element, which is made of a magnetic thin film. The ferromagnetic layer is composed of a fixed layer and a free layer, and the free layer has a structure of any one of L2 ₁ , B2, and A2 structures, where Co ₂ Fe _x Cr _1-x Al (where 0 ≦ x .Ltoreq.1) The tunnel magnetoresistance effect element according to claim 6, comprising a magnetic thin film. 8. The tunnel magnetoresistive element according to claim 6, wherein the Co ₂ F _x Cr _1-x Al thin film is formed without heating the substrate. The substrate and the _{Co 2 Fe x Cr 1-x} Al thin film (here, 0 ≦ x ≦ 1), characterized in that the buffer layer is disposed between the any of claims 6 to 8 3. The tunnel magnetoresistive element according to item 1. The substrate is thermally oxidized Si, glass, MgO single crystal, GaAs single crystal, characterized in that one or Al ₂ O ₃ single crystal, a tunnel magneto-resistance effect element according to claim 9.   The tunnel magnetoresistive element according to claim 9, wherein the buffer layer is made of at least one of Al, Cu, Cr, Fe, Nb, Ni, Ta, and NiFe. In a giant magnetoresistive element having a plurality of ferromagnetic layers on a substrate, at least one of the ferromagnetic layers has a structure of Co ₂ F _x Cr _1-x Al (any one of L2 ₁ , B2, and A2 structures) Here, 0 ≦ x ≦ 1) A giant magnetoresistive element, wherein the element is made of a magnetic thin film and has a structure in which a current flows in a direction perpendicular to the film surface. The ferromagnetic layer is composed of a fixed layer and a free layer, and the free layer has a structure of any one of L2 ₁ , B2, and A2 structures, where Co ₂ Fe _x Cr _1-x Al (where 0 ≦ x ≦ 1) The giant magnetoresistive element according to claim 12, which is made of a magnetic thin film. 14. The giant magnetoresistive element according to claim 12, wherein the Co ₂ F _x Cr _1-x Al thin film is formed without heating the substrate. Said substrate and said _{Co 2 Fe x Cr 1-x} Al ( wherein, 0 ≦ x ≦ 1), characterized in that the buffer layer is disposed between the thin film, any one of claims 12 to 14 The giant magnetoresistive element described in 1. The substrate is thermally oxidized Si, glass, MgO single crystal, wherein the GaAs single crystal, which is one or Al ₂ O ₃ single crystal, giant magnetoresistance according to any one of claims 12 to 15 Resistance effect element.   The giant magnetoresistive element according to claim 15, wherein the buffer layer is made of at least one of Al, Cu, Cr, Fe, Nb, Ni, Ta, and NiFe. A Co ₂ F _x Cr _1-x Al (here, 0 ≦ x ≦ 1) magnetic thin film having any one of L2 ₁ , B2, and A2 structures is formed on a substrate; Magnetic device. 19. A tunnel magnetoresistive element or a giant magnetoresistive element in which a free layer is made of the Co ₂ Fe _x Cr _1-x Al (here, 0 ≦ x ≦ 1) magnetic thin film. A magnetic device according to claim 1.   20. The magnetic device according to claim 18, wherein a tunnel magnetoresistive element or a giant magnetoresistive element manufactured without heating the substrate is used. A tunnel magnetoresistive element or a giant magnetoresistive element in which a buffer layer is disposed between the substrate and the Co ₂ Fe _x Cr _1-x Al (here, 0 ≦ x ≦ 1) thin film is used. The magnetic device according to claim 18, wherein: The substrate uses a tunnel magnetoresistive element or a giant magnetoresistive element, which is any one of thermally oxidized Si, glass, MgO single crystal, GaAs single crystal, and Al ₂ O ₃ single crystal. The magnetic device according to any one of claims 18 to 21.   5. The device according to claim 2, wherein the buffer layer comprises a tunnel magnetoresistive element or a giant magnetoresistive element made of at least one of Al, Cu, Cr, Fe, Nb, Ni, Ta, and NiFe. 22. The magnetic device according to 21. A Co ₂ F _x Cr _1-x Al (here, 0 ≦ x ≦ 1) magnetic thin film having any one of L2 ₁ , B2, and A2 structures is formed on a substrate; Magnetic head and magnetic recording device. 25. The free layer is made of a tunnel magnetoresistive element or a giant magnetoresistive element made of the Co ₂ Fe _x Cr _1-x Al (here, 0 ≦ x ≦ 1) magnetic thin film. 3. The magnetic head and magnetic recording device according to claim 1.   26. The magnetic head and magnetic recording apparatus according to claim 24, wherein a tunnel magnetoresistive element or a giant magnetoresistive element manufactured without heating the substrate is used. A tunnel magnetoresistive element or a giant magnetoresistive element in which a buffer layer is disposed between the substrate and the Co ₂ Fe _x Cr _1-x Al (here, 0 ≦ x ≦ 1) thin film is used. The magnetic head and the magnetic recording device according to claim 24, wherein: The substrate uses a tunnel magnetoresistive element or a giant magnetoresistive element, which is any one of thermally oxidized Si, glass, MgO single crystal, GaAs single crystal, and Al ₂ O ₃ single crystal. A magnetic head and a magnetic recording apparatus according to any one of claims 24 to 27.   5. The device according to claim 2, wherein the buffer layer comprises a tunnel magnetoresistive element or a giant magnetoresistive element made of at least one of Al, Cu, Cr, Fe, Nb, Ni, Ta, and NiFe. 28. The magnetic head and magnetic recording device according to 27.

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