JP5424178B2 - Spin injection device and magnetic apparatus using the same - Google Patents

Description

  The present invention is applied to a functional device that controls the spin of electrons, particularly a super gigabit large capacity, high speed, nonvolatile magnetic memory, and a spin injection device for enabling spin injection magnetization reversal at a smaller current density. The present invention relates to a spin injection magnetic device and a spin injection magnetic memory device.

In recent years, giant magnetoresistive (GMR) effect elements composed of ferromagnetic layers / nonmagnetic metal layers / ferromagnetic layers and ferromagnetic spin tunnel junction (MTJ) elements composed of ferromagnetic layers / insulator layers / ferromagnetic layers have been developed. Applications to new magnetic field sensors and magnetic memories (MRAM) are expected.
GMR achieves a giant magnetoresistance effect by controlling the magnetizations of two ferromagnetic layers in parallel or antiparallel to each other by an external magnetic field, resulting in different resistances due to spin-dependent scattering at the interface. . On the other hand, the MTJ has a so-called tunnel magnetoresistance (TMR) effect in which the magnitudes of tunnel currents in the direction perpendicular to the film surface are different from each other by controlling the magnetizations of two ferromagnetic layers in parallel or antiparallel to each other by an external magnetic field. Obtained (for example, see Non-Patent Document 1).

The tunnel magnetoresistance TMR depends on the spin polarizability P _{1 at} the interface between the ferromagnet and the insulator to be used. If the spin polarizabilities of the two ferromagnets are P ₁ and P ₂ , respectively, the following equation ( It is known to be given in 1).

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

Currently, the maximum tunneling magnetoresistance TMR obtained at room temperature is about 50 percent when using a CoFe alloy of P-0.5.
GMR elements have already been put to practical use in hard disk magnetic heads. The MTJ element is currently expected to be applied to a hard disk magnetic head and a non-volatile magnetic memory (MRAM).
In the MRAM, MTJ elements are arranged in a matrix, and a magnetic field is applied by passing a current through a separately provided wiring, thereby controlling the two magnetic layers constituting each MTJ element in parallel and antiparallel to each other. 1 ”and“ 0 ”are recorded. Reading is performed using the TMR effect.
However, MRAM has a problem to be solved that if the element size is reduced to increase the capacity, the current required for magnetization reversal increases due to an increase in the demagnetizing field and the power consumption increases.

  As a method for solving such a problem, a three-layer structure in which two magnetic layers are coupled in antiparallel via a nonmagnetic metal layer (artificial antiferromagnetic film, hereinafter referred to as “SyAF”). Have been proposed (see, for example, Patent Document 1).

When such a SyAF structure is used, the demagnetizing field is reduced, so that the magnetic field required for magnetization reversal is reduced even if the element size is reduced.
On the other hand, recently, a new spin inversion method that does not use a current magnetic field has been theoretically proposed (for example, see Non-Patent Document 2) and has been experimentally realized (for example, see Non-Patent Document 3).

  As shown in FIG. 15, the spin inversion method uses a second ferromagnetic layer in a three-layer structure including a first ferromagnetic layer 61 / nonmagnetic metal layer 63 / second ferromagnetic layer 65. When a current is passed from 63 to the first ferromagnetic layer 61, spin-polarized electrons are injected from the first ferromagnetic layer 61 into the second ferromagnetic layer 65 through the nonmagnetic metal layer 63, The spin of the ferromagnetic layer 65 is reversed, which is called magnetization reversal by spin injection.

  If the spin of the first ferromagnetic layer 61 is fixed in the three-layer structure in this spin injection magnetization reversal, when the spin injection from the first ferromagnetic layer 61 through the nonmagnetic metal layer 63 is performed, the injected upward direction The spin (major spin) gives a torque to the spin of the second ferromagnetic layer 65 and aligns the spin in the same direction. Therefore, the spins of the first ferromagnetic layer 61 and the second ferromagnetic layer 65 are parallel.

On the other hand, when the direction of the current is reversed and spin injection is performed from the second ferromagnetic layer 65 to the first ferromagnetic layer 61, a downward spin at the interface between the first ferromagnetic layer 61 and the nonmagnetic metal layer 63 ( The minority spins) are reflected, and the reflected spins apply torque to the spins of the second ferromagnetic layer 65 and attempt to align the spins in the same direction, that is, downward. As a result, the spins of the first ferromagnetic layer 61 and the second ferromagnetic layer 65 are antiparallel.
Therefore, in the spin injection magnetization reversal of this three-layer structure, the spins of the first ferromagnetic layer and the second ferromagnetic layer can be made parallel or antiparallel by changing the direction of the current.

Japanese Patent Laid-Open No. 9-251621 (front page, FIG. 1)

T. Miyazaki and N. Tezuka, “Spin polarized tunneling in ferromagnet / insulator / ferromagnet junctions”, (1995), J. Magn. Magn. Mater., L39, p.1231 J. C. Slonczewski, “Current-driven exitation of magnetic multilayer”, (1996), J. Magn. Magn. Mater., 15, L1-L7 JA Katine, FJ Albert, RA Ruhman, EB Myers and DC Ralph, “Current-Driven Magnetization Reversal and Spin-wave Exitation in Co / Cu / Co Pillars”, (2000), Phy. Rev. Lett., 84, pp. 3149-3152

However, although such a spin injection method is promising as a spin reversal method for a future nanostructured magnetic material, the current density required for magnetization reversal by spin injection is as large as 10 ⁷ A / cm ² or more, which is practical. It was a problem to be solved above.

However, the inventors of the present invention have a three-layer structure in which two ferromagnetic layers are coupled antiparallel to each other via a nonmagnetic metal layer, and a ferromagnetic layer via a separately provided nonmagnetic metal layer or insulating layer. It was found that the magnetization reversal caused by spin injection can be caused at a smaller current density when the current is supplied from.
Further, in place of the three-layer structure, a two-layer structure composed of a ferromagnetic free layer and a non-magnetic layer and a three-layer structure composed of a ferromagnetic free layer, a non-magnetic layer, and a ferromagnetic layer can be used. It was found that an effect can be obtained.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a spin injection device, a magnetic device using the spin injection device, and a magnetic memory device that can reverse the spin injection magnetization with a smaller current density.

In order to achieve the above object, among the spin injection devices of the present invention, the invention according to claim 1 is a spin polarization portion formed of a single ferromagnetic pinned layer and a first formed on the spin polarization portion. A spin injection part having an injection junction made of a nonmagnetic layer, a ferromagnetic free layer provided in contact with the spin injection part, and a second nonmagnetic layer formed on the surface of the ferromagnetic free layer The first nonmagnetic layer is made of an insulator or a conductor, the second nonmagnetic layer is made of any one of Ru, Ir, and Rh, and the first nonmagnetic layer is a conductor. In this case, the first nonmagnetic layer is made of a metal different from that of the second nonmagnetic layer, does not apply an external magnetic field, and is perpendicular to the film plane between the spin polarization portion and the second nonmagnetic layer. The current is passed to reverse the magnetization of the ferromagnetic free layer.
The invention described in claim 2 is characterized in that the first nonmagnetic layer is made of Cu.
According to a third aspect of the present invention, the spin of the second nonmagnetic layer is such that the majority spin is reflected and the minority spin is transmitted at the interface between the second nonmagnetic layer and the ferromagnetic free layer. It is characterized by being within the diffusion length.
The invention according to claim 4 is characterized in that the ferromagnetic free layer is Co or a Co alloy, the second nonmagnetic layer is a Ru layer, and the film thickness thereof is 0.1 to 20 nm.
According to a fifth aspect of the present invention, the ferromagnetic pinned layer and / or the ferromagnetic free layer is made of Co ₂ Fe _x Cr _1-x Al (0 ≦ x ≦ 1) having a crystal structure of B2 or A2. It is characterized by that.
Also, of the spin injection device of the present invention, the invention of claim 5 6, wherein the first non-formed on the spin-polarized portion and the spin polarization unit consisting of a first ferromagnetic pinned layer of a single layer A spin injection part having an injection junction made of a magnetic layer; a ferromagnetic free layer provided in contact with the spin injection part; a second nonmagnetic layer formed on the surface of the ferromagnetic free layer; And a second ferromagnetic pinned layer formed on the second nonmagnetic layer and having the same magnetization direction as the first ferromagnetic pinned layer, wherein the first nonmagnetic layer is an insulator or a conductive material. And the second nonmagnetic layer is made of any one of Ru, Ir, and Rh, and the first nonmagnetic layer is a conductor, the first nonmagnetic layer is the second nonmagnetic layer. The layer is made of a different metal, does not apply an external magnetic field, and is perpendicular to the film plane between the spin polarization portion and the second ferromagnetic pinned layer. It is characterized by passing a current and reversing the magnetization of the ferromagnetic free layer.
The invention described in claim 7 is characterized in that the first nonmagnetic layer is made of Cu.
The invention according to claim 8, the thickness of the second magnetic layer, at the interface between the second non-magnetic layer and the second ferromagnetic pinned layer, so as to transmit a small number spin reflects many spins The ferromagnetic free layer has a thickness that preserves spin conduction.
The invention according to claim 9 is characterized in that the ferromagnetic free layer and the ferromagnetic layer are Co or a Co alloy, and the second nonmagnetic layer is a Ru layer and has a thickness of 2 to 20 nm.
In the invention described in claim 10, any one or two or more of the first ferromagnetic pinned layer, the second ferromagnetic pinned layer, and the ferromagnetic free layer have a B2 or A2 crystal structure. It is characterized by comprising Co ₂ Fe _x Cr _1-x Al (0 ≦ x ≦ 1).

  In the spin injection device having this configuration, when the spin injection is performed from the spin polarized portion through the injection junction, the magnetization of the ferromagnetic free layer is reversed. Therefore, the spin injection device of the present invention can cause magnetization reversal with a smaller current density.

The invention according to claim 11 which is a spin injection magnetic apparatus of the present invention is characterized in that the spin injection device according to any one of claims 1 to 10 is used. In the spin injection magnetic device having this configuration, when the spin injection is performed, the magnetization reversal of the ferromagnetic free layer occurs and becomes parallel or antiparallel to the magnetization of the ferromagnetic fixed layer, thereby causing a giant magnetoresistance effect or a tunnel magnetoresistance effect. . Therefore, the spin injection magnetic device of the present invention can cause magnetization reversal of the ferromagnetic free layer by spin injection with a smaller current density.

The invention of claim 12 wherein the spin injection magnetic memory device of the present invention is characterized by using a spin injection device according to any of claims 1-10. In the spin-injection magnetic memory device having this configuration, when the spin-injection is performed, the magnetization reversal of the ferromagnetic free layer occurs and becomes parallel or anti-parallel to the magnetization of the ferromagnetic fixed layer, so that a giant magnetoresistance effect or a tunnel magnetoresistance effect appears. To do. Therefore, the spin injection magnetic memory device of the present invention can provide a memory device by reversing the magnetization of the ferromagnetic free layer by spin injection with a smaller current density.

According to the spin injection device of the present invention, it is possible to cause magnetization reversal with a small current density. The spin injection magnetic device of the present invention can cause magnetization reversal of the free layer of MTJ by spin injection with a smaller current density.
Therefore, the present invention can be used for various magnetic devices and magnetic memory devices including an ultra-gigabit large-capacity, high-speed and nonvolatile MRAM.

1A and 1B are conceptual diagrams of a spin injection device according to a first embodiment of the present invention, in which FIG. 1A is a diagram illustrating a state in which the spin of SyAF is downward, and FIG. It is. It is the schematic of the spin injection device of 1st Embodiment whose injection | pouring junction part is a nonmagnetic insulating layer. It is the schematic which shows 2nd Embodiment of the spin injection device of this invention. It is the schematic which shows 3rd Embodiment of the spin injection device of this invention. It is a schematic diagram explaining the magnetization reversal of the spin injection device of 3rd Embodiment. It is the schematic which shows 4th Embodiment of the spin injection device of this invention. It is a schematic diagram explaining the magnetization reversal of the spin injection device of 4th Embodiment. It is the schematic of the spin injection magnetic apparatus of this invention. It is sectional drawing of the magnetic thin film which can be used for this invention. It is sectional drawing of the modification of the magnetic thin film which can be used for this invention. Used in the magnetic thin film _{Co 2 Fe x Cr 1-x} Al ( wherein, 0 ≦ x ≦ 1) is a diagram illustrating the structure of a schematically. It is a figure which shows the spin injection magnetization reversal of the spin injection device of Example 1 in room temperature. It is a figure which shows the spin transfer magnetization reversal of the spin injection device of Example 2 at room temperature. It is a figure which shows (a) magnetoresistance curve of the comparative example in room temperature, and (b) spin injection magnetization reversal. It is the schematic which shows the principle of the conventional spin magnetization reversal.

Hereinafter, the present invention will be described in detail based on the embodiments shown in the drawings. In each figure, the same or corresponding members are denoted by the same reference numerals.
FIG. 1 is a conceptual diagram of a spin injection device according to the present invention. FIG. 1A is a conceptual diagram illustrating a state in which the spin of SyAF is downward, and FIG. 1B is a conceptual diagram illustrating a state in which the spin of SyAF is upward due to spin injection.

As shown in FIG. 1, the spin injection device 10 of the present invention includes a spin injection unit 1 having a spin polarization unit 9 and an injection junction 7 and a nonmagnetic layer 2 that is antiferromagnetically coupled. The magnetic layer 4 and the second magnetic layer 6 include a SyAF 3 that forms a three-layer structure, and these form a stacked structure.
First, SyAF3 according to the present invention will be described.
The magnetic field Hsw necessary for the magnetization reversal of the single layer film of the ferromagnet is generally given by the following equation (2) using the uniaxial magnetic anisotropy Ku, the saturation magnetization Ms, the film thickness t, and the width w.

Hsw = 2Ku / Ms + C (k) tMs / w (2)
Here, the first term is a term due to magnetic anisotropy, and the second term is a term due to a demagnetizing field.

On the other hand, when similarly adopting a single domain structure, the magnetization reversal field of SyAF having the film thicknesses t ₁ and t ₂ and the saturation magnetizations M ₁ and M ₂ of the two ferromagnetic layers is given by the following equation (3).

Hsw = 2Ku / ΔM + C (k) (t ₁ + t ₂ ) ΔM / w (3)
Here, ΔM = (t ₁ + t ₂ ) / (M ₁ t ₁ −M ₂ t ₂ ), w is the width of SyAF.

In the above formulas (2) and (3), C (k) is a demagnetizing factor coefficient that depends on the aspect ratio k, and decreases as k approaches 1, and when k = 1, C (k) = 0. . Here, the aspect ratio k is t / w. Therefore, in the case of the first magnetic layer 4, it is t ₁ / w, and in the case of the second magnetic layer 6, it is t ₂ / w (see FIG. 1A).
In the case of a small element, generally, the second term exceeds the first term in both formulas (2) and (3), and since ΔM <Ms, SyAF has a magnetization reversal field when w is the same. Get smaller.
On the other hand, since C (k) becomes zero when k = 1, the magnetization reversal field is determined by the first term of the equations (2) and (3), that is, the magnetic anisotropy, and does not depend on the element size. .
However, in the case of a single layer film, when k is at least 2 or less, a multi-domain structure is formed. Therefore, the magnetization reversal field is not given by Equation (2), and its value becomes larger and depends on the element size. Therefore, in the case of a single layer film, an element with k ≦ 2 is not realistic.

  However, the present inventors have found that in the case of SyAF according to the present invention, a single magnetic domain structure is obtained even when k ≦ 2, particularly k = 1. As a result, the SyAF according to the present invention can obtain a smaller magnetization reversal magnetic field. In particular, in the element with k = 1, the magnetization reversal magnetic field does not depend on the element size. The present invention is based on this discovery, and magnetization reversal can be realized with a smaller current density by injecting spin-polarized electrons into SyAF. In particular, when k = 1, C (k) becomes zero, and the magnetization reversal magnetic field becomes extremely small.

  Such a SyAF 3 according to the present invention has two magnetic layers of a first magnetic layer 4 and a second magnetic layer 6 through a nonmagnetic layer 2 with reference to FIGS. 1 (a) and 1 (b). Are magnetically coupled antiparallel to each other, and each film thickness is formed in a nanometer size. Magnetization reversal of SyAF 3 is realized by spin-injecting into SyAF 3 from spin-polarized portion 9 of the ferromagnetic layer through injection junction 7 of the nonmagnetic metal layer of spin injection portion 1.

  The nonmagnetic layer 2 is a substance that antiferromagnetically couples the magnetizations of both magnetic layers through the nonmagnetic layer 2, and ruthenium (Ru), iridium (Ir), and rhodium (Rh) can be used as the antiferromagnetic nonmagnetic layer. is there. In FIG. 1A, reference numerals 5 and 8 denote terminals for flowing current. Since the ferromagnetic layer and the magnetic layer are conductors, they can also be used as electrodes. However, a current may be supplied by separately providing electrodes.

As shown in FIG. 1B, in the SyAF 3 according to the present invention, the spin of the first magnetic layer 4 and the spin of the second magnetic layer 6 are magnetically coupled while maintaining an antiparallel state. Yes. That is, the magnetization of the first magnetic layer 4 and the magnetization of the second magnetic layer 6 have antiparallel magnetizations with different magnitudes, that is, antiparallel spins with different magnitudes.
When the thickness of the first magnetic layer 4 is t ₁ , the magnetization is M ₁ , the thickness of the second magnetic layer 6 is t ₂ , and the magnetization is M ₂ , the direction of the larger magnetization (t ₁ M ₁ −t ₂ M ₂ ) can be the SyAF spin direction ↑ or ↓ with respect to the arrow indicating the spin of the ferromagnetic layer 9 in FIG. In order to provide a difference in the magnitude of the antiparallel magnetization of the magnetic layer 4 and the magnetic layer 6 of SyAF3, t ₁ M ₁ and t ₂ M ₂ may be made different from each other.

The spin injection part 1 has a structure in which a spin polarization part 9 made of a ferromagnetic layer and an injection junction part 7 made of a nonmagnetic conductive layer are laminated, and the injection junction part 7 of the nonmagnetic conductive layer has a nanometer size. Here, the nanometer size means a size that allows electrons to conduct while preserving their momentum and spin. That is, the injection junction 7 has a size capable of spin conservation conduction.
In the case of a metal, the mean free path of electrons is 1 μm or less, and in an element having a size of 1 μm or less, injected spin can flow into the other without relaxation.
The injection junction 7 of the spin injection part 1 may be a nonmagnetic insulating layer 12 as shown in FIG. This nonmagnetic insulating layer 12 has a nanometer size of a size capable of tunnel junction through which a tunnel current flows, and is several nm.

  The spin-polarized portion 9 made of a ferromagnetic layer is a ferromagnet, but the number of up-spin electrons and down-spin electrons on the Fermi surface responsible for conduction is different. Spin-polarized electrons flow into the injection junction 7 of the nonmagnetic metal layer.

  In such a spin injection device according to the present invention, a very small current of 1 milliampere (mA) or less is passed, and the spin-polarized portion 9 of the ferromagnetic layer is perpendicular to the non-magnetic metal layer (or non-magnetic layer). When spin injection is performed through the injection junction 7 of the magnetic insulating layer 12), the spin of the magnetic layer 4 of the SyAF 3 and the spin of the magnetic layer 6 are reversed in magnetization while maintaining an antiparallel state. Therefore, in the spin injection device of the present invention, magnetization can be reversed by spin injection with a smaller current density. As a result, spin injection magnetization can be reversed only by passing a minute current without passing a current and applying a magnetic field, so that a spin injection device having logic, memory, and storage can be realized.

  Next, a second embodiment will be described. FIG. 3 is a schematic view showing a second embodiment of the spin injection device of the present invention. Referring to FIG. 3, in this embodiment, the spin polarization part 9 has a structure having an antiferromagnetic layer 21 and a ferromagnetic layer 23, and the antiferromagnetic layer 21 is brought close to the ferromagnetic layer 23. Thus, the spin of the ferromagnetic layer 23 is fixed. The injection junction is a nonmagnetic metal layer 25 capable of spin conservation conduction, and an insulating layer capable of tunnel junction may be used instead. In such a configuration, the spin in the spin polarization portion is fixed and spin injection is performed, and the magnetization reversal of SyAF can be performed.

Next, a third embodiment will be described. FIG. 4 is a schematic view showing the spin injection device of the third embodiment. Referring to FIG. 4, the spin injection device 14 includes a spin polarization portion 9 including an antiferromagnetic layer 21 and a ferromagnetic pinned layer 26, and a nonmagnetic member serving as an injection junction provided in contact with the ferromagnetic pinned layer. The layer 7 and the nonmagnetic layer 7 are provided with a two-layer structure including a ferromagnetic free layer 27 and a nonmagnetic layer 28.
The spin injection part 1 is composed of a spin polarization part 9 and an injection junction part 7. In the spin polarization part 9, the antiferromagnetic layer 21 is brought close to the ferromagnetic fixed layer 26 so that the ferromagnetic fixed layer 26. The spin is fixed.
The injection junction 7 is a non-magnetic metal layer 25 such as Cu capable of conducting spin conservation, and an insulating layer 12 capable of tunnel junction may be used instead.

The spin injection device 14 of the third embodiment is different from the spin injection device shown in FIG. 3 in that a ferromagnetic free layer 27 and a nonmagnetic layer 28 are provided instead of SyAF3. The nonmagnetic layer 28 is provided to reflect a majority (majority) spin and transmit a minority (minority) spin at the interface with the ferromagnetic free layer 27. Therefore, the film thickness of the nonmagnetic layer 28 may be set within the distance that the minority spin can move while preserving the spin, that is, within the spin diffusion length.
Here, as the ferromagnetic free layer 27, Co or Co alloy can be used. As the nonmagnetic layer 28, Ru, Ir, and Rh can be used, and it is particularly preferable to use Ru. Further, it is known that the spin diffusion length of Ru is 14 nm, and the film thickness of Ru may be 0.1 nm to 20 nm. In the following description, it is assumed that Co or a Co alloy is used for the ferromagnetic free layer 27 and Ru is used for the nonmagnetic layer 28.

FIG. 5 is a schematic diagram for explaining the magnetization reversal of the spin injection device 14 of the third embodiment. In FIG. 5, when electrons are injected from the ferromagnetic pinned layer 26 to the ferromagnetic free layer 27, the torque 18 is applied so that the majority spin electrons 17 align the magnetization of the ferromagnetic free layer 27 with the magnetization of the ferromagnetic pinned layer 26. give. At this time, it is known that, at the interface between Co or Co alloy 27 and Ru 28, the majority spin electrons are strongly scattered (reflected) and the minority spin electrons are not much scattered (transmitted).
Therefore, as shown in FIG. 5, the majority spin electrons 19 reflected at the interface between Co or Co alloy 27 and Ru 28 can be obtained as long as the film thickness of Co or Co alloy 27 is thin enough to preserve spin conduction. The reflected majority spin electrons 19 give the same torque 18 ′ to the ferromagnetic free layer 27. As a result, the torque of the ferromagnetic free layer 27 is substantially increased and becomes the same direction as the magnetization of the ferromagnetic pinned layer 26.

On the other hand, when the direction of current is reversed and electrons are injected from the Ru layer 28 to the Co or Co alloy 27 side, the majority spin electrons are reflected at the interface between the Co or Co alloy 27 and Ru 28, and only the minority spin electrons are Co or The minority spin electrons are injected into the ferromagnetic free layer 27 made of a Co alloy, and torque is applied to the spins of the ferromagnetic free layer 27 to try to align the spins in the same direction, that is, downward. As a result, the torque due to the minority spin electrons of the ferromagnetic free layer 27 increases, and the spin of the ferromagnetic free layer 27 becomes antiparallel to the magnetization of the ferromagnetic pinned layer 26.
Thus, according to the spin injection device 14 of the present invention, by inserting the nonmagnetic layer 28, the spin of the spin polarization portion 9 is fixed and spin injection is performed, and the magnetization reversal of the ferromagnetic free layer 27 is performed by conventional spin injection. It can be performed at a lower current density than the magnetization reversal.

Furthermore, a spin injection device according to a fourth embodiment will be described with reference to FIG. The spin injection device 16 of this embodiment is different from the spin injection device 14 shown in FIG. 4 in that a ferromagnetic pinned layer 29 is further provided on the nonmagnetic layer 28. The other configuration is the same as that of the spin injection device 14 shown in FIG.
Here, in the ferromagnetic free layer 27 and the ferromagnetic pinned layer 29, the film thickness of the nonmagnetic layer 28 can be determined so that their magnetizations do not become antiparallel like SyAF3 and spin conservation conduction occurs. That's fine. Therefore, when Co or Co alloy is used as the ferromagnetic free layer 27 and the ferromagnetic pinned layer 29 and Ru is used as the nonmagnetic layer 28, the thickness of Ru is about 2 to 20 nm so as not to be SyAF3. do it.

Next, the operation of the spin injection device 16 of the fourth embodiment will be described.
In FIG. 6, when electrons are injected from the ferromagnetic pinned layer 26 to the ferromagnetic free layer 27, the ferromagnetic free layer 27 made of Co or Co alloy is formed as in the spin injection device 14 of the third embodiment. The magnetization is in the same direction as the magnetization of the ferromagnetic pinned layer 26.

On the other hand, the case where the direction of current is given in reverse will be described with reference to FIG.
FIG. 7 is a schematic diagram for explaining the magnetization reversal of the spin injection device 16 of the fourth embodiment. In FIG. 7, when electrons are injected from the ferromagnetic pinned layer 29 to the ferromagnetic free layer 27, the majority spin electrons 37 are strongly reflected at the interface between the ferromagnetic pinned layer 29 and the Ru layer 28, and to the ferromagnetic free layer 27. Will not reach. At this time, if the film thickness of the Co or Co alloy 27 is thin enough to preserve the spin conduction, the minority spin electrons 39 are not scattered and reach the ferromagnetic free layer 27, and the spin of the ferromagnetic free layer 27. Torque 38 is applied so that Therefore, the magnetization of the ferromagnetic free layer 27 is antiparallel to the ferromagnetic fixed layer 26. Thereby, the majority spin electrons 37 do not reach the ferromagnetic free layer 27 and the magnetization can be reversed with a smaller current density than in the case without the Ru layer 28.
As described above, according to the spin injection device 16 of the present embodiment, the spin of the spin polarization unit 9 is fixed and spin injection is performed, and the ferromagnetic free layer 27, the nonmagnetic layer 28, and the ferromagnetic fixed used instead of SyAF3. In the layer 29, the magnetization reversal of the ferromagnetic free layer 27 can be performed at a low current density.

In the above spin injection device, when the magnetization reversal of the ferromagnetic free layer 27 occurs, it becomes parallel or antiparallel to the magnetization of the ferromagnetic pinned layer 26, so that the antiferromagnetic layer 21, the ferromagnetic pinned layer 26, Cu, etc. The layer structure including the injection junction 7 made of the nonmagnetic metal layer 25 and the ferromagnetic free layer 27 produces a giant magnetoresistive effect as in the case of the CPP giant magnetoresistive element.
In addition, when the magnetization reversal of the ferromagnetic free layer 27 occurs when the nonmagnetic layer 7 is the insulating layer 12 capable of tunnel junction, the insulating layer 12 capable of tunnel junction with the antiferromagnetic layer 21 and the ferromagnetic pinned layer 26 The layer structure including the ferromagnetic free layer 27 produces a tunnel magnetoresistive effect as in the case of the CPP type tunnel magnetoresistive element.

  Next, the spin injection magnetic device of the present invention will be described. FIG. 8 is a schematic view of the spin injection magnetic apparatus of the present invention. The spin injection magnetic device 30 is a ferromagnetic spin tunnel junction (MTJ) element 36 in which a free layer SyAF 3 and a fixed layer 31 composed of a ferromagnetic layer 32 and an antiferromagnetic layer 34 are tunnel-joined by an insulating layer 33. The MTJ element 36 is provided with a spin injection part 1 for reversing the magnetization of a free layer that is a ferromagnetic layer. The spin injection part 1 is an insulating layer 12 in which the injection junction part can be tunneled.

  In such a spin injection magnetic device, when the spin injection is performed from the ferromagnetic layer 23 to the SyAF 3 through the insulating layer 12, the magnetization of the SyAF 3 is reversed. The magnetization of the free layer of SyAF3 is reversed to ↑ or ↓ and becomes parallel or antiparallel to the magnetization of the fixed layer 31, so that a tunnel magnetoresistance (TMR) effect appears. Therefore, the spin injection magnetic device 30 can cause magnetization reversal of the free layer by spin injection with a smaller current density.

In the above spin injection magnetic apparatus, SyAF3 is replaced with a two-layer structure comprising the ferromagnetic free layer 27 and the nonmagnetic layer 28 provided on the ferromagnetic free layer of the spin injection device 14 of the third embodiment shown in FIG. It is good also as a structure.
In the spin injection magnetic device, the SyAF 3 includes the ferromagnetic free layer 27, the nonmagnetic layer 28, and the ferromagnetic layer 29 provided on the nonmagnetic layer of the spin injection device 16 of the fourth embodiment shown in FIG. It is good also as a structure replaced with a three-layer structure.

  Thus, the spin injection magnetic device of the present invention can be used for a super gigabit large capacity, high speed, non-volatile memory.

In such a spin injection magnetic device, SyAF of the free layer is sandwiched or covered by an insulating film capable of tunnel junction, and is finely processed by being coupled as a word line at the spin injection part corresponding to this SyAF, The basic structure of the MRAM or spin-injection magnetic memory device can be obtained by connecting a bit line to the ferromagnetic layer and performing microfabrication.
Here, in addition to SyAF, the free layer is a two-layer structure comprising a ferromagnetic free layer 27 and a nonmagnetic layer 28, or a ferromagnetic free layer 27, a nonmagnetic layer 28, and a ferromagnetic layer 29 provided on the nonmagnetic layer. A three-layer structure can be used.

Next, a magnetic thin film that can be used in the spin injection device and the spin injection magnetic apparatus of the present invention will be described.
FIG. 9 is a cross-sectional view of a magnetic thin film that can be used in the present invention. As shown in FIG. 9, in the magnetic thin film 41, a Co ₂ Fe _x Cr _1-x Al thin film 43 is disposed on a substrate 42 at room temperature. Here, 0 ≦ x ≦ 1.
_{Co 2 Fe x Cr 1-x} Al thin film 43 is a ferromagnetic at room temperature, the electrical resistivity is about 190μΩ · cm, and any one of L2 _1, B2, A2 structure without heating the substrate Has one structure.
Further, by heating the substrate which is disposed the _{Co 2 Fe x Cr 1-x} Al thin film 43, _{Co 2 Fe x Cr 1-x} Al thin film 43 of large L2 ₁ structure of the spin polarization ratio can be easily obtained. The thickness of the _{Co 2 Fe x Cr 1-x} Al thin film 43 on the substrate 42, may be at 1nm or 1μm or less.

FIG. 10 is a cross-sectional view of a modification of the magnetic thin film that can be used in the present invention. The magnetic thin film 45 used in the present invention has a buffer layer between the substrate 42 and the Co ₂ Fe _x Cr _1-x Al (where 0 ≦ x ≦ 1) thin film 43 in the structure of the magnetic thin film 41 of FIG. 44 is inserted. By inserting the buffer layer _{44, Co 2 Fe x Cr 1} -x Al on the substrate 41 (here, 0 ≦ x ≦ 1) can be better the crystallinity of the thin film 43.

The substrate 42 used for the magnetic thin films 41 and 45 may be a polycrystalline such as thermally oxidized Si or glass, or a single crystal such as MgO, Al ₂ O ₃ or GaAs. As the buffer layer 44, Al, Cu, Cr, Fe, Nb, Ni, Ta, NiFe, or the like can be used.
(Where, 0 ≦ x ≦ 1) the _{Co 2 Fe x Cr 1-x} Al film thickness of the thin film 43 may be any 1μm or less 1nm or more. If this film thickness is less than 1 nm, it becomes difficult to obtain substantially any one of the L2 ₁ , B2 and A2 structures described later, and if this film thickness exceeds 1 μm, it can be applied as a spin injection device. It becomes difficult and not preferable.

Next, the operation of the magnetic thin film having the above configuration will be described.
FIG. 11 is a diagram schematically illustrating the structure of Co ₂ Fe _x Cr _1-x Al (where 0 ≦ x ≦ 1) used for the magnetic thin film. The structure shown in the figure shows a structure that is 8 times (2 times the lattice constant) of a conventional unit cell of bcc (body-centered cubic lattice).
Co in the L2 ₁ structure _{2 Fe x Cr 1-x Al} , ( where, 0 ≦ x ≦ 1) Fe x Cr 1-x As Fe and Cr composition ratio in the position of I in FIG. 9 so that the Al is arranged at the position of II, and Co is arranged at the positions of III and IV.
Further, in the B2 structure of Co ₂ Fe _x Cr _1-x Al, Fe, Cr, and Al are irregularly arranged at positions I and II in FIG. At this time, the composition ratio of Fe and Cr is arranged so as to _satisfy FexCr1 _-x (where 0 ≦ x ≦ 1).
Furthermore, in the A2 structure of Co ₂ Fe _x Cr _1-x Al, Co, Fe, Cr, and Al are irregularly substituted. At this time, the composition ratio of Fe and Cr is arranged so as to _satisfy FexCr1 _-x (where 0 ≦ x ≦ 1).

Next, the magnetic properties of the magnetic thin films 41 and 45 having the above configuration will be described.
(Where, 0 ≦ x ≦ 1) above configuration of _{Co 2 Fe x Cr 1-x} Al thin film 43 is a ferromagnetic at room temperature, and any L2 _1, B2, A2 structure without heating the substrate A Co ₂ Fe _x Cr _1-x Al thin film having one structure can be obtained.
Furthermore, (where, 0 ≦ x ≦ 1) above configuration of _{Co 2 Fe x Cr 1-x} Al thin film 43 either be L2 _1, B2, A2 structure in a very thin film of about several nm film thickness One structure is obtained.
Here, the B2 structure of the Co ₂ Fe _x Cr _1-x Al (where 0 ≦ x ≦ 1) thin film is a unique substance that has not been obtained conventionally. The B2 structure is similar to the L2 ₁ structure, but the difference is that in the L2 ₁ structure, Cr (Fe) and Al atoms are regularly arranged, whereas the B2 structure is irregularly arranged. It is that. The A2 structure is a structure in which Co, Fe, Cr and Al are irregularly substituted. These differences can be measured by X-ray diffraction.
In composition x of the _{Co 2 Fe x Cr 1-x} Al thin film 43, 0 Within ≦ x ≦ 0.8, in particular, L2 _1, to obtain any one of the structures of B2 without heating the substrate Can do. Further, when 0.8 ≦ x ≦ 1.0, the A2 structure is obtained.
Further, in the composition x, within the range of 0 ≦ x ≦ 1, it is possible to form a Co ₂ Fe _x Cr _1-x Al thin film on a heated substrate, or heat treatment after the film is formed without heating. , L2 ₁ or B2 structure is obtained.

Although it is difficult to experimentally clarify that the magnetic thin films 41 and 45 having the above structure are half-metals, a tunnel magnetoresistive element having a tunnel junction is qualitatively produced so that it exceeds 100%. When a very large TMR is shown, it can be considered as a half metal.
A Co ₂ Fe _x Cr _1-x Al (0 ≦ x ≦ 1) thin film 43 is used as a ferromagnetic layer on one side of the insulating film, and a CoFe alloy having a spin polarizability of 0.5 is formed on the other ferromagnetic layer of the insulating film. As a result of producing a tunnel magnetoresistive effect element, a large TMR exceeding 100% was obtained.

This indicates that the Co ₂ Fe _x Cr _1-x Al (0 ≦ x ≦ 1) thin film 43 has a spin polarizability of P = 0.7 or more in view of the equation (1). Was able to obtain such large TMR, in addition to the _{Co 2 Fe x Cr 1-x} Al (0 ≦ x ≦ 1) thin film 3 has a high spin polarizability, L2 at room temperature Based on the discovery that one of the ₁ , B2, and A2 structures can be obtained.
Thereby, according to the magnetic thin films 41 and 45, it is not necessary to heat the substrate, and the Co ₂ Fe _x Cr _1-x Al (0 ≦ x ≦ 1) thin film 43 has a ferromagnetic property with a thickness of 1 nm or more. Can do. This is because the surface of the tunnel junction can be made clean and sharp without oxidizing the surface or increasing the surface roughness. It is assumed that a large TMR can be obtained.

  The magnetic thin films 41 and 45 can be used for the first and second magnetic layers of SyAF3 used in the spin injection device of the present invention, the ferromagnetic layer 9 of the spin injection part, or the like. The magnetic thin films 41 and 45 are composed of an antiferromagnetic layer 21, a ferromagnetic pinned layer 26, a nonmagnetic metal layer 25 such as Cu, and a ferromagnetic free layer 28 used in the spin injection devices 14 and 16 of the present invention. CPP type giant magnetoresistive effect element structure having a structure, or a tunnel magnetoresistive effect element having a layer structure comprising an antiferromagnetic layer 21, a ferromagnetic pinned layer 26, an insulating layer 12 capable of tunnel junction and a ferromagnetic free layer 28. Can be used for structure. Furthermore, it can be used for the ferromagnetic layer of the MTJ element or tunnel magnetoresistive effect element used in the spin injection magnetic device of the present invention.

Next, Example 1 will be described. Example 1 corresponds to the structure of the spin injection device 14 shown in FIG.
Using a magnetron sputtering method, Ta (2 nm) / Cu (20 nm) / IrMn (10 nm) / Co ₉₀ Fe ₁₀ (5 nm) / Cu (6 nm) / Co ₉₀ Fe ₁₀ (2.5 nm) are formed on a thermally oxidized Si substrate. / Ru (0.45 nm) / Cu (5 nm) / Ta (2 nm) were sequentially sputtered.
Here, the upper layer of Ta and Cu on the thermally oxidized Si substrate is a layer to be an electrode. The IrMn layer and the Co ₉₀ Fe ₁₀ layer are the spin-polarized portions 9 composed of the antiferromagnetic layer 21 and the ferromagnetic fixed layer 26, respectively. Cu is an injection joint 7. Co ₉₀ Fe ₁₀ and Ru of the Co alloy are the ferromagnetic free layer 27 and the nonmagnetic layer 28 disposed on the Cu of the nonmagnetic layer 7.
Next, this film was finely processed using electron beam lithography and Ar ion milling to produce a spin injection device 14 as shown in FIG. The element size is 300 × 100 nm ² .

FIG. 12 is a diagram showing the spin injection magnetization reversal of the spin injection device 14 of Example 1 at room temperature. In the figure, the horizontal axis indicates the spin injection device current (mA) when the current from the ferromagnetic free layer 27 to the ferromagnetic pinned layer 26 is in the positive direction, and the vertical axis indicates the resistance (Ω) at that time. ing. First, an external magnetic field H was applied to the spin injection device 14 to obtain an antiparallel state, that is, a high resistance initial state. The external magnetic field H at this time is 50 Oe (Oersted) (see A in FIG. 12).
As is clear from the figure, it can be seen that when the current is passed from the high resistance state of the minute current shown in A to about 5 mA shown in B in the positive direction, the resistance rapidly decreases and the magnetization is reversed. Furthermore, it can be seen that this low resistance state is maintained even when the current is increased to 20 mA (see B to C in FIG. 12).
Next, when the current is decreased and further applied in the negative direction, the low resistance is maintained up to about −7.5 mA (see C to D in FIG. 12). It can be seen that when a negative current higher than that is applied, the state again becomes a high resistance state and the magnetization is reversed (see E to F in FIG. 12). The current density required for this magnetization reversal was 2.4 × 10 ⁷ A / cm ² , which was about 1/10 of the comparative example described later. The magnetoresistance (MR) was 0.97% as shown in the figure, and the same value as the magnetoresistance in the spin inversion structure of the comparative example described later was obtained.
Thereby, in the spin injection device 14 of the first embodiment, the resistance can be changed by changing the direction of the current flowing therethrough to develop the magnetization reversal of the ferromagnetic free layer 27.

Next, Example 2 will be described. Example 2 corresponds to the structure of the spin injection device 16 shown in FIG.
Using a magnetron sputtering method, Ta (2 nm) / Cu (20 nm) / IrMn (10 nm) / Co ₉₀ Fe ₁₀ (5 nm) / Cu (6 nm) / Co ₉₀ Fe ₁₀ (2.5 nm) are formed on a thermally oxidized Si substrate. / Ru (6 nm) / Co ₉₀ Fe ₁₀ (5 nm) / Cu (5 nm) / Ta (2 nm) were sputtered in this order.
Here, the upper layer of Ta and Cu on the thermally oxidized Si substrate is a layer to be an electrode. The IrMn layer and the Co ₉₀ Fe ₁₀ layer are the spin-polarized portions 9 composed of the antiferromagnetic layer 21 and the ferromagnetic pinned layer 26, respectively. Cu is an injection joint 7. Co ₉₀ Fe ₁₀ , Ru, and Co ₉₀ Fe ₁₀ of the Co alloy are the ferromagnetic free layer 27, the nonmagnetic layer 28, and the ferromagnetic layer 29 disposed on the Cu of the nonmagnetic layer 7, respectively.

The spin injection device 16 of Example 2 is different from the spin injection device 14 of Example 1 in that the thickness of Ru 28 on Co ₉₀ Fe ₁₀ 27 is increased from 0.45 nm to 6 nm, and the ferromagnetic layer 29 is used. This is to provide a Co ₉₀ Fe ₁₀ layer 29 having a thickness of 5 nm.
Next, a spin injection device 16 having an element size of 100 × 100 nm ² was fabricated by the same method as in Example 1.

FIG. 13 is a diagram showing the spin injection magnetization reversal of the spin injection device 16 of Example 2 at room temperature. In the figure, the horizontal axis indicates the spin injection device current (mA) when the current from the ferromagnetic free layer 27 to the ferromagnetic pinned layer 26 is in the positive direction, and the vertical axis indicates the resistance (Ω) at that time. ing. The external magnetic field H applied to obtain a high resistance initial state is 150 Oe.
As can be seen from the figure, the spin injection device 16 of Example 2 changes its resistance at a current of about ± 0.2 mA and exhibits magnetization reversal, similar to the spin injection device 14 of Example 1. The current density required for this magnetization reversal was 1 × 10 ⁶ A / cm ² . This value is about 1/24 of Example 1 and about 1/200 of a comparative example described later. The magnetoresistance was about 1%, and the same value as the magnetoresistance (MR) of a comparative example described later was obtained. Thus, the current density required for the magnetization reversal could be lowered by setting the film thickness of Ru, which is the nonmagnetic layer 28, to 6 nm.

Next, Example 3 will be described. Example 3 is for a structure corresponding to FIG.
First, Cu (100 nm) / NiFe (3 nm) / IrMn (10 nm) / Co ₉₀ Fe ₁₀ (3 nm) was formed on a thermally oxidized Si substrate by using a magnetron sputtering method. Next, SiO ₂ having a thickness of 3 nm is sputtered on this film, and then Co ₉₀ Fe ₁₀ (1 nm) / Ru (0.45 nm) / Co ₉₀ Fe ₁₀ (1.5 nm) / SiO ₂ (3 nm). ) Was sputtered. Next, Co ₉₀ Fe ₁₀ (10 nm) / IrMn (10 nm) / Ta (5 nm) was formed as the upper magnetic layer.

As a result of examining the cross section of this film using a transmission electron microscope, Co ₉₀ Fe ₁₀ (1 nm) / Ru (0.45 nm) / Co ₉₀ Fe ₁₀ (1.5 nm) was dispersed in a single layer in SiO _2. It was found to be a double tunnel structure having an insulating matrix of SiO ₂ . With respect to this structure, a voltage was applied between the upper and lower Cu and Ta films to pass a current, and the resistance at that time was measured at room temperature by changing the current. As a result, a resistance jump was observed at about 0.1 mA. . This is due to the expression of TMR accompanying the magnetization reversal of Co ₉₀ Fe ₁₀ (1 nm) / Ru (0.45 nm) / Co ₉₀ Fe ₁₀ (1.5 nm) SyAF, which means that the magnetization was reversed by spin injection. ing.

(Comparative example)
Next, a comparative example will be described.
In the comparative example, an antiferromagnetic layer is further provided on the first ferromagnetic layer 61 having a three-layer structure used in the conventional spin inversion method shown in FIG. That is, in the spin injection device 14 of Example 1, as a structure without a Ru layer, Ta (2 nm) / Cu (20 nm) / IrMn (10 nm) / Co ₉₀ Fe ₁₀ (5 nm) / Cu (6 nm) is formed on a thermally oxidized Si substrate. ) / Co ₉₀ Fe ₁₀ (2.5 nm) / Cu (5 nm) / Ta (2 nm). Next, the element size was set to 300 × 100 nm ² by the same method as in Example 1.

FIG. 14 is a diagram showing a comparative example (a) magnetoresistance curve and (b) spin injection magnetization reversal at room temperature. In FIG. 14A, the horizontal axis is the applied magnetic field (Oe), and the vertical axis is the resistance (Ω). The device current is 1 mA. The magnetic resistance was measured by sweeping the external magnetic field from 0 (see G in FIG. 14A).
As is apparent from FIG. 14A, it can be seen that the magnetoresistance (MR) of the comparative example is 1.1%, which is the same value as reported conventionally. In FIG. 14B, the horizontal axis indicates the current (mA) when the current flows from the second ferromagnetic layer 63 to the first ferromagnetic layer 61, and the vertical axis indicates the current. Shows the resistance (Ω). As is clear from FIG. 14 (b), by switching the current from positive to negative in the direction of the arrow from almost 0, magnetization reversal occurred as in Example 1 (K to in FIG. 14 (b)). L). The magnetic resistance was 0.98%, and the current density required for magnetization reversal was 2.4 × 10 ⁸ A / cm ² .

Next, the comparison of an Example and a comparative example is demonstrated.
In the example, the current density required for the magnetization reversal was lower than that in the comparative example. In particular, when the film thickness of the Ru layer 28 is in the range of 2 to 20 nm as in Example 2, the current density required for magnetization reversal is 1 × 10 ⁶ A / cm ² , which is 1/10 of the conventional example. It was found that the reduction can be achieved.

The present invention is not limited to these examples, and various modifications are possible within the scope of the invention described in the claims, and it goes without saying that these are also included in the scope of the present invention. .

1: Spin injection part 2: Nonmagnetic layer 3: SyAF
4: First magnetic layer 6: Second magnetic layer 7: Injection junction 9: Spin polarization part 10, 14, 16: Spin injection device 12: Nonmagnetic insulating layer 17, 37: Multiple spin electrons 18, 18 ', 38: Torque 19: Many spin electrons reflected at the interface between Co or Co alloy and Ru 21: Antiferromagnetic layer 23: Ferromagnetic layer 25: Nonmagnetic metal layer 27: Ferromagnetic free layer 28: Ferromagnetic free Nonmagnetic layer 29 provided on the layer: Ferromagnetic layer 30 provided on the nonmagnetic layer: Spin injection magnetic device 31: Fixed layer 32: Ferromagnetic layer 33: Insulating layer 36: MTJ element 39: Minority spin electrons 41, 45: Magnetic thin film 42: Substrate 43: Co ₂ Fe _x Cr _1-x Al thin film 44: Buffer layer

Claims (12)

A spin injection part having a spin polarization part made of a single ferromagnetic pinned layer and an injection junction part made of a first nonmagnetic layer formed on the spin polarization part;
A ferromagnetic free layer provided in contact with the spin injection part;
A second nonmagnetic layer formed on the surface of the ferromagnetic free layer,
The first nonmagnetic layer is made of an insulator or a conductor;
When the second nonmagnetic layer is made of any one of Ru, Ir, and Rh and the first nonmagnetic layer is a conductor, the first nonmagnetic layer is the second nonmagnetic layer. Made of different metals,
A spin characterized by applying an electric current in a direction perpendicular to the film plane between the spin polarization portion and the second nonmagnetic layer without applying an external magnetic field and reversing the magnetization of the ferromagnetic free layer. Injection device.   The spin injection device according to claim 1, wherein the first nonmagnetic layer is made of Cu.   The thickness of the second nonmagnetic layer is set to be within the spin diffusion length so as to reflect majority spins and transmit minority spins at the interface between the second nonmagnetic layer and the ferromagnetic free layer. The spin injection device according to claim 1, wherein: The ferromagnetic free layer is a Co or Co alloy, the second non-magnetic layer is characterized by its film thickness Ru layer is 0.1 to 20, in any one of claims 1 to 3 The spin injection device described. The ferromagnetic pinned layer and / or the ferromagnetic free layer is Co having a crystal structure of B2 or A2. ₂ Fe _x Cr _1-x The spin injection device according to claim 1, wherein the spin injection device is made of Al (0 ≦ x ≦ 1). A spin injection part having a spin polarization part made of a single first ferromagnetic pinned layer and an injection junction part made of the first nonmagnetic layer formed on the spin polarization part;
A ferromagnetic free layer provided in contact with the spin injection part;
A second nonmagnetic layer formed on the surface of the ferromagnetic free layer;
A second ferromagnetic pinned layer formed on the second nonmagnetic layer and having the same magnetization direction as the first ferromagnetic pinned layer,
The first nonmagnetic layer is made of an insulator or a conductor;
When the second nonmagnetic layer is made of any one of Ru, Ir, and Rh and the first nonmagnetic layer is a conductor, the first nonmagnetic layer is the second nonmagnetic layer. Made of different metals,
An external magnetic field is not applied, and a current is passed in the direction perpendicular to the film plane between the spin-polarized portion and the second ferromagnetic pinned layer to reverse the magnetization of the ferromagnetic free layer, Spin injection device. The spin injection device according to claim 6 , wherein the first nonmagnetic layer is made of Cu. The thickness of the second nonmagnetic layer is within the spin diffusion length so as to reflect majority spins and transmit minority spins at the interface between the second nonmagnetic layer and the second ferromagnetic pinned layer. And
The spin injection device of claim 6 , wherein the ferromagnetic free layer has a thickness that preserves spin conduction. The ferromagnetic free layer and the ferromagnetic layer is Co or Co alloy, the second non-magnetic layer is characterized by its film thickness Ru layer is 2 to 20 nm, of claim 6-8 The spin injection device according to any one of the above. Any one or two or more of the first ferromagnetic pinned layer, the second ferromagnetic pinned layer, and the ferromagnetic free layer have a crystal structure of B2 or A2. ₂ Fe _x Cr _1-x The spin injection device according to claim 6, wherein the spin injection device is made of Al (0 ≦ x ≦ 1). A spin injection magnetic apparatus using the spin injection device according to any one of claims 1 to 10 . A spin injection magnetic memory device using the spin injection device according to any one of claims 1 to 10 .

Images