JP2002208744A - Magnetoresistive element, magnetic head, and magnetic recording / reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a practical magnetoresistive element having an appropriate resistance value, capable of increasing sensitivity, and having a small number of magnetic layers to be controlled, and a magnetic head using the same. And a magnetic reproducing apparatus. SOLUTION: In a magnetoresistive element in which a sense current flows in a direction perpendicular to a film surface, a resistance adjusting layer is provided on at least one of a pinned layer, a free layer and a non-magnetic intermediate layer. The resistance adjusting layer contains oxide, nitride, fluoride, carbide, or boride as a main component, and may be a continuous film or provided with pinholes. To provide a practical magnetoresistive element having an appropriate resistance value, capable of achieving high sensitivity, and having a small number of magnetic layers to be controlled, while effectively utilizing the spin-dependent scattering effect. Can be.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive element, a magnetic head, and a magnetic reproducing apparatus, and more particularly, to a magnetoresistive element using a spin valve film in which a sense current flows perpendicular to a thin film surface. The present invention also relates to a magnetic head and a magnetic reproducing device equipped with the magnetoresistive element.

[0002]

2. Description of the Related Art In a certain type of ferromagnetic material, a phenomenon in which the electric resistance changes according to the strength of an external magnetic field is known, and this phenomenon is called the "magnetoresistive effect". This effect can be used for detecting an external magnetic field, and such a magnetic field detecting element is called a “magnetoresistive element (hereinafter, referred to as an MR element)”.

[0003] Such an MR element is industrially used for reading information stored in a magnetic recording medium in a magnetic recording and reproducing apparatus such as a hard disk or a magnetic tape (IEEE MAG-7, 150 ( 1971)), such a magnetic head is called an "MR head".

[0004] In recent years, magnetic recording / reproducing devices using these MR elements, particularly hard disk devices, have been increasing their magnetic recording densities.
The size of one bit has been reduced, and the amount of magnetic flux leakage from the bit has been increasingly reduced. For this reason, high sensitivity and high S /
Making an N-ratio MR element has become indispensable for reading information written on a magnetic medium, and is an important basic technology for improving the recording density.

Here, "high sensitivity" means a unit magnetic field (Oe).
This means that the resistance change (Ω) per hit is large,
An MR element having a larger MR change amount and having better soft magnetic characteristics has higher sensitivity. In order to realize a high S / N ratio, it is important to reduce thermal noise as much as possible. For this reason, it is not preferable that the element resistance itself be too large. When used as a reading sensor for a hard disk, in order to realize a good S / N ratio, it is desired that the element resistance be about 5Ω to 30Ω. It is rare.

[0006] Against this background, MR elements used in hard disk MR heads today have large M elements.
Spin valve (spin-valv) that can obtain R change rate
e) It is common to use membranes.

FIG. 25 is a conceptual diagram illustrating a schematic sectional structure of a spin valve film. The spin valve film 100 has a configuration in which a ferromagnetic layer F, a nonmagnetic layer S, a ferromagnetic layer P, and an antiferromagnetic layer A are stacked in this order. With the non-magnetic layer S interposed,
Of the two ferromagnetic layers F and P in a magnetically non-coupled state, one of the ferromagnetic layers P has its magnetization fixed by an exchange bias or the like using an antiferromagnetic material A, and the other has a strong magnetic strength. The magnetic layer F can be easily rotated by an external magnetic field (such as a signal magnetic field). Then, only the magnetization of the ferromagnetic layer F is rotated by an external magnetic field, and the relative angle between the magnetization directions of the two ferromagnetic layers P and F is changed, so that a large magnetoresistance effect can be obtained (Phys. Rev. B., Vol. 45, 806 (1992),
J. Appl. Phys. Vol. 69, 4774 (1991), etc.).

Here, the ferromagnetic layer F is a “free layer”,
It is called "magnetic field sensitive layer" or "magnetization free layer"
The ferromagnetic layer P may be referred to as a “pinned layer” or a “magnetization pinned layer”, and the non-magnetic layer S may be referred to as a “spacer layer”, a “non-magnetic intermediate layer” or an “intermediate layer”. Many.

The spin-valve film can rotate the magnetization of the free layer, that is, the ferromagnetic layer F even in a low magnetic field, so that the sensitivity can be increased and is suitable for an MR element for an MR head.

For such a spin valve element,
"Sense current" to detect change in resistance due to magnetic field
Need to be shed.

FIG. 26 is a conceptual diagram showing a generally used current supply system. That is, at present, as shown in the figure, a method of providing electrodes EL, EL at both ends of a spin valve element, flowing a sense current I parallel to the film surface, and measuring the resistance in the film surface parallel direction is generally used. I have. This method is generally called a “CIP (current-in-plane)” method.

In the case of the CIP method, the MR change rate is 1
It is possible to obtain a value of about 0 to 20%. Further, in a shield type MR head generally used at present, the spin valve element is used in a substantially square shape, so that the resistance of the MR element is substantially equal to the sheet electric resistance of the MR film. For this reason, in the case of the CIP type spin valve film, it is possible to obtain good S / N characteristics by setting the sheet electric resistance to 5 to 30Ω. This can be achieved relatively easily by reducing the thickness of the entire spin valve film. Due to these advantages, at present, the spin valve film of the CIP method is used for MR head MR heads.
It is generally used as an element.

However, in order to realize information reproduction at a high recording density exceeding 100 Gbit / inch ² , it is expected that a value exceeding 30% is required as the MR change rate. On the other hand, it is difficult for the conventional spin valve film to obtain an MR change rate exceeding 20%. Therefore, how to increase the MR ratio is a major technical issue for further improving the recording density.

From such a viewpoint, in order to increase the MR ratio, in the CIP-SV film, the “electron reflection layer” made of any one of oxide, nitride, fluoride and boride is contained in the pin layer and the free layer. Has been proposed.

FIG. 27 is a conceptual diagram showing a sectional structure of such a spin valve film. That is, in the configuration shown in FIG.
R has been inserted. In the spin valve film, when electron scattering occurs at the interface between the layers, the apparent mean free path decreases, and the MR change rate decreases. On the other hand, by providing the electron reflection layer ER and reflecting the electrons, the apparent mean free path of the electrons can be increased, and a large MR ratio can be obtained.

In this configuration, the probability of electrons passing through the magnetic / non-magnetic interface is increased by reflecting the electrons, so that the same effect as in the case of the artificial lattice film can be obtained. And the MR change rate increases.

However, even in this configuration, since not all electrons pass through the magnetic / nonmagnetic interface, there is a limit to the increase in the MR ratio. For this reason, even in the CIP-SV film into which the electron reflection layer is inserted as described above, a large MR change rate exceeding 20% and 5 to 30 Ω
It is practically difficult to realize a practical resistance change amount.

On the other hand, as a method of obtaining a large MR exceeding 30%, an artificial lattice in which a magnetic material and a non-magnetic pair are stacked is used in a direction perpendicular to the film surface (current perpendicular to the film surface).
A magnetoresistive element of a type in which a sense current flows through a lane (CPP) (hereinafter, CPP-artificial lattice) has been proposed.

FIG. 28 is a conceptual diagram showing a sectional structure of a CPP-artificial lattice element. In this type of magnetoresistive element, electrodes EL are provided above and below an artificial lattice SL in which ferromagnetic layers and nonmagnetic layers are alternately stacked, and a sense current I flows in a direction perpendicular to the film surface. In this configuration,
Since the probability that the current I crosses the interface between the magnetic layer and the non-magnetic layer increases, a good interface effect can be obtained, and a large M
It is known that an R change rate can be obtained.

However, in such a CPP artificial lattice type film, it is necessary to measure the electric resistance in the direction perpendicular to the film surface of the artificial lattice SL having a laminated structure of extremely thin metal films. However, this resistance value is generally very small. Therefore, in the CPP artificial lattice, it is an important technical problem to increase the resistance value as much as possible.
Conventionally, in order to increase this value, it is necessary to reduce the bonding area between the artificial lattice SL and the electrode EL as much as possible, increase the number of times of laminating the artificial lattice SL, and increase the total film thickness. . For example, the shape of the element is 0.1 μm × 0.
When patterned to 1 μm, Co2nm and Cu2n
If m and m are alternately laminated ten times, the total film thickness becomes 20 nm, and a resistance value of about 1Ω can be obtained. However, this still cannot be said to be a sufficiently large resistance value, and it is necessary to further increase the number of layers.

For the above reasons, in order to obtain a sufficient head output with a CPP artificial lattice type film and to use it as a good read sensor for a hard disk, it is necessary to use an artificial lattice type rather than a spin valve type. From the point of view, it turns out that it is essential.

On the other hand, when the MR element is used in an MR head, the magnetization of the magnetic layer is controlled so that the external magnetic field can be measured efficiently, and at the same time, Barkhausen noise and the like are not generated. It is necessary to make each magnetic layer a single magnetic domain. However, as described above, in the CPP-MR element, it is necessary to alternately laminate magnetic layers and non-magnetic layers many times in order to increase the resistance value. It is technically very difficult to perform the control.

When an MR element is used in an MR head, the magnetization rotates with high sensitivity to a small signal magnetic field,
It is necessary to obtain a large MR change rate. For this purpose, it is necessary to improve the signal magnetic flux density in the sensing portion so that a larger amount of magnetization rotation can be obtained even with the same magnetic flux density. Therefore, it is necessary to reduce the total Mst (magnetization × film thickness) of the layer whose magnetization is rotated by the external magnetic field. However, in the CPP-MR element, it is necessary to alternately laminate the magnetic layer and the non-magnetic layer many times in order to increase the resistance value, thereby increasing the Mst and improving the sensitivity to the signal magnetic flux. It has become difficult.

For this reason, a CPP artificial lattice type film can be expected to have an MR change rate exceeding 30%, but it is difficult to increase the sensitivity for use as an MR sensor for a magnetic head, and it is practically impossible. Has become.

On the other hand, FeMn / NiFe / Cu / NiF
e, It is conceivable to adopt the CPP method in a spin valve structure using FeMn / CoFe / Cu / CoFe or the like.

FIG. 29 is a conceptual diagram showing a sectional configuration of the CPP-SV element. However, in such a CPP-SV configuration, in order to increase the resistance value, it is necessary to increase the thickness of the magnetic layer to about 20 nm. Even in this case, the resistance change rate is about 30% at 4.2K. At room temperature, it is expected that only about 15% of the resistance change rate will be obtained at room temperature.

That is, in the CPP type spin valve film, an MR ratio of only about 15% can be obtained, and the Mst of the free layer has to be increased. Therefore, high sensitivity is required for use as an MR sensor for a head. Therefore, it is difficult to use them substantially.

[0028]

As described above,
CIP type spin valve film, CPP type artificial lattice,
Various systems such as a CPP type spin valve have been proposed. However, the magnetic recording density is currently increasing at an annual rate of 60% or more, and further increase in output is required in the future. However, at present, 100 Gbit / inch ²
It is difficult to realize a spin-valve film having an appropriate resistance value, a large MR change amount, and a magnetically high sensitivity, which can be used at a high recording density exceeding the above.

The present invention has been made based on the recognition of such problems, and it is an object of the present invention to provide a device having an appropriate resistance value while effectively utilizing the spin-dependent scattering effect, and achieving high sensitivity. Possible and with a small number of magnetic layers to be controlled,
An object of the present invention is to provide a practical magnetoresistive element, a magnetic head using the same, and a magnetic recording / reproducing apparatus.

[0030]

In order to achieve the above object, a magnetoresistive effect element according to a first aspect of the present invention has a magnetization fixed layer having a ferromagnetic film whose magnetization direction is substantially fixed to one side. A magneto-resistance effect film comprising: a magnetization free layer having a ferromagnetic film whose magnetization direction changes according to an external magnetic field; and a non-magnetic intermediate layer provided between the magnetization free layer and the magnetization fixed layer. And a pair of electrodes electrically connected to the magnetoresistive film to pass a current in a direction perpendicular to the film surface of the magnetoresistive film, an oxide, or a nitride,
Alternatively, a resistance adjusting layer mainly containing fluoride, carbide, or boride is provided.

The magnetoresistive element according to the second aspect of the present invention has a magnetization fixed layer having a ferromagnetic film having a magnetization direction substantially fixed to one side, and a magnetization direction corresponding to an external magnetic field. A magnetoresistive film having a magnetization free layer having a variable ferromagnetic film, a non-magnetic intermediate layer provided between the magnetization free layer and the magnetization pinned layer, and a film surface of the magnetoresistive film. A pair of electrodes electrically connected to the magnetoresistive film for applying a current in a direction perpendicular to the magnetoresistive film, and a resistance adjusting layer for limiting a passing amount of a sense current passing through the magnetoresistive film. A magnetoresistive effect element characterized in that:

The resistance adjusting layer may have a pinhole with an opening ratio of 50% or less in area ratio.

The resistance adjusting layer may be composed of two or more metal elements.

The resistance adjusting layer may be formed inside the magnetization free layer or on a side of the magnetization free layer opposite to the side on which the nonmagnetic intermediate layer is formed.

The resistance adjusting layer may be formed in the non-magnetic intermediate layer or at the interface.

The resistance adjusting layer may be formed in the film of the magnetization fixed layer or on the opposite side of the fixed layer from the side on which the nonmagnetic intermediate layer is formed.

The resistance adjusting layer is made of B, Si, G
e, Ta, W, Nb, Al, Mo, P, V, As, S
b, Zr, Ti, Zn, Pb, Th, Be, Cd, S
c, La, Y, Pr, Cr, Sn, Ga, Cu, In,
Rh, Pd, Mg, Li, Ba, Ca, Sr, Mn, F
At least one oxide, nitride, fluoride, carbide, or boride selected from e, Co, Ni, and Rb may be the main component.

The resistance adjusting layer is formed on the side of the magnetization free layer opposite to the side on which the non-magnetic intermediate layer is provided, in the layer of the non-magnetic intermediate layer, or at the interface.
Ag, Ru, Ir, Re, Rh, Pt, Pd, Al, O
At least one metal of s may be included.

The resistance adjusting layer is formed on the side of the magnetization free layer opposite to the side on which the nonmagnetic intermediate layer is provided, in the layer of the nonmagnetic intermediate layer or at the interface, and contains Cu as a main component. A first region, B, Fe, Mo, Pb, Ta, Cr,
An oxide containing at least one selected from V, Si, Sb, and Ge, or a nitride, or a fluoride, or a carbide, or a second region containing boride as a main component. good.

The resistance adjusting layer is formed on the side of the magnetization free layer opposite to the side on which the nonmagnetic intermediate layer is provided, in the nonmagnetic intermediate layer or at the interface, and contains Au as a main component. , A first region, B, Fe, Ge, Mo, P,
It may be configured to include an oxide containing at least one selected from Rh, Si, W, and Cr, or a nitride, a fluoride, a carbide, or a second region containing boride as a main component. .

The resistance adjusting layer is formed on the side of the magnetization free layer opposite to the side on which the nonmagnetic intermediate layer is provided, in the nonmagnetic intermediate layer or at the interface, and contains Ag as a main component. And the first region of Be, Co, Cr, Fe, M
an oxide containing at least one selected from o, Pb, Si, Ta, V, W, Ge, Sn, Al, Rh, or a nitride, a fluoride, a carbide, or a boride as a main component. May be provided.

Further, the magnetoresistive element according to the third aspect of the present invention has a magnetization fixed layer having a ferromagnetic film whose magnetization direction is substantially fixed to one side, and a magnetization direction corresponding to an external magnetic field. A magnetoresistive film having a magnetization free layer having a variable ferromagnetic film, a non-magnetic intermediate layer provided between the magnetization free layer and the magnetization pinned layer, and a film surface of the magnetoresistive film. A pair of electrodes electrically connected to the magnetoresistive film for applying a current in a direction perpendicular thereto, and on a surface of the magnetization free layer opposite to a side on which the nonmagnetic intermediate layer is provided, or B, Si, Ge, W, Nb, Mo, P, V, S
b, Zr, Ti, Zn, Pb, Cr, Sn, Ga, F
e, a region containing at least one selected from Co and mainly containing a crystalline oxide.

The thickness of the resistance adjusting layer may be 0.5 to 5 nm.

In addition, the resistance adjusting layer is 2% to 30%.
May be included.

The average diameter of the holes in the metal phase is as follows:
The sum of the thicknesses of the magnetization free layer, the nonmagnetic intermediate layer, and the magnetization fixed layer may be 5% to 100%.

The average spacing of the holes in the metal phase is 1
It may be 0 to 100 nm.

Further, a magnetic head according to a fourth aspect of the present invention is provided with any one of the above-described magnetoresistive elements.

A magnetic reproducing apparatus according to a fifth aspect of the present invention includes the magnetic head described above, and is capable of reading magnetic information stored on a magnetic recording medium.

[0049]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a conceptual diagram showing a sectional structure of a magnetoresistive element according to a first embodiment of the present invention. That is, the magnetoresistance effect element 10A of the present invention
Are provided on an anti-ferromagnetic layer A, a first substrate
, A non-magnetic intermediate layer S, and a second magnetic layer F in this order. The resistance adjustment layer R1 is inserted in the first magnetic layer P, and the resistance adjustment layer R2 is inserted in the second magnetic layer F. Note that the antiferromagnetic layer A, the first magnetic layer P, the non-magnetic intermediate layer S, and the second magnetic layer F constitute a magnetoresistive film.

Further, an electrode layer EL is provided above and below the laminated structure, and is characterized in that a sense current I flows in a direction perpendicular to the film surface.

In the present embodiment, the first magnetic layer P
Act as a “pinned layer” whose magnetization is fixed by the unidirectional anisotropy of the antiferromagnetic layer A. Further, the second magnetic layer F acts as a “magnetic field sensing layer” or a “free layer” that is magnetized and rotated by an external magnetic field (for example, a signal magnetic field) generated from a magnetic recording medium (not shown) or the like.

In the first magnetic layer P and the second magnetic layer F, resistance adjustment layers R1 and R2 are inserted respectively, and the ferromagnetic layer FM is inserted.
/ Resistance adjustment layer R1 or resistance adjustment layer R2 / ferromagnetic layer F
M has a laminated structure. In this structure, the ferromagnetic layers on both sides of the resistance adjusting layers R1 and R2 are in ferromagnetic coupling, and the magnetization thereof behaves substantially integrally. That is, the magnetizations of the respective ferromagnetic layers included in the ferromagnetic layer / resistance adjusting layer / ferromagnetic layer laminated structure are all substantially in parallel, and the pinned layer (first layer)
In the magnetic layer P), the magnetization is fixed in almost the same direction, and in the free layer (the second magnetic layer F), the magnetization direction is almost the same with respect to the external magnetic field.

In this embodiment, the current I is applied to the upper electrode E
L flows toward the lower electrode EL, but the resistance adjustment layer R
1, R2 is for flowing a current in the film thickness direction and reducing the amount of the current, and the resistance of the magnetoresistive element can be increased by inserting a resistance adjusting layer. That is, the resistance adjusting layers R1 and R2 are “filter layers” that limit the amount of the sense current I passed, or “current constriction layers” that transmit a part of the conduction electrons constituting the sense current I, or
It functions as a "barrier layer" for reducing the amount of the sense current I. The configuration and operation of a specific example of the resistance adjusting layer will be described with reference to FIG. The resistance adjustment layer R of this specific example has a configuration in which a pinhole H is formed in an insulator layer. When this resistance adjusting layer R is sandwiched between the films 20 and 21 constituting the magnetoresistive effect film, and the electrodes EL1 and EL2 are connected to these films, respectively, and a current flows perpendicularly to the film surface, the current becomes as shown in FIG. As shown by the broken line, since the current flows through the pinhole H, the amount of current is reduced, and the resistance is increased. The configuration and operation of the resistance adjusting layer are not limited to this, as described later.

Further, a part of the reduced current I flows while being repeatedly reflected between the two resistance adjusting layers R1 and R2. However, the amount of current flowing while repeating reflection is not so large in the sense current as a whole. However, this reduces the probability of electrons passing through the CPP spin-valve structure without reflection, thus further increasing the electrical resistance. These resistance adjusting layers have a morphologically different configuration from the electron reflection layer of the CIP type spin valve element.

In the CPP spin-valve film, the effect of electron scattering at the interface between the ferromagnetic layer and the non-magnetic layer, that is, the interface resistance has a large spin dependency and the CPP-M
It plays the role of increasing R. The interface resistance is
They tend to have relatively large values. These features are similar to the operation in the CPP artificial lattice described above with reference to FIG.

Therefore, by providing the resistance adjusting layer,
The resistance value in the direction perpendicular to the film surface can be increased. As a result, according to the present invention, more interface resistance can be used, and it is possible to realize a CPP-SV having a higher resistance and a higher MR ratio than a conventional CPP spin valve film. Become.

In this embodiment, since the current I is of the CPP type in which the current I flows in the direction perpendicular to the film surface, all the current I must cross the ferromagnetic layer / non-magnetic layer interface. become. As a result, it is possible to very effectively use the interface effect that could not be effectively used in the case of the CIP method. For this reason, the effect of increasing the MR change rate, which has not been obtained much with the CIP configuration, can be obtained extremely significantly.

With the above effects, it is possible to provide a CPP spin-valve element having a moderate resistance value, which makes good use of the interface resistance while having a spin-valve configuration.

In the present embodiment, the pinned layers P,
Since the magnetization of the free layer F operates integrally, the magnetization can be controlled only by the pinning of the magnetization of the pinned layer P and the magnetization of one free layer F. When used as a reading sensor such as a magnetic head, It is possible to realize a magnetic head in which Barkhausen noise is suppressed.

In this embodiment, the pin layers P,
It is possible to obtain a good resistance value and MR ratio while keeping the total thickness of the free layer F thin. That is, in the present configuration, as compared with the conventional simple CPP spin valve configuration, the simple transmission probability of electrons is reduced, the resistance value is increased, and the interface resistance can be sufficiently used. Even in a structure in which the total Mst of the layer P and the free layer F is small, it is possible to obtain a sufficient resistance value and MR change rate.

Specifically, in the conventional configuration, the thickness of the magnetic material of the pinned layer P and the free layer F is required to be about 20 nm, but according to the present embodiment, the total thickness of the magnetic layer is 5n.
Even below m, sufficient characteristics can be obtained. Thereby, Mst of the free layer F can be kept at a small value, and a highly sensitive spin valve element can be realized. Further, since Mst of the pinned layer P can be reduced, the magnetization pinning characteristics of the antiferromagnetic layer A can be improved, and the reliability as a device can be improved.

The resistance adjusting layers R1 and R2 in the present embodiment
Bi (bismuth), Sb (antimony), C
A semimetal such as (carbon) or a so-called zero-gap semiconductor such as ZnSe (zinc selenide) can be used. In these materials, unlike an insulator, conduction electrons exist, but since the density is very small, the potential felt by the conduction electrons is very small. Specifically, a metal such as Cu (copper) has a Fermi potential of about 7 eV, whereas a semimetal has a small Fermi potential of 1 eV or less.

Therefore, the resistance adjusting layers R 1, R 2 made of a semi-metal or a zero-gap semiconductor are provided in the metal layer that becomes a ferromagnetic material.
2, a large potential step occurs as illustrated in FIG. 2, and the transmission of conduction electrons is restricted. FIG. 2A shows the case where the magnetization of the pinned layer P and the free layer F are parallel, and FIG. 2B shows the case where the potential felt by the electrons is up-spin and down-spin when anti-parallel. It is the graph illustrated about the case.

In the structure of the present invention, the resistance adjusting layer R
1. Since conduction electrons are also present in R2, conduction by conduction electrons is sufficiently larger than the transmission probability of electrons by tunneling, and normal conduction dominate the overall resistance value. . Therefore, it is possible to reduce the resistance as compared with the case of the ferromagnetic tunnel junction, and it is possible to obtain a good element resistance in a minute junction.

It is desirable that the value of the Fermi potential of these materials be in the range of 1 eV to 0 eV. More preferably, the range of 0.5 eV to 0 eV is suitable. First, in these materials, the smaller the value of the Fermi potential, the more it is possible to make a step in the potential felt by electrons, so that the electron transmission probability can be reduced. Because it becomes. Further, since the number of conduction electrons in the semimetal is also reduced, the probability of electron transmission can be extremely reduced. For 0.5 eV, electron number than the noble metal such as Cu conduction electron number becomes about 3.5 × 10 ^{2 0} pieces since the 2 orders of magnitude smaller value may desire a large resistance increase. Therefore, it is desirable that the value of Fermi potential in these materials be 0.5 eV or less. However, if it is 1 eV or less, the number of conduction electrons is about 4.6 × 10 ²¹ , and the number of electrons is about one digit smaller than that of a noble metal such as Cu. Can be.

Further, the resistance adjusting layer R according to the present embodiment is
Au (gold), Ag (silver), or an alloy thereof can also be used as the material of 1, R2. However, in this case, it is difficult to form a very large potential step, so that it is not easy to obtain a large increase in resistance.

The resistance adjusting layer R according to the present embodiment is
1, an insulator having a relatively low potential barrier height can be used as R2. FIG. 3 is a potential diagram corresponding to this configuration. That is, FIG.
FIG. 3B shows that when the magnetizations of the pinned layer and the free layer are parallel,
Is a graph illustrating potentials felt by electrons in the case of up spin and the case of down spin in antiparallel cases, respectively.

In the case of this specific example, the transmission probability of electrons is determined by the tunneling probability of electrons in the resistance adjusting layers R1 and R2. Therefore, since the element resistance becomes too high when the barrier height is increased, the barrier height of the resistance adjusting layers R1 and R2 is desirably 0.1 eV or less.

On the other hand, the resistance adjusting layer R in the present embodiment
1, an insulator having a pinhole can be used as R2. In this case, the transmission probability of electrons is determined by the size and density of the pinhole. FIG.
Is a conceptual diagram illustrating a cross-sectional configuration of the specific example. As shown in the figure, a pinhole H can be appropriately provided in the resistance adjusting layers R1 and R2. Here, when the size of the pinhole H is set to be equal to or smaller than the mean free path of electrons, a larger resistance increasing effect can be obtained. The density of the pinholes H is preferably, for example, at least 10 or more pinholes formed in the film surface of the element from the viewpoint of reproducibility of element characteristics. However, conversely, only one pinhole H may exist in the element. Further, the ratio between the total area of the pinholes H and the film area of the element can be determined as appropriate, but preferably 50% or less is ideal for increasing the element resistance.

In the specific example of FIG. 4, the transmission probability of the electrons is determined by the electric conduction through the pinhole H. Therefore, as a material constituting the resistance adjusting layers R1 and R2, an insulator having a large barrier height, for example, Al (aluminum)
Oxide, Si (silicon) oxide, or the like can also be used. However, a material having a low barrier height such as Co (cobalt) oxide, Ni (nickel) oxide, or Cu (copper) oxide can also be used. Even in that case, the electric conduction is mainly controlled by the pinhole H.

The resistance adjusting layer R in the specific example of FIG.
1, the thickness of R2 can also be determined as appropriate. However, in order to surely and easily form the pinhole H, 0.5n
It is desirable to set in the range of m to 10 nm.

The position of the pinhole H in each of the resistance adjusting layers R1 and R2 of the pinned layer P and the free layer F does not need to be particularly controlled. In this case, electrical conduction through the randomly formed pinholes H is obtained.

As a method for forming the resistance adjusting layers R1 and R2 having such pinholes H, for example, an ultra-thin Al layer is formed by a method such as sputtering, and then exposed to an oxygen atmosphere for a short time and then spontaneously oxidized. Can be formed. Alternatively, an extremely thin layer of Al or the like can be formed by a method of applying energy such as exposure to oxygen plasma, irradiation of oxygen ions, or irradiation of oxygen radicals.

As the oxidized layer, for example, Al—Co
As described above, an Al-Co granular (granular) film is formed by simultaneously forming a material that is relatively easily oxidized and a material that is not easily oxidized, and only Al is selected by exposing it to oxygen. It can also be formed by oxidation.

In addition, by forming a film in an oxygen atmosphere, an oxide layer having a pinhole H can be formed.

Another method of forming the resistance adjusting layers R1 and R2 having such a pinhole H is, for example, as follows.
Fine processing using an AFM (atomic force microscope) or the like, or regularly arranged pinholes H can be formed by self-organization. In the case of fine processing using AFM or the like, for example, a continuous film of AlOx (aluminum oxide) is formed, and a hole can be formed in the AlOx. When regularly arranged pinholes are formed by self-organization, for example, a continuous film of AlOx is formed, and a resist on which pinholes are formed by self-organization is applied on the AlOx. The AlOx in the pinhole portion can be removed by milling or RIE. Also, an insulator having pinholes H aligned by self-organization can be directly formed.

The pinhole H is controlled in this manner.
Is formed, the positional relationship of the pinholes H in the two resistance adjusting layers R1 and R2 becomes important. That is,
As illustrated in FIG. 5A, the upper and lower resistance adjusting layers R1,
The position of the pinhole H may be the same between R2. Further, as illustrated in FIG. 5B, the pinhole H may be provided so as to be displaced between the upper and lower resistance adjusting layers R1 and R2. FIG.
If the position is shifted as illustrated in (b), a more effective reduction in the amount of current can be obtained, and a higher-resistance CPP spin valve element can be realized.

When the pinhole H is formed by a controlled method, the relationship between the size of the pinhole H in the two resistance adjusting layers R1 and R2 can be adjusted.
That is, the size of the pinhole H may be the same between the upper and lower resistance adjustment layers R1 and R2, or may be different. Resistance adjustment layer R
1, the larger the size of the pinhole H of the resistance adjusting layer, into which electrons enter, is larger than the size of the pinhole, from which electrons exit, of the R2. Reduction can be obtained, and a higher-resistance CPP spin valve element can be formed.

Further, the resistance adjusting layers R1 and R2 in the laminated structure of the ferromagnetic layer / electron reflecting layer need not necessarily be constituted by only one layer, and as shown in FIG.
One or more resistance adjustment layers R1A and R1B or resistance adjustment layers R2A and R2B may be included. By inserting a plurality of resistance adjusting layers in this way, the probability of simple transmission of electrons can be further reduced, and a CPP-SV with higher resistance can be realized.

On the side of the free layer F, as shown in FIG. 7, the resistance adjusting layer R2 is not inserted into the ferromagnetic layer FM but is sandwiched between the nonmagnetic layers NM1 and NM2. It is also possible. By doing so, it is possible to minimize the influence of the resistance adjusting layer R2 on the magnetic characteristics of the free layer F, and it is easy to achieve compatibility with the soft magnetic characteristics.

The ferromagnetic layers included in the first and second magnetic layers P and F in the present embodiment described above include, for example, Co alone or Co such as a Co-based magnetic alloy. It can be made of a ferromagnetic material, a Ni-based alloy such as a NiFe alloy, or an Fe-based alloy.

Here, as the Fe-based alloy, Fe
It is desirable to use a material that can easily obtain soft magnetic characteristics, such as (iron), FeNi (iron nickel), FeCo (iron cobalt), FeSi (iron silicon), FeMo (iron molybdenum), and FeAl (iron aluminum).

Further, as the Co-based alloy, Fe (iron), Ni (nickel), Au (gold), Ag
(Silver), Cu (copper), Pd (palladium), Pt (platinum), Ir (iridium), Rh (rhodium), Ru
(Ruthenium), Os (osmium), and Hf (hafnium) may be an alloy to which one or more of them are added. The addition amount of these additional elements is 5 to 50.
Atomic%, preferably 8 to 20 atomic%.
It is desirable to be within the range. This is because if the addition amount is too small, the bulk effect does not sufficiently increase, while if the addition amount is too large, the interface effect may be greatly reduced. As an additive element, in order to obtain a large MR ratio, it is particularly desirable to use Fe.

The first and second embodiments of the present embodiment
The ferromagnetic layers included in the magnetic layers P and F may have a laminated structure of a ferromagnetic layer FM and a non-magnetic layer NM as illustrated in FIG. In the laminated structure of the ferromagnetic layer FM / nonmagnetic layer NM, the ferromagnetic layers FM sandwiching the nonmagnetic layer NM are in ferromagnetic coupling, and the magnetization is substantially parallel. They are aligned and have almost the same magnetization direction.

When the layered structure film as illustrated in FIG. 8 is used for the pinned layer P and the free layer F, electrons pass through a larger number of ferromagnetic / non-magnetic layer interfaces. CPP
The spin valve film has the effect of electron scattering at the interface between the ferromagnetic layer and the nonmagnetic layer, that is, the interface resistance has a large spin dependence, and has the effect of increasing CPP-MR. In this specific example, since more interface resistance can be used,
It is possible to obtain a larger resistance change rate. In addition,
In FIG. 8, a high conductive layer G having high electric conductivity is provided between the free layer F and the electrode EL.

The insertion of the resistance adjusting layers R1 and R2 is particularly
Although it is effective for increasing the resistance of the P spin bubble film, laminating the pinned layer P and the free layer F is particularly effective for increasing the MR ratio. Therefore, by combining these two, it is possible to obtain a CPP spin valve film having a particularly high resistance and a high MR ratio.

As the laminated film of the ferromagnetic material layer FM / nonmagnetic material layer NM in this specific example, it is desirable to obtain a large spin-dependent interface resistance at the interface between the magnetic material layer FM / nonmagnetic material layer NM. As a combination of such a ferromagnetic material and a non-magnetic material, the material of the ferromagnetic material layer FM is Fe
Non-magnetic layer N using base alloy, Co base alloy, Ni base alloy
It is desirable to use Cu, Ag, Au or an alloy thereof as the material of M.

Further, as the material of the nonmagnetic layer NM, in addition to these, Rh (rhodium), Ru (ruthenium), Mn (manganese), Cr (chromium), Re (rhenium), Os (osmium) It is also desirable to use a non-ferromagnetic metal such as Ir (iridium). In particular, it is desirable to use Mn or Re.

Among them, combinations having particularly large interface resistance include Fe-base alloy / Au and Fe-base alloy / A
g or an interface of an Fe-based alloy / Au-Ag alloy, a Co-based alloy / Cu, an interface of a Co-based alloy / Ag, a Co-based alloy / Au, or an interface of a Co-based alloy / Cu-Ag-Au alloy.

The thickness of the ferromagnetic layer FM included in the laminated structure of the ferromagnetic layer FM / non-magnetic layer NM increases the magnetic stability of the pinned layer P and increases the magnetic stability of the free layer F. In order to measure the sensitivity by reducing the Mst, it is desirable to make the thickness as thin as possible. The upper limit of the film thickness is desirably 2 nm or less in order to increase the number of interfaces.

On the other hand, the ferromagnetic layer FM /
The combination of the materials forming the laminated structure of the nonmagnetic layer NM is preferably a non-solid solution combination in order to obtain good interface resistance. That is, it is desirable that the materials forming the ferromagnetic layer FM and the nonmagnetic layer NM have a non-solid solution relationship with each other. However, it is not always necessary to limit the combination to a non-solid solution system according to the required level.

The ferromagnetic material layer FM /
The ferromagnetic layer FM in the laminated structure of the nonmagnetic layer NM is
It is not always necessary to be composed of one kind of material.
As exemplified in the above, a laminated film of two or more kinds of ferromagnetic materials may be used. That is, in the example shown in FIG. 9, the pinned layer P and the free layer F are formed by laminating a first ferromagnetic layer FM1, a second ferromagnetic layer FM2, and a third ferromagnetic layer FM3, respectively. Having a configuration. However, the type, number of layers, and stacking order of the ferromagnetic layers are not limited to those shown in FIG.

For example, in the pinned layer P, it is desirable to use an Fe / Au interface having a large interface resistance.
Since spin fluctuations are large, it is desirable to suppress spin fluctuations for use at room temperature. For this purpose, Fe / CoFe / Fe, Fe / Ni
It is desirable to have a laminated structure with a magnetic material having small spin fluctuation, such as Fe / Fe.

On the other hand, it is desirable to use the Fe / Au interface having a large interface resistance also in the free layer F.
It is difficult to obtain the necessary soft magnetic properties as a free layer only by using the material alone. Therefore, as the ferromagnetic layer, Fe / CoF
It is desirable to have a laminated structure with a magnetic material having excellent soft magnetic properties, such as e / Fe and Fe / NiFe / Fe.

Also, the ferromagnetic layer in the laminated structure of the ferromagnetic layer / resistance adjustment layer does not necessarily need to be made of one kind of material.

FIG. 10 is a conceptual diagram exemplifying a case where the ferromagnetic layers sandwiching the resistance adjusting layer are composed of two or more ferromagnetic layers. That is, in the specific example shown in the figure, the pinned layer P and the free layer F have a first ferromagnetic layer FM1 and a second ferromagnetic layer FM2, respectively.

For example, in the free layer F, it is desirable to use an Fe / Au interface having a large interface resistance.
It is difficult to obtain the necessary soft magnetic properties as a free layer only with e. On the other hand, by adding a magnetic layer made of a magnetic material having excellent soft magnetic properties such as CoFe and NiFe ferromagnetically coupled as the ferromagnetic layer, the soft magnetic properties can be improved. .

When the ferromagnetic layer FM in the laminated structure of the ferromagnetic layer FM / nonmagnetic layer NM contains Fe or an Fe-based alloy, the crystal structure is fcc (face cen).
(tered cubic) structure is desirable. This is A
When a metal having an fcc structure such as u, Ag, Cu or the like is laminated, a laminated structure having better crystallinity can be formed as a whole, and the soft magnetic characteristics can be improved and the spin can be improved. This is because effects such as reduction of fluctuation can be obtained. However, a bcc structure can also be used.

In particular, when two types of magnetic materials are combined as a ferromagnetic layer in a laminated structure of a ferromagnetic layer and a nonmagnetic layer, as shown in FIG. 11, a ferromagnetic layer FM (fcc ) And a ferromagnetic layer FM having a bcc structure
(Bcc) can also be combined. In such a combination, the ferromagnetic material FM (f
cc) and the ferromagnetic material FM (bcc) having the bcc structure have significantly different electronic states, Fermi surface shapes, distributions of state densities, and the like. It is possible to obtain a change rate. As shown, the crystal structure of the pinned layer P and the free layer F is such that the first magnetic layer P is a ferromagnetic layer having a bcc structure and the second magnetic layer F is a ferromagnetic layer having an fcc structure. Even with a different configuration, a large filter effect can be obtained.

In the present invention, the ferromagnetic layers need to be ferromagnetically coupled to each other in the laminated structure of the ferromagnetic layer / nonmagnetic layer constituting the pinned layer P and the free layer F. Therefore, it is necessary to form a good laminated structure. The magnetic properties of the pinned layer P and the free layer F can be improved by adjusting the crystal lattice constant in the laminated structure to an optimal value. For this reason, as illustrated in FIG. 12, the nonmagnetic layer NM is also, for example, the first nonmagnetic layer N
A stacked structure of M1 and the second nonmagnetic layer NM2 is preferable. For example, when the nonmagnetic layer NM has a laminated structure such as an Au layer / Cu layer / Au layer, a good lattice constant can be realized while realizing a large interface resistance, and good magnetic characteristics can be obtained. .

Further, the ferromagnetic layer FM included in the first and second magnetic layers P and F in the present invention has a ferromagnetic layer FM1 / ferromagnetic layer FM2 as illustrated in FIG.
And a laminated structure of the above. In the stacked structure of the ferromagnetic layers FM1 and FM2, the ferromagnetic layers are in ferromagnetic coupling with each other, the magnetizations are substantially aligned in parallel, and are substantially the same. It has a magnetization direction.

When such a laminated structure film is adopted for the pinned layer P and the free layer F, electrons pass through a larger number of ferromagnetic layer / ferromagnetic layer interfaces. The CPP spin-valve film has the effect of electron scattering at the ferromagnetic layer / ferromagnetic layer interface, that is, the interface resistance has a large spin dependency, and has the effect of increasing CPP-MR. In this specific example, since more interface resistance can be used, it is possible to obtain a higher resistance and a larger resistance change rate.

The insertion of the resistance adjusting layers R1 and R2 is particularly effective when the CP
Although it is effective for increasing the resistance of the P spin bubble film, laminating the pinned layer P and the free layer F is particularly effective for increasing the MR ratio. Therefore, by combining these two, it is possible to obtain a CPP spin valve film having a particularly high resistance and a high MR ratio.

In this example, it is possible to arrange a large number of ferromagnetic layers / ferromagnetic layers in the pinned layer P and the free layer F, so that more interface resistance can be utilized. Thus, a CPP-SV having a high resistance and a high MR change rate can be configured.

Since the magnetizations of the pinned layer P and the free layer F operate integrally, the magnetization can be controlled only by fixing the magnetization of the pinned layer P and controlling the magnetization of one free layer F. When used in a sensor, it is possible to realize a magnetic head in which Barkhausen noise is suppressed.

Each ferromagnetic layer constituting the laminated structure of ferromagnetic layer / ferromagnetic layer in this specific example is made of, for example, Co.
It can be composed of a single substance, a ferromagnetic material containing Co such as a Co-based magnetic alloy, a ferromagnetic material such as a NiFe alloy, or an Fe-based alloy.

Combinations having particularly large interface resistance include NiFe alloy / CoFe alloy and Fe-based alloy / NiF
It is desirable to use an e alloy or an Fe-based alloy / CoFe alloy.

It is desirable that the thickness of the ferromagnetic layer included in the ferromagnetic layer / ferromagnetic layer laminated structure be as small as possible in order to increase the number of interfaces without increasing the overall Mst. . In a combination in which the magnetism is maintained, the ferromagnetic layer can be composed of one atomic layer. Further, the upper limit of the film thickness is desirably 2 nm or less in order to increase the number of interfaces.

On the other hand, the thickness of the ferromagnetic layer included in the ferromagnetic layer / ferromagnetic layer laminated structure is desirably 1 nm or less in order to increase the number of interfaces as much as possible. As a lower limit, it is possible to generate an interface resistance even with a monoatomic layer.

The combination of materials for forming the ferromagnetic layer / ferromagnetic layer laminated structure is preferably a non-solid solution combination in order to obtain good interface resistance. However, it is not always necessary to limit the combination to the non-solid solution type, and the combination can be determined as appropriate.

FIG. 14 is a conceptual diagram showing another specific example when a plurality of ferromagnetic layers are provided. That is, in the example of FIG. 3, each of the pinned layer P and the free layer F is the first layer.
And a second ferromagnetic layer FM2, and a third ferromagnetic layer FM3 is provided adjacent to the electron reflection layers R1 and R2.

For example, in the free layer F, it is desirable to use an Fe / CoFe interface having a large interface resistance, but it is difficult to obtain soft magnetic characteristics required for the free layer only with Fe. For this reason, it is possible to improve the soft magnetic properties by adding a magnetic material having excellent soft magnetic properties, such as NiFe, which is ferromagnetically coupled, as the ferromagnetic layer FM3.

When the ferromagnetic layer in the ferromagnetic layer / ferromagnetic layer laminated structure contains Fe or an Fe-based alloy, it preferably has an fcc structure. This is because when a metal having an fcc structure such as CoFe or NiFe is laminated, it is possible to further stabilize the structure, to form a laminated structure having good crystallinity as a whole, to improve soft magnetic characteristics, and to improve spin fluctuation. This is because there is an effect such as a decrease in However, a bcc structure can also be used.

As a combination of two types of ferromagnetic layers, a ferromagnetic substance having an fcc structure and a ferromagnetic substance having a bcc structure can be used. As described above with reference to FIG. 11, in such a combination, the ferromagnetic material having the fcc structure and the ferromagnetic material having the bcc structure have significantly different electronic states, Fermi surface shapes, distributions of state densities, and the like. , It is possible to obtain a large resistance and a large MR change rate.

By the way, in the CPP-SV, when conduction electrons pass through the pinned layer P and the free layer F, they are scattered by electrons. Modulation of the band potential. For this reason, the wave vector of the electrons that can flow in the direction perpendicular to the film surface is restricted according to the modulation of the band potential. The wave number subject to this limitation depends on the period of the multilayer structure. Therefore, by changing the multilayer period in the pinned layer P and the free layer F, it is possible to greatly limit the wave number that can pass through both layers. Since the filter effect itself has a spin-dependent effect, it is possible to keep the spin dependence high while lowering the overall electron transmission probability. That is, by intentionally making the lamination cycles of the pinned layer P and the free layer F different, it is possible to realize a CPP-SV that can realize a higher MR ratio while further increasing the resistance.

On the other hand, the material of the nonmagnetic intermediate layer S is C
It is desirable to use a substance having a long mean free path of conduction electrons, such as u (copper), Au (gold), and Ag (silver). By using such a substance, electrons can be conducted ballistically between the first ferromagnetic layer P and the second ferromagnetic layer F, and more effectively due to the ferromagnetic material. The electron-dependent spin-dependent scattering effect.
This makes it possible to obtain a large MR change rate.
Further, the non-magnetic intermediate layer S can be made of an alloy of the above three elements. In this case, it is desirable to adjust the composition so that the crystal lattice constant in the laminated structure can be adjusted to an optimum value.

The non-magnetic intermediate layer S has a laminated structure of a non-magnetic layer S1 and a non-magnetic layer S2 in which materials such as Cu, Au and Ag are laminated as shown in the sectional structure of FIG. It is also possible. At this time, by appropriately setting the lamination period of the non-magnetic layer S1 / non-magnetic layer S2 and the lamination period of the pinned layer P or the free layer F,
It is possible to realize a CPP-SV that limits the wave vector of electrons that can flow through the entire CPP-SV in the direction perpendicular to the film surface, and that can realize a higher resistance and a higher MR ratio.

On the other hand, as the material of the antiferromagnetic layer A, it is desirable to use a metal antiferromagnetic material having excellent magnetization pinning characteristics. Specifically, PtMn, NiMn, FeMn, I
An antiferromagnetic material such as rMn can be used. It is desirable that the thickness of these layers be as small as possible in view of electrical characteristics. However, if the thickness is too small, the magnetization sticking characteristics deteriorate, so it is necessary to select a film thickness that does not decrease the blocking temperature. Therefore, it is desirable that the film thickness be 5 nm or more.

Further, in addition to the above structure, a so-called synthetic antiferromagnetic structure can be employed as illustrated in FIG. This is because, in one or both of the first magnetic layer P and the second magnetic layer F, a pair of ferromagnetic layers FM1 that are antiferromagnetically coupled to each other via the antiferromagnetic coupling layer AC. , FM2.
By adopting such a synthetic configuration,
In the pinned layer P, the apparent magnetization can be reduced to zero, and the pinned magnetization of the pinned layer P can be made more stable. In the free layer F,
By reducing the apparent magnetization, a more sensitive external magnetic field response can be obtained.

Further, in addition to the above configuration, it is also possible to adopt a so-called dual configuration in which two pin layers P are provided.

On the other hand, in the above specific example, the electrode EL
Although no special layer was disposed between the first electrode and the spin valve film, when an actual device was formed, as illustrated in FIG. It is desirable to form a base layer (buffer layer) B to improve smoothness and crystallinity. Further, it is desirable to arrange a layer C to be a protective layer between the upper electrode EL2 and the free layer F. As the underlayer B and the protective layer C, Ta (tantalum), Ti (titanium),
Materials with good wettability such as Cr (chromium), Cu, Au, A
It is desirable to use a material having a small electric resistance such as g and having a stable fcc structure, or a laminated structure thereof.

(Second Embodiment) Next, a second embodiment of the present invention will be described.

FIG. 18 is a conceptual diagram showing a sectional structure of a magnetoresistive element according to the second embodiment of the present invention. In this figure, the same elements as those described above with reference to FIGS. 1 to 17 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The magnetoresistance effect element of this embodiment is also laminated on a predetermined substrate in the order of an antiferromagnetic layer A, a first magnetic layer P, a non-magnetic intermediate layer S, and a second magnetic layer F. Sense current I
Is flowed in a direction perpendicular to the film surface. Note that the antiferromagnetic layer A, the first magnetic layer P, the non-magnetic intermediate layer S, and the second magnetic layer F constitute a magnetoresistive film.

In this embodiment, the resistance adjusting layer R is inserted in the non-magnetic intermediate layer S.

In this embodiment, the current I flows from the upper electrode EL2 toward the lower electrode EL1, but the amount of current is reduced by the resistance adjusting layer R. As a result, the probability of electrons passing through the CPP spin valve structure is reduced, so that the electrical resistance can be greatly increased as a whole.

In this embodiment, the transmission probability of electrons is reduced, so that the electric resistance can be largely increased as a whole. However, since the spin-dependent scattering effect itself is not impaired, the MR change rate is large. Can be kept.

With the above-described effects, it is possible to provide a CPP spin valve element having a moderate resistance value, which makes good use of the interface resistance while having a spin valve structure.

Also in this embodiment, since the magnetizations of the pinned layer P and the free layer F operate integrally, the magnetization can be controlled only by fixing the magnetization of the pinned layer P and controlling the magnetization of one free layer F. When used in a reading sensor such as a head, it is possible to realize a magnetic head in which Barkhausen noise is suppressed.

In this embodiment, the pinned layers P,
It is possible to obtain a good resistance value and MR ratio while keeping the total thickness of the free layer F thin. That is, in the present configuration, as compared with the conventional simple CPP spin valve configuration, the simple transmission probability of electrons is reduced, the resistance value is increased, and the interface resistance can be sufficiently used. Ms of total of layer P and free layer F
In a region where t is small, a sufficient resistance value and MR change rate can be obtained. Specifically, in the conventional configuration, the pin layer P,
Although the thickness of the magnetic material of the free layer F was required to be about 20 nm, this configuration makes it possible to obtain sufficient characteristics even when the total thickness of the magnetic layer is 5 nm or less. Thereby, Mst of the free layer F can be kept at a small value, and a highly sensitive spin valve element can be configured.

Further, since the Mst of the pinned layer P can be reduced, the pinning characteristics of the antiferromagnetic layer A can be improved, and the reliability as a device can be improved.

The material of the resistance adjusting layer R in this embodiment is also the same as that described in the first embodiment.
Semimetals such as Bi, Sb, and C, and so-called zero-gap semiconductors such as ZnSe can be used. In these materials, unlike the insulator, conduction electrons exist, but since the density is very small, the potential felt by the conduction electrons is very small. Specifically, as described above, a metal such as Cu has a Fermi potential of about 7 eV, whereas a metalloid has a small value of 1 eV or less.

For this reason, if a metalloid or a zero-gap semiconductor is sandwiched in the metal layer, a large potential step occurs, and the conduction electrons are reflected. In this configuration, since conduction electrons are also present in the resistance adjustment layer, conduction by conduction electrons is sufficiently larger than the transmission probability of electrons by tunneling, and normal conduction increases the overall resistance value. Dominates. For this reason, the resistance can be reduced as compared with the case of the ferromagnetic tunnel junction, and a good element resistance can be obtained in a minute junction.

It is desirable that the value of the Fermi potential of these materials be in the range of 1 eV to 0 eV. More preferably, the range of 0.5 eV to 0 eV is suitable. The reason for this is as described above with respect to the first embodiment.

As the material of the resistance adjusting layer R in the present embodiment, Au, Ag, or an alloy thereof can be used. However, in this case, it is difficult to form a very large potential step,
It is difficult to obtain a large increase in resistance.

In addition, as a material of the resistance adjusting layer R in the present embodiment, an insulator having a low potential barrier height can be used. In this case, the transmission probability of electrons is determined by the tunnel probability, so that when the barrier is high, the element resistance becomes too high. From this viewpoint, the barrier height is desirably 0.1 eV or less.

In addition, as the resistance adjusting layer R in the present embodiment, an insulator having a pinhole as described above with reference to FIGS. 4 to 6 can be used. In this case, the transmission probability of electrons is determined by the size and density of the pinhole. Here, by setting the pinhole size equal to or smaller than the mean free path of electrons, it is possible to obtain a greater effect of increasing the resistance. Regarding the pinhole density, it is desirable that at least about 10 pinholes are formed in the element area from the viewpoint of reproducibility of element characteristics. However, conversely, only one pinhole may exist in the device. The ratio between the total area of the pinholes and the element area is desirably 50% or less, which is ideal for increasing the element resistance.

In this case, since the transmission probability of the electrons is determined by the electric conduction through the pinhole, the insulator constituting the resistance adjusting layer R has a large barrier height, for example, an Al oxide Or Si oxide can be used. However, a material having a low barrier height such as a Co oxide, a Ni oxide, and a Cu oxide can also be used. Even in such cases, electrical conduction is dominated by the pinhole.

In addition, the thickness of the insulator layer in the present embodiment is 0.5 nm or more in order to easily form a pinhole.
It is desirable to set in the range of 10 nm.

As the method for forming the insulator layer having such a pinhole, the various methods described above with reference to the first embodiment can be used. That is, after forming an extremely thin layer of Al by a method such as sputtering, the layer can be exposed to an oxygen atmosphere for a short time and formed by natural oxidation. Alternatively, it can be formed by a method of applying energy such as exposure to oxygen plasma, irradiation of oxygen ions, irradiation of oxygen radicals, or the like. Further, as a layer to be oxidized, a material which is relatively easily oxidized such as Al-Au and a material which is hardly oxidized are simultaneously formed to form an Al layer.
It can also be formed by forming a granular film of Au and exposing it to oxygen to selectively oxidize only Al. Further, in addition to these, an oxide layer having a pinhole can be formed by forming a film in an oxygen atmosphere.

Further, as another method of forming the insulator layer having such pinholes, for example, fine processing using AFM or the like, or formation of regularly arranged pinholes by self-organization are known. Can also. These details are also as described above with respect to the first embodiment.

On the other hand, the resistance adjusting layer R in the present embodiment
Need not necessarily be composed of only one layer,
It may have a laminated structure of more than layers. The resistance adjusting layer R may include not only one layer but also a plurality of layers in the nonmagnetic intermediate layer S. By inserting a plurality of resistance adjusting layers R into the non-magnetic intermediate layer S in this manner, the probability of simple transmission of electrons can be further reduced, and a CPP-SV with higher resistance can be configured. .

Further, the configuration of the present embodiment can be combined with the various configurations described above as the first embodiment of the present invention. As a result, a CPP spin valve film having a higher resistance can be formed.

In the combination of the second embodiment and the first embodiment, when forming by controlling the positions of the pinholes, the relationship between the positions of the pinholes H in the respective resistance adjusting layers R, R1, R2 is determined. Becomes important. In other words, the position of the pinhole H may be the same between the respective resistance adjustment layers as illustrated in FIG. 19, while the position of the pinhole H may be the same as illustrated in FIG. It is also possible to provide the pinholes H so that the positions thereof are shifted between them.

As shown in FIG. 20, when the position of the pinhole H is shifted, the amount of current can be reduced more effectively, so that a CPP spin valve element with higher resistance can be formed. .

In the case where the positions of the pinholes H are controlled as described above, the respective resistance adjusting layers R, R
1. The relationship between the size of the pinhole H in R2 is also important. In this case, the size of the pinhole H may be the same for all the resistance adjustment layers, but the size of the pinhole H may be different for each resistance adjustment layer. In other words, among the resistance adjusting layers R, R1, and R2, if the pinhole H is formed relatively large on the upstream side with respect to the flow of electrons, the amount of current can be effectively reduced, and the resistance can be further increased. A simple CPP spin valve element can be formed.

Further, the first embodiment according to the second embodiment of the present invention.
Similarly to the first embodiment, the ferromagnetic layer, the ferromagnetic layer / non-magnetic layer laminated structure, the ferromagnetic layer / ferromagnetic layer, Having a configuration such as a laminated structure of the above.

On the other hand, the non-magnetic intermediate layer S according to the second embodiment of the present invention can also have the same laminated structure as described above with respect to the first embodiment of the present invention.

Also, as for the antiferromagnetic layer A in the second embodiment of the present invention, it is desirable to use a metal antiferromagnetic material having excellent magnetization pinning characteristics, as in the first embodiment.
Specifically, PtMn, NiMn, FeMn, IrMn
And the like can be used. It is desirable that the thickness of these layers be as small as possible in view of electrical characteristics. However, if the thickness is too small, the magnetization pinning characteristics are deteriorated. Therefore, it is necessary to select a film thickness that does not decrease the blocking temperature. Therefore, it is desirable that the film thickness be 5 nm or more.

Further, in addition to the above structure, a so-called synthetic antiferromagnetic layer structure may be employed in one or both of the first magnetic layer P and the second magnetic layer F. Further, in addition to the above configuration, a so-called dual configuration in which the pinned layer P has two layers may be adopted. These points are also as described above with reference to FIG. 16 regarding the first embodiment.

Further, also in the present embodiment, it is desirable to provide a base layer (buffer layer) and a protective layer. This point is as described in detail with reference to FIG. 17 regarding the first embodiment.

Next, embodiments of the present invention will be described in more detail with reference to examples.

(First Embodiment) First, a first embodiment of the present invention will be described.

FIG. 21 is a conceptual diagram showing a sectional configuration of a main part of a magnetoresistive element according to the first embodiment of the present invention.
In forming this magnetoresistive effect element, first, a Cu lower electrode EL1 was laminated to a thickness of 500 nm on a thermally oxidized silicon (Si) substrate (not shown) by a sputtering method, and formed into a 9 μm-wide stripe by photolithography. Thereafter, a 3 μm square CPP-SV film was formed thereon. The film configuration is as shown in the following materials and film thicknesses. Ta 5 nm (buffer layer B) / NiFe 2 nm (buffer layer B) / PtMn 15 nm (antiferromagnetic layer A) / CoFe 1 nm
(Pin layer P1) / AlOx (resistance adjustment R1) / CoFe 5 nm (pin layer P
2) / Cu 3 nm (nonmagnetic intermediate layer S) / CoFe 5 nm (free layer F) / Cu2 nm (nonmagnetic layer NM1) / AlOx (resistance adjusting layer R2) / Cu2nm (nonmagnetic layer NM2) / Ta5 nm (protective layer C) )

Here, AlOx serving as a resistance adjusting layer is made of A
After a film of 1 (aluminum) was formed, the film was exposed to an oxygen atmosphere to form Al by self-oxidation. In this embodiment, AlOx having a pinhole (not shown) was formed by depositing Al to a thickness of 1 nm and exposing it to oxygen by 1 k Langmuir. That is, in the present embodiment, the AlOx layer provided with the pinhole is the resistance adjusting layer R
1, function as R2.

An AlOx film Z for insulation was further formed on the spin valve structure, and a hole of 0.1 μm square was formed.
An upper electrode EL2 was formed by stacking Cu (copper) thereon to a thickness of about 500 nm by a sputtering method. In the present embodiment, the configuration described above makes it possible to measure the CPP-SV characteristic through a 0.1 μ square hole of the insulating AlOx film Z.

As a result of the measurement at room temperature, the element resistance was 7Ω.
And the rate of change in resistance was 10%.
As a result, a resistance change of 0.7Ω was obtained. Further, it was confirmed that the magnetization of the pinned layer P was satisfactorily fixed, and the magnetization of the laminated structure constituting the pinned layer P was moving integrally. In addition, Hc of the free layer F was also small, and it was confirmed that the magnetization moved integrally with the external magnetic field.

(Comparative Example 1) First, thermally oxidized silicon (S
i) A Cu lower electrode of 500 n is formed on the substrate by sputtering.
m, and formed into a stripe having a width of 9 μm by photolithography. After that, a 3 μm square CP
P-SV was deposited. The film configuration is as follows.

Ta5 nm (buffer layer) / NiFe2n
m (buffer layer) / PtMn 15 nm (antiferromagnetic layer) / CoFe 5 nm (pinned layer) / Cu 3 nm (nonmagnetic intermediate layer) / CoFe 5 nm (free layer) / Cu2 nm (nonmagnetic layer) / Ta5 nm (protective layer) Further, an AlOx insulating film similar to that of FIG. 21 was formed, and a 0.1 μm square hole was formed in AlOx. An upper electrode was formed by stacking Cu thereon to a thickness of 500 nm by a sputtering method. As a result of the measurement at room temperature, the element resistance was 3Ω, and the rate of change in resistance was only 3%. That is, in the present comparative example, only the resistance change amount of 0.09Ω was obtained, and the change amount was about ８ of the first embodiment.

(Second Embodiment) As in the first embodiment, first, a Cu lower electrode is laminated to a thickness of 500 nm on a thermally oxidized silicon (Si) substrate by a sputtering method, and formed into a stripe shape having a width of 9 μm by photolithography. did. afterwards,
A 3 μm square CPP-SV was formed thereon. The film configuration is as follows. Ta 5 nm (buffer layer B) / NiFe 2 nm (buffer layer B) / PtMn 15 nm (antiferromagnetic layer A) / CoFe 1 nm
(Ferromagnetic layer FM1) / AlOx (resistance adjusting layer R1) / CoFe1nm (ferromagnetic layer FM2) / Cu1nm (nonmagnetic layer NM1) / CoFe1nm (ferromagnetic layer FM3) / Cu 1nm (nonmagnetic layer NM2) / CoFe1 nm (ferromagnetic layer FM4) / Cu3 nm (nonmagnetic intermediate layer S) / CoFe1 nm (ferromagnetic layer FM5) / Cu1 nm (nonmagnetic layer NM3) / CoFe1 nm (ferromagnetic layer FM6) / Cu1 nm ( Nonmagnetic layer NM4) / CoFe1 nm (ferromagnetic layer FM7) / Cu2 nm (nonmagnetic layer NM5) / AlOx (resistance adjustment layer R2) / Cu2 nm (nonmagnetic layer NM6) / Ta5 nm (protective layer C)

In the above laminated structure, the ferromagnetic material layer FM1
To the ferromagnetic layer FM4 constitute a pinned layer P. Further, a stack of the ferromagnetic layer FM5 to the ferromagnetic layer FM7 or the nonmagnetic layer NM6 constitutes a free layer F.

Further, A constituting the resistance adjusting layers R1 and R2.
IOx was formed as an AlOx layer having a pinhole by the same method as in the first embodiment.

On the spin valve structure, an AlOx film for insulation was formed in the same manner as in FIG. 21, and a hole of 0.1 μm square was formed. An upper electrode EL2 was formed by stacking Cu thereon to a thickness of 500 nm by a sputtering method. In the present embodiment, the above configuration makes it possible to measure the CPP-SV characteristic through a 0.1 μ square hole of the insulating AlOx film.

As a result of the measurement at room temperature, the element resistance was 9Ω.
And a value of 20% was obtained as the resistance change rate. That is, a resistance change of 1.8Ω was obtained. In addition, it was confirmed that the pinned layer P was satisfactorily fixed in magnetization, and the magnetization of the pinned laminated structure was moving integrally. In addition, Hc of the free layer F was small, and it was confirmed that the magnetization moved integrally with the external magnetic field.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 31 is a conceptual diagram of the structure of the magnetoresistive element according to the third embodiment of the present invention as viewed from the cross section of the film. As shown in FIG. 31, the magnetoresistive element of this embodiment has a lower electrode 31, an underlayer 32,
An antiferromagnetic layer 33, a magnetization fixed layer 34, a nonmagnetic intermediate layer 35,
Magnetization free layer 36, nonmagnetic metal layer 37, nonmagnetic compound layer 3
8 and an upper electrode 39 in this order. The antiferromagnetic layer 33, the pinned layer 34, the nonmagnetic intermediate layer 3
5. The magnetization free layer 36 forms a magnetoresistive film.

The nonmagnetic compound layer 38 is made of B, Si, Ge,
Ta, W, Nb, Al, Mo, P, V, As, Sb, Z
r, Ti, Zn, Pb, Th, Be, Cd, Sc, L
a, Y, Pr, Cr, Sn, Ga, Cu, In, Rh,
Pd, Mg, Li, Ba, Ca, Sr, Mn, Fe, C
It is composed of at least one selected from oxides, nitrides, borides, and carbides of o, Ni, and Rb. Further, it is more preferable that the nonmagnetic compound layer 38 is crystalline.
Substances that can easily obtain crystallinity include B, Si, Ge, W,
Nb, Mo, P, V, Sb, Zr, Ti, Zn, Pb,
An oxide containing at least one selected from Cr, Sn, Ga, Fe, and Co can be used. In this specification, the crystalline means that the nonmagnetic compound layer is made of a single crystal or polycrystal. It does not mean a state in which fine crystals are scattered in the amorphous. This is a cross section TEM (Transmission Electron Microscopy)
For example, it can be easily confirmed by observing a lattice image. For example, if an ordered arrangement is observed, it can be said that the substance is crystalline. Alternatively, in the electron beam diffraction image,
When a spot-like pattern is observed, the irradiation range of the electron beam is substantially a single crystal and can be determined to be crystalline. When a ring-shaped pattern is obtained, the irradiation range of the electron beam is in a polycrystalline state and can be determined to be crystalline. The state of epitaxial growth with the lower layer can be confirmed by observing the lattice image.

The non-magnetic compound layer 38 has the effect of increasing the film thickness by the electron reflection effect, and can increase the output. When the non-magnetic compound layer 38 contains a metal phase, a semi-metal phase, a half-metal phase in the layer, or has a film quality in which a pinhole is vacant, the non-magnetic compound layer 38 has an effect of reducing the current and is effectively The effect of increasing the current density occurs. Therefore, the output increases. In order to obtain such an effect, if the ratio of the nonmagnetic compound phase to the metal phase is too large at this time, the resistance will increase too much and the heat generation of the element will increase, deteriorating the characteristics of the element.
Therefore, the metal layer portion is desirably 2% or more.
Also, if the metal phase portion is too large, the effect of increasing the current density is weakened, so it is desirable that the content is at least 30% or less.

The existence of a metal phase or a pinhole in the layer can be confirmed by observing a lattice image of a cross-sectional TEM. That is, when there is a portion in the nonmagnetic compound layer that is epitaxially connected to the upper and lower metal layers, this portion can be said to be a metal phase. Further, by performing composition analysis in the nonmagnetic compound layer, the presence or absence of a metal phase can be confirmed. That is, if the oxygen concentration, the nitrogen concentration, or the fluorine concentration or the boron concentration is less than 20% in composition ratio, it can be said that the material is substantially a metal phase.

The average diameter of the metal phase portion or the pinhole portion is 10% to 1% with respect to the sum of the thicknesses of the magnetization free layer, the nonmagnetic intermediate layer and the magnetization fixed layer.
It is desirably in the range of 00%. If it is 10% or less, the increase in resistance due to narrowing is too large, and is not practical. Conversely, if it is 100% or more, the current spreads too much, and the narrowing effect cannot be obtained. In the case where the magnetization pinned layer is antiferromagnetically coupled via a nonmagnetic metal layer such as Ru (synthetic antiferromagnetic structure), only the ferromagnetic layer closer to the nonmagnetic intermediate layer is considered. , The sum of the film thicknesses must be calculated.

It is desirable that the in-plane spacing of such a metal phase portion or a pinhole portion is in the range of 1 nm to 100 nm. If the thickness is less than 1 nm, the current once narrowed will overlap near the non-magnetic compound layer, and the effect will be degraded. Also 10
If it is 0 nm or more, the number of existing elements in the actual device is 1
, The characteristics are stochastically dispersed.

When the nonmagnetic compound layer 38 is amorphous, the steepness of the electron potential at the film interface is lost,
Since elastic scattering is suppressed, a very large electron reflection effect cannot be obtained, and an increase in output cannot be expected. In the case of amorphous, the structure is unstable and the heat resistance is deteriorated, which causes output deterioration. In order to obtain a crystalline nonmagnetic compound layer, for example, B, Si, Ge, W, Nb, M
o, P, V, Sb, Zr, Ti, Zn, Pb, Cr, S
A compound selected from oxides of rare earth metals such as n, Ga, Fe, and Co is desirable for obtaining crystallinity.

The nonmagnetic compound layer 38 has a thickness of 0.2 nm.
Below, the thickness must be 0.2 nm or more in order to easily change its form by thermal diffusion. Also,
On the other hand, when the thickness is 10 nm or more, the resistance of the element increases, causing excessive heat generation when a sense current is applied, which causes output deterioration. More preferably 0.5
It is desirable to be in the range of 5 nm to 5 nm. However, when the nonmagnetic compound layer 38 is formed of a semi-metal, a half-metal,
And this is not the case when the compound is a metal.

The non-magnetic metal layer 37 comprises a non-magnetic compound layer 38
In order to stabilize the compound, it is desirable to use an element having low reactivity. For example, Cu, Au, Ag, Ru, I
A metal layer containing at least one selected from r, Re, Rh, Pt, Pd, and Os is also effective from this viewpoint. Al can also be used for the nonmagnetic metal layer 37, but at this time, the nonmagnetic compound layer 38 is preferably made of a material that is more easily oxidized than Al. When comparing the nonmagnetic metal layer 37 with the nonmagnetic compound layer 38, the nonmagnetic compound layer 38 is preferably a compound of an element mainly containing an element different from the element of the nonmagnetic metal layer 37. This is because, when the binding energies of oxygen, nitrogen, carbon, and boron are the same, oxygen is easily diffused, and it is difficult to maintain the thermal stability of the nonmagnetic compound layer 38. However, compounds that are very resistant to diffusion can be made depending on the method of making the compound. For example, the ions of the elements that combine
Compounds formed by generating plasma and radicals and irradiating the metal layer are very stable, and do not show very remarkable diffusion between the compound phase of the same kind of metal element and the metal phase.
Furthermore, the compound layer and the above-mentioned Cu, Au, Ag, Ru, Ir, Re, Rh,
A combination with a nonmagnetic metal layer containing at least one selected from Pt, Pd, Al, and Os has very good thermal stability.

The non-magnetic compound layer 38 does not necessarily have to be in the form of a layer as shown in FIG. 32, and may be formed in the form of an island inside the non-magnetic metal layer 37. Also in this case, the materials required for the non-magnetic metal layer 37 and the non-magnetic compound layer 38 are the same as those in FIG. It is desirable that the in-plane spacing of such an island compound is in the range of 1 nm to 100 nm. If the thickness is less than 1 nm, the current once narrowed will overlap near the non-magnetic compound layer, and the effect will be degraded. Also 100n
If it is not less than m, the actual number of elements present in the device will be on the order of one to three, and the variation in characteristics will increase stochastically. Further, it is desirable that the in-plane area ratio of the island portion and the metal portion therebetween is in the range of 2% to 30%.

In order to form a metal phase portion or a structure in which a pinhole is formed in the nonmagnetic compound layer described above, it is preferable to combine substances having different oxidation energies. In particular, the substances forming the metal phase portion include the above-mentioned Cu, Au, Ag, Ru, Ir, Re, Rh, P
It is desirable that a metal containing at least one selected from t, Pd, Al, and Os be a main component. At this time, when the atoms forming the nonmagnetic compound layer diffuse into the metal phase portion, the resistance of the metal phase portion increases, which may cause a practical problem. Therefore, the atoms forming the metal phase,
It is desirable that the atoms forming the compound phase be substantially insoluble.

For example, when the main component of the metal phase portion is Cu, the main components forming the nonmagnetic compound layer are B, Fe, M
It is preferable that at least one selected from the group consisting of o, Pb, Ta, Cr, V, Si, Sb, and Ge is the main component. More preferably, B, Fe, M which tends to be crystalline
It is preferable that at least one selected from the group consisting of o, Pb, Cr, V, Si, Sb, and Ge is the main component.

For example, when the main component of the metal phase portion is Au, the main components forming the nonmagnetic compound layer are B, Fe, G
It is preferable that at least one selected from e, Mo, P, Rh, Si, W, and Cr is a main component. More preferably, B, Fe, Mo, P, Si, W,
It is desirable that at least one selected from Cr is a main component.

For example, when the main component of the metal phase portion is Ag, the main components forming the nonmagnetic compound layer are B, Be, C
o, Cr, Fe, Mo, Pb, Si, Ta, V, W, Ge, Sn,
It is desirable that at least one selected from Al and Rh is a main component. More preferably, B, Be, Co, Cr, Fe, Mo, Pb, Si, V,
At least one selected from W, Ge, Sn, Al, Rh
It is desirable that one is the main component.

For example, when the main component of the metal phase portion is Pt, it is preferable that the main component forming the non-magnetic compound layer is W as the main component.

For example, when the main component of the metal phase portion is Pd, it is preferable that the main component forming the nonmagnetic compound layer be W and Cr.

As a means for forming the above-mentioned combination of the metal phase and the non-magnetic compound phase, a non-magnetic compound may be formed in the layer of the substance forming the metal phase or at the interface. As a method for forming the non-magnetic compound, the non-magnetic compound may be formed by irradiating a reactive gas after film formation, or the non-magnetic compound may be directly laminated by sputtering or the like.

As another means for forming the above-mentioned combination of the metal phase and the non-magnetic compound phase, a method of forming an alloy layer of a material forming the metal phase and a material forming the non-magnetic compound layer, It can also be formed by irradiating a gas. Such an alloy layer can be formed, for example, by stacking alloy targets by sputtering or the like. The alloy target is preferably made of a combination of the above-mentioned insoluble materials. These are non-solid solutions, but a target can be created by sintering, or a mosaic of two substances may be used.

The lower electrode 31 is made of Cu, Au, Ag, R
u, Ir, Re, Rh, Pt, Pd, Al, Os, Ni
A metal containing a substance selected from the above is used. The underlayer 32 includes NiFeCr, Ta / NiFeCr, Ta /
Ru, Ta / NiFe, Ta / Cu, Ta / Au and the like are used. The laminated structure of Ta and fcc or a metal layer of HCP is important for obtaining good film growth. In particular, in order to obtain good soft magnetism of the magnetization free layer, the fcc structure
It is important to obtain the (111) orientation, and the structure of the underlayer 32 is required.

This embodiment also has an appropriate resistance value, a large MR change amount, and a C value which is magnetically highly sensitive.
A PP type magnetoresistive element can be obtained.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 33 is a conceptual diagram of the structure of the magnetoresistive element according to the third embodiment of the present invention as viewed from the cross section of the film. The magnetoresistive element according to this embodiment includes a lower electrode 31, an underlayer 32, an antiferromagnetic layer 33, a pinned layer 34, a nonmagnetic intermediate layer 35, a magnetization free layer 36, a nonmagnetic metal layer 37, and a nonmagnetic compound layer. 38 and an upper electrode 39 in this order. The antiferromagnetic layer 33,
The magnetization fixed layer 34, the nonmagnetic intermediate layer 35, and the magnetization free layer 36 form a magnetoresistive film.

The non-magnetic intermediate layer 35 has a non-magnetic compound layer 38.
And mixed state. At this time, as shown in FIG. 34, the nonmagnetic compound 38 may be precipitated in the nonmagnetic intermediate layer 35 or may be granular. The nonmagnetic compound 38 may penetrate the nonmagnetic intermediate layer 35 in a direction perpendicular to the plane (see FIG. 35). Further, it is not always necessary to be in the film of the nonmagnetic intermediate layer 35, and it may be formed at the interface (see FIG. 36). By forming such a structure, there is an effect that the element size is effectively reduced and the current density is increased, and the output can be increased. As described in the third embodiment, such a current narrowing effect is also effective when formed on the side opposite to the nonmagnetic intermediate layer 35 when viewed from the magnetization free layer 36, but in the present embodiment. The narrowing effect is stronger when it is formed almost at the center of the portion directly related to the magnetoresistance effect as shown in FIG. If the nonmagnetic compound layer 38 is amorphous, thermal diffusion may occur, which may adversely affect the mean free path in the nonmagnetic intermediate layer 35. For this reason, crystalline is preferred. At this time, the nonmagnetic compound layer 3
If the ratio of 8 is too large, the resistance will increase too much and the heat generation of the element will increase, thus deteriorating the characteristics of the element. Therefore, the metal layer portion is desirably 2% or more. Also, if the metal phase portion is too large, the effect of increasing the current density is weakened, so it is desirable that the content is at least 30% or less.

The existence of a metal phase or a pinhole in the layer can be confirmed by observing a lattice image of a cross-sectional TEM. That is, when there is a portion in the nonmagnetic compound layer that is epitaxially connected to the upper and lower metal layers, this portion can be said to be a metal phase. Further, by performing composition analysis in the nonmagnetic compound layer, the presence or absence of a metal phase can be confirmed. That is, if the oxygen concentration, the nitrogen concentration, or the fluorine concentration or the boron concentration is less than 20% in composition ratio, it can be said that the material is substantially a metal phase.

However, in order to obtain a good magnetoresistance effect, it is important that electrons pass through the non-magnetic intermediate layer without being scattered. Therefore, the oxygen concentration, or nitrogen concentration, or the fluorine concentration or boron concentration,
Desirably, the composition ratio is less than 15%.

The average diameter of the metal phase portion or the pinhole portion is 10% to 1% with respect to the sum of the thicknesses of the magnetization free layer, the nonmagnetic intermediate layer and the magnetization fixed layer.
It is desirably in the range of 00%. If it is 10% or less, the increase in resistance due to narrowing is too large, and is not practical. Conversely, if it is 100% or more, the current spreads too much, and the narrowing effect cannot be obtained. In the case where the magnetization pinned layer is antiferromagnetically coupled via a nonmagnetic metal layer such as Ru (synthetic antiferromagnetic structure), only the ferromagnetic layer closer to the nonmagnetic intermediate layer is considered. , The sum of the film thicknesses must be calculated.

It is desirable that the in-plane spacing of such a metal phase portion or a pinhole portion is in the range of 1 nm to 100 nm. If the thickness is less than 1 nm, the current once narrowed will overlap near the non-magnetic compound layer, and the effect will be degraded. More preferably, the thickness is 10 nm or more. If the thickness is 100 nm or more, the actual number of elements present in the device becomes about 1 to 3 levels, and the variation in characteristics increases stochastically.

In order to form a metal phase portion in the non-magnetic compound layer or to form a structure in which a pinhole is formed as described above, it is preferable to combine substances having different oxidation energies. In particular, as the substance forming the metal phase portion in the non-magnetic intermediate layer, the above-mentioned Cu, Au, Ag, Ru, Ir,
It is desirable that a metal containing at least one selected from Re, Rh, Pt, Pd, Al, and Os be a main component.
At this time, when the atoms forming the nonmagnetic compound layer diffuse into the metal phase portion, the resistance of the metal phase portion increases, which may cause a practical problem. Therefore, it is desirable that the atoms forming the metal phase and the atoms forming the compound phase are substantially insoluble.

For example, when the main component of the metal phase portion is Cu, the main components forming the nonmagnetic compound layer are B, Fe, M
It is preferable that at least one selected from o, Pb, Ta, Cr, V, Si, Sb, and Ge is a main component.
More preferably, B, Fe, Mo, P
It is preferable that at least one selected from b, Cr, V, Si, Sb, and Ge is a main component.

For example, when the main component of the metal phase portion is Au, the main components forming the nonmagnetic compound layer are B, Fe, G
It is preferable that at least one selected from e, Mo, P, Rh, Si, W, and Cr is a main component. More preferably, B, Fe, Mo, P, Si, W,
It is desirable that at least one selected from Cr is a main component.

For example, when the main component of the metal phase portion is Ag, the main components forming the nonmagnetic compound layer are B, Be, C
o, Cr, Fe, Mo, Pb, Si, Ta, V, W, Ge, Sn,
It is desirable that at least one selected from Al and Rh is a main component. More preferably, B, Be, Co, Cr, Fe, Mo, Pb, Si, V,
At least one selected from W, Ge, Sn, Al, Rh
It is desirable that one is the main component.

For example, when the main component of the metal phase portion is Pt, it is desirable that the main component forming the non-magnetic compound layer be W as the main component.

For example, when the main component of the metal phase portion is Pd, it is preferable that the main component forming the non-magnetic compound layer be W and Cr.

As a means for forming the above-mentioned combination of the metal phase and the non-magnetic compound phase, a non-magnetic compound may be formed in the layer of the substance forming the metal phase or at the interface. As a method for forming the non-magnetic compound, the non-magnetic compound may be formed by irradiating a reactive gas after film formation, or the non-magnetic compound may be directly laminated by sputtering or the like.

As another means for forming the above-mentioned combination of the metal phase and the non-magnetic compound phase, a method of forming an alloy layer of a substance forming the metal phase and a non-magnetic compound layer and then forming It can also be formed by irradiating a gas. Such an alloy layer can be formed, for example, by laminating an alloy target by sputtering or the like. The alloy target is preferably made of a combination of the above-mentioned insoluble materials. These are non-solid solutions, but a target can be created by sintering, or a mosaic of two substances may be used.

This embodiment also has an appropriate resistance value, a large MR change amount, and a C value which is magnetically highly sensitive.
A PP type magnetoresistive element can be obtained.

(Fifth Embodiment) Next, as a fifth embodiment of the present invention, a magnetic head using the magnetoresistance effect element of the present invention will be described.

FIG. 22 is a conceptual perspective view showing a main configuration of a magnetic head using the magnetoresistive element of the present invention. That is, the magnetic head of the present invention has a pair of magnetic yokes 102, 102 arranged facing the recording medium 200. On the magnetic yokes 102, 102, a magnetoresistive element 104 magnetically coupled thereto is provided. The magneto-resistance effect element 104 is a CP of the present invention as described above with reference to FIGS. 1 to 21 and 31 to 34.
It is a P-type element. Also, a pair of magnetic yokes 10
A pair of bias layers 106 and 106 are formed at both ends so as to straddle 2 and 102. Bias layer 10
Numeral 6 is made of an antiferromagnetic material or a ferromagnetic material, and acts so as to direct the magnetization of the magnetic yoke 102 and the free layer of the magnetoresistive element 104 in a direction perpendicular to the recording magnetic field, that is, in the y direction in FIG.

The recording medium 200 includes a recording track 200
T is formed, and the recording bits 200B are arranged. Signal magnetization as illustrated by the arrows is formed in each recording bit 200B, and a signal magnetic flux from these recording bits is given to a magnetic circuit connecting the magnetic yoke 102 and the magnetoresistive element 104. Magnetoresistive element 10
When the magnetic field of the recording bit 200B is applied to 4, the magnetization of the free layer rotates in the plane from the y direction by the bias layer 106. Then, the change in the magnetization direction is detected as a change in the magnetic resistance.

In order to match the magnetic detection area of the magnetoresistive element 104 with the size of the recording bit 200B, the contact of the electrode of the magnetoresistive element 104 is limited to an area corresponding to the width W of the recording track shown in FIG. It is formed.

According to the present invention, the magnetoresistance effect element 104
By using the CPP type element of the present invention as described above with reference to FIGS. 1 to 21 and FIGS. 31 to 34, it is possible to achieve both an appropriate element resistance and a large change in magnetoresistance. That is, it is possible to realize a magnetic head having much higher sensitivity and more stable reliability than the conventional one.

In the present embodiment, the magnetic head adapted to the magnetic recording medium of the longitudinal (in-plane) recording method has been described as an example, but the present invention is not limited to this.
The same effect can be obtained by applying the magnetoresistive element of the present invention similarly to a magnetic head adapted to a perpendicular recording medium.

(Sixth Embodiment) Next, as a sixth embodiment of the present invention, a magnetic recording / reproducing apparatus using the magnetoresistive element of the present invention will be described. 1 to 21 and 3
The magnetoresistance effect element of the present invention as described above with reference to FIGS. 1 to 34 is mounted on a magnetic head as exemplified in FIG. 22, and is incorporated in, for example, a magnetic recording / reproducing integrated magnetic head assembly to form a magnetic recording / reproducing apparatus. Can be applied.

FIG. 23 is a perspective view of an essential part illustrating a schematic configuration of such a magnetic recording / reproducing apparatus. That is, the magnetic recording / reproducing device 150 of the present invention is a device using a rotary actuator. In the figure, a longitudinal recording or perpendicular recording magnetic disk 200 is mounted on a spindle 152 and is rotated in the direction of arrow A by a motor (not shown) responding to a control signal from a drive controller (not shown). A head slider 153 for recording and reproducing information stored in the magnetic disk 200 is attached to a tip of a thin-film suspension 154. here,
The head slider 153 has, for example, a magnetic head on which the magnetoresistive element of the present invention described above in the first and second embodiments is mounted, near the tip thereof.

When the magnetic disk 200 rotates, the medium facing surface (ABS) of the head slider 153 is held at a predetermined flying height from the surface of the magnetic disk 200.

The suspension 154 is connected to one end of an actuator arm 155 having a bobbin for holding a drive coil (not shown). The other end of the actuator arm 155 is provided with a voice coil motor 156, which is a type of linear motor. The voice coil motor 156 includes a drive coil (not shown) wound around a bobbin portion of the actuator arm 155, and a magnetic circuit including a permanent magnet and an opposing yoke which are arranged opposite to sandwich the coil.

[0211] The actuator arm 155 is
It is held by ball bearings (not shown) provided at two positions above and below 57, and can be freely rotated and slid by a voice coil motor 156.

FIG. 24 is an enlarged perspective view of the magnetic head assembly ahead of the actuator arm 155 as viewed from the disk side. That is, the magnetic head assembly 1
Numeral 60 has an actuator arm 151 having a bobbin for holding a drive coil, for example. A suspension 154 is connected to one end of the actuator arm 155.

At the tip of the suspension 154, a head slider 153 having a reproducing magnetic head using the magnetoresistive element of the present invention is attached. A recording head may be combined. The suspension 154 has lead wires 164 for writing and reading signals, and the lead wires 164 are electrically connected to the respective electrodes of the magnetic head incorporated in the head slider 153. In the figure, reference numeral 165 denotes an electrode pad of the magnetic head assembly 160.

Here, between the medium facing surface (ABS) of the head slider 153 and the surface of the magnetic disk 200,
A predetermined flying height is set.

Slider 153 on which magnetic head 10 is mounted
Operate in a state of flying above the surface of the magnetic disk 200 by a predetermined distance. According to the present invention, even in such a “floating traveling type” magnetic recording / reproducing apparatus, it is possible to perform reproduction with higher resolution and lower noise than before.

On the other hand, the magnetic head 10 and the magnetic disk 20
"Contact traveling type" that positively contacts 0 and travels
It is needless to say that the magnetic recording / reproducing apparatus can reproduce with higher resolution and lower noise than before.

The embodiments of the present invention have been described with reference to the examples. However, the present invention is not limited to these specific examples.

For example, as for the structure as a spin valve element and the material of each layer, the same effect can be obtained by applying the present invention to all ranges that can be selected by those skilled in the art. For example, the present invention can be similarly applied to a structure such as “dual type”.

Further, the structure of the magnetic head, the material and the shape of each component constituting the magnetic head, etc. are not limited to those described above as specific examples, and all the ranges that can be selected by those skilled in the art are similarly used. It can be effective.

Further, the magnetic recording / reproducing apparatus may be one that performs only reproduction or one that performs recording / reproduction, and the medium is not limited to a hard disk. Any magnetic recording medium such as a magnetic card can be used.
Further, the apparatus may be a so-called "removable" type apparatus in which the magnetic recording medium is removable from the apparatus.

Further, the magnetoresistance effect element according to the present invention can constitute a "magnetic memory cell" for storing magnetic information in combination with a transistor / diode or the like, or alone. That is, the present invention is also applicable to a “magnetic memory device (MRAM)” in which magnetic memory cells are integrated.

[0222]

As described in detail above, according to the present invention,
It is possible to provide a CPP type magnetoresistive element having an appropriate resistance value, a large MR change amount, and high magnetic sensitivity.

As a result, it is possible to reliably read magnetic information from smaller recording bits than in the past, and it is possible to greatly improve the recording density of a recording medium. At the same time, since it is thermally stable, the reliability of the magnetic recording / reproducing system is improved, the range of use is expanded, and industrial advantages are great.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating a cross-sectional structure of a magnetoresistive element according to a first embodiment of the present invention.

2 (a) shows the case where the magnetization of the pinned layer P and the free layer F are parallel, and FIG. 2 (b) shows the case where the potential felt by the electrons is up-spin and down-spin when anti-parallel. It is an illustrated graph.

3A illustrates the case where the magnetization of the pinned layer and the free layer are parallel, and FIG. 3B illustrates the case where the potential felt by electrons is up spin and down spin when antiparallel. It is a graph.

FIG. 4 is a conceptual diagram illustrating a cross-sectional configuration of a specific example of the magnetoresistive element of the present invention.

5A is a configuration in which the position of a pinhole H is the same between upper and lower electron reflection layers R1 and R2, and FIG.
This shows a configuration in which the position of the pinhole H is shifted between the upper and lower electron reflection layers R1 and R2.

FIG. 6 is a conceptual diagram illustrating a configuration including two or more resistance adjustment layers R1A and R1B or R2A and R2B.

FIG. 7 is a conceptual diagram illustrating a configuration in which a resistance adjusting layer R2 is not inserted into a ferromagnetic layer FM but is sandwiched and arranged between nonmagnetic layers NM1 and NM2.

FIG. 8 is a conceptual diagram illustrating a configuration employing a stacked structure of a ferromagnetic layer FM and a non-magnetic layer NM.

FIG. 9 is a conceptual diagram showing a configuration employing a laminated film of two or more ferromagnetic materials.

FIG. 10 is a conceptual diagram illustrating a case where a ferromagnetic layer sandwiching a resistance adjustment layer is formed of two or more types of ferromagnetic layers.

FIG. 11 shows a ferromagnetic layer FM (fcc) having an fcc structure and b
It is a conceptual diagram showing the structure combined with the ferromagnetic material layer FM (bcc) of a cc structure.

FIG. 12 is a conceptual diagram illustrating a configuration in which a nonmagnetic layer NM has a stacked structure of a first nonmagnetic layer NM1 and a second nonmagnetic layer NM2.

FIG. 13 is a conceptual diagram illustrating a configuration employing a stacked structure of a ferromagnetic material layer FM1 / ferromagnetic material layer FM2.

FIG. 14 is a conceptual diagram illustrating another specific example when a plurality of ferromagnetic layers are provided.

FIG. 15 is a conceptual diagram illustrating another specific example when a plurality of ferromagnetic layers are provided.

FIG. 16 is a conceptual diagram showing a configuration employing a so-called synthetic antiferromagnetic structure.

FIG. 17 is a conceptual diagram showing a configuration employing a base layer (buffer layer) B and a protective layer C.

FIG. 18 is a conceptual diagram illustrating a cross-sectional structure of a magneto-resistance effect element according to a second embodiment of the present invention.

FIG. 19 is a conceptual diagram illustrating a configuration in which pinholes are located at the same location between the respective resistance adjustment layers.

FIG. 20 is a conceptual diagram illustrating a configuration in which the positions of pinholes H are shifted between the respective resistance adjustment layers.

FIG. 21 is a conceptual diagram illustrating a cross-sectional configuration of a main part of the magnetoresistance effect element according to the first example of the present invention.

FIG. 22 is a conceptual perspective view illustrating a main part configuration of a magnetic head using the magnetoresistive element of the present invention.

FIG. 23 is a perspective view of an essential part illustrating a schematic configuration of a magnetic recording / reproducing apparatus.

FIG. 24 is an enlarged perspective view of the magnetic head assembly ahead of the actuator arm 155 as viewed from the disk side.

FIG. 25 is a conceptual diagram illustrating a schematic cross-sectional structure of a spin valve film.

FIG. 26 is a conceptual diagram showing a generally used current supply method.

FIG. 27 is a conceptual diagram illustrating a cross-sectional configuration of a spin valve film.

FIG. 28 is a conceptual diagram illustrating a cross-sectional structure of a CPP-artificial lattice element.

FIG. 29 is a conceptual diagram illustrating a cross-sectional configuration of a CPP-SV element.

FIG. 30 is a diagram illustrating the configuration and operation of a specific example of a resistance adjustment layer.

FIG. 31 is a sectional view showing the configuration of a magnetoresistive element according to a third embodiment;

FIG. 32 is a sectional view showing the configuration of a modification of the third embodiment.

FIG. 33 is a sectional view showing the configuration of the magnetoresistive element according to the fourth embodiment;

FIG. 34 is a sectional view showing a configuration of a modification of the fourth embodiment.

FIG. 35 is a sectional view showing a configuration of a modification of the fourth embodiment.

FIG. 36 is a sectional view showing a configuration of a modification of the fourth embodiment.

[Explanation of symbols]

 A antiferromagnetic layer P magnetization pinned layer (pin layer) R, R1, R2 resistance adjustment layer FM ferromagnetic layer NM nonmagnetic layer S nonmagnetic intermediate layer F magnetization free layer (free layer) EL electrode I sense current B Buffer layer C protective layer 31 lower electrode 32 underlayer 33 antiferromagnetic layer 34 magnetization pinned layer 35 nonmagnetic intermediate layer 36 magnetization free layer 37 nonmagnetic metal layer 38 nonmagnetic crystal layer 39 upper electrode 150 magnetic recording device 151 magnetic disk 153 Head slider 154 Suspension 155 Actuator arm 156 Voice coil motor 157 Fixed axis

Continuation of the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (Reference) H01F 10/32 G01R 33/06 R (72) Inventor Tomohiko Nagata 1-1-1, Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture. Inside the Toshiba Research and Development Center Co., Ltd. (72) Inventor Hiroaki Yoda No. 1, Komukai Toshiba-cho, Yuki-ku, Kawasaki City, Kanagawa Prefecture Inside the Toshiba Research and Development Center Co., Ltd. (72) Inventor Katsuhiko Kounoi Kawasaki, Kanagawa Prefecture No. 1, Komukai Toshiba-cho, Sachi-ku, Toshiba R & D Center, Inc. Hitoshi Iwasaki 1 Toshiba, Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba R & D Center (72) Inventor Masaji Sabashi 1-Toshiba-cho, Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Inside the Development Center (72) Inventor Masayuki Takagishi 1st plant, Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Company Toshiba Research and Development Center in the F-term (reference) 2G017 AA10 AD55 5D034 BA03 5E049 AA01 AA04 AA09 AC00 AC05 BA12 CB02 DB12

Claims (20)

[Claims] A magnetization fixed layer having a ferromagnetic film having a magnetization direction substantially fixed to one side; a magnetization free layer having a ferromagnetic film having a magnetization direction that changes in accordance with an external magnetic field; A magnetoresistive film having a non-magnetic intermediate layer provided between the free layer and the magnetization fixed layer; and the magnetoresistive film for applying a current in a direction perpendicular to the film surface of the magnetoresistive film. A magnetoresistive effect comprising: a pair of electrodes electrically connected to each other; and a resistance adjustment layer containing oxide, nitride, fluoride, carbide, or boride as a main component. element. 2. A magnetization fixed layer having a ferromagnetic film whose magnetization direction is substantially fixed to one side, a magnetization free layer having a ferromagnetic film whose magnetization direction changes according to an external magnetic field, A magneto-resistance effect film having a non-magnetic intermediate layer provided between the free layer and the magnetization fixed layer; and the magneto-resistance effect film for applying a current in a direction perpendicular to a film surface of the magneto-resistance effect film. A magnetoresistive element, comprising: a pair of electrodes electrically connected to each other; and a resistance adjusting layer that restricts an amount of sense current passing through the magnetoresistive film. 3. The resistance adjustment layer according to claim 1, wherein the resistance adjustment layer has a pinhole with an aperture ratio of 50% or less.
The magnetoresistive element according to any one of the preceding claims. 4. The magnetoresistive element according to claim 1, wherein said resistance adjusting layer is composed of two or more metal elements. 5. The method according to claim 1, wherein the resistance adjusting layer is formed inside the magnetization free layer or on a side of the magnetization free layer opposite to a side on which the nonmagnetic intermediate layer is formed. The magnetoresistance effect element according to claim 1. 6. The magnetoresistive element according to claim 1, wherein said resistance adjusting layer is formed in a film of said nonmagnetic intermediate layer or at an interface. 7. The resistance adjusting layer is formed in a film of the magnetization fixed layer or on a side of the fixed layer opposite to a side on which the nonmagnetic intermediate layer is formed. The magnetoresistance effect element according to claim 1. 8. The resistance adjusting layer is made of B, Si, Ge, T
a, W, Nb, Al, Mo, P, V, As, Sb, Z
r, Ti, Zn, Pb, Th, Be, Cd, Sc, L
a, Y, Pr, Cr, Sn, Ga, Cu, In, Rh,
Pd, Mg, Li, Ba, Ca, Sr, Mn, Fe, C
7. The magnetoresistive element according to claim 6, wherein the main component is at least one oxide, nitride, fluoride, carbide, or boride selected from o, Ni, and Rb. 9. The resistance adjusting layer is formed on the side of the magnetization free layer opposite to the side on which the non-magnetic intermediate layer is provided, in the layer of the non-magnetic intermediate layer, or at the interface. ,
2. The magnetoresistive element according to claim 1, comprising at least one metal of Ru, Ir, Re, Rh, Pt, Pd, Al and Os. 10. The resistance adjusting layer is formed on the side of the magnetization free layer opposite to the side on which the nonmagnetic intermediate layer is provided, in the layer of the nonmagnetic intermediate layer, or at the interface, and contains Cu as a main component. A first region, B, Fe, Mo, Pb, Ta, Cr, V,
A second region mainly containing an oxide, nitride, fluoride, carbide, or boride containing at least one selected from Si, Sb, and Ge. 1 mounted magnetoresistance effect element. 11. The resistance adjusting layer is formed on a side of the magnetization free layer opposite to a side on which the nonmagnetic intermediate layer is provided, in a layer of the nonmagnetic intermediate layer, or at an interface, and contains Au as a main component. B, Fe, Ge, Mo, P, R
an oxide containing at least one selected from the group consisting of h, Si, W, and Cr, or a nitride, or a fluoride, or a carbide, or a second region mainly containing boride. The magnetoresistance effect element according to claim 6. 12. The resistance adjusting layer is formed on a side of the magnetization free layer opposite to the side on which the nonmagnetic intermediate layer is provided, in a layer of the nonmagnetic intermediate layer or at an interface, and contains Ag as a main component. And the first region, Be, Co, Cr, Fe, Mo, P
b, Si, Ta, V, W, Ge, Sn, Al, Rh, or a second region mainly containing an oxide, a nitride, a fluoride, a carbide, or a boride. 2. The magnetoresistive element according to claim 1, further comprising: 13. A magnetization fixed layer having a ferromagnetic film whose magnetization direction is substantially fixed to one side, a magnetization free layer having a ferromagnetic film whose magnetization direction changes in accordance with an external magnetic field, A magneto-resistance effect film having a non-magnetic intermediate layer provided between the free layer and the magnetization fixed layer; and the magneto-resistance effect film for applying a current in a direction perpendicular to a film surface of the magneto-resistance effect film. A pair of electrodes electrically connected to, on the surface of the magnetization free layer opposite to the side on which the nonmagnetic intermediate layer is provided, or formed in the film or interface of the nonmagnetic intermediate layer, B, Si, Ge, W, Nb, Mo,
P, V, Sb, Zr, Ti, Zn, Pb, Cr, Sn,
And a region containing at least one selected from Ga, Fe, and Co and containing a crystalline oxide as a main component. 14. The resistance adjusting layer has a thickness of 0.5 to 5n.
2. The magnetoresistance effect element according to claim 1, wherein m is equal to or less than m. 15. The magnetoresistive element according to claim 1, wherein said resistance adjusting layer contains 2% to 30% of metal phase holes. 16. The average diameter of the holes in the metal phase is 5% to 100% of the sum of the thicknesses of the magnetization free layer, the nonmagnetic intermediate layer, and the magnetization pinned layer. The magnetoresistance effect element according to claim 15, wherein: 17. The method according to claim 17, wherein the distance between the holes of the metal phase is 10 to 1.
The magnetoresistance effect element according to claim 15, wherein the thickness is 00 nm. 18. The magnetoresistive element according to claim 15, wherein an average interval between holes of said metal phase is 10 to 100 nm. 19. A magnetic head comprising the magnetoresistive element according to claim 1. Description: 20. A magnetic reproducing apparatus comprising the magnetic head according to claim 19, wherein said magnetic head is capable of reading magnetic information stored in a magnetic recording medium.