JP2004207707A - Spin injection device and magnetic device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spin injection device, a spin injection magnetic device, and a spin injection magnetic memory device capable of reversing the magnetization of spin injection at a small current density. <P>SOLUTION: This spin injection device 14 includes a spin injection part 1 comprising a spin polarization part 9 containing a ferromagnetic fixed layer 26 and an injection junction part 7 of a non-magnetic layer and a ferromagnetic free layer 27 provided in contact with the spin injection part 1. The non-magnetic layer 7 consists of an insulator 12 or a conductor 25, and the surface of the ferromagnetic free layer 27 is provided with the non-magnetic layer 28. An electric current is passed in the vertical direction of the film surface of the spin injection device 14, so as to reverse the magnetization of the ferromagnetic free layer 27. This device can be utilized for various magnetic devices and magnetic memory devices including a super-gigabit large-capacitance/high-speed/non-volatile MRAM. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  INDUSTRIAL APPLICABILITY The present invention relates to a spin-injection device which is used for a functional device in which electron spin is controlled, in particular, a super-gigabit large-capacity, high-speed, non-volatile magnetic memory and which enables spin-injection magnetization reversal with a smaller current density, and The present invention relates to a spin injection magnetic device and a spin injection magnetic memory device.

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

  The tunnel magnetic resistivity TMR depends on the spin polarizability P at the interface between the ferromagnetic material and the insulator to be used. If the spin polarizabilities of the two ferromagnetic materials are P1 and P2, respectively, the following formula (1) is generally used. Is known to be given by

_{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 magneto-resistivity TMR at room temperature is about 50 percent when using a P-0.5 CoFe alloy.
GMR elements have already been put to practical use in magnetic heads for hard disks. At present, the MTJ element is expected to be applied to a magnetic head for a hard disk and a nonvolatile magnetic memory (MRAM).
In an MRAM, the MTJ elements are arranged in a matrix, and a current is applied to a separately provided wiring to apply a magnetic field, thereby controlling the two magnetic layers constituting each MTJ element to be parallel and antiparallel to each other. 1 ”and“ 0 ”are recorded. Reading is performed using the TMR effect. However, the MRAM has a problem to be solved in that, when the element size is reduced to increase the capacity, the current required for the magnetization reversal increases due to the increase in the demagnetizing field, and the power consumption increases.

  As a method for solving such a problem, a three-layer structure (artificial antiferromagnetic film, hereinafter referred to as “SyAF”) in which two magnetic layers are coupled to each other antiparallel via a nonmagnetic metal layer is described. Has been proposed (for example, see 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 experimentally realized (for example, see Non-Patent Document 3).

  As shown in FIG. 15, the spin inversion method has a three-layer structure including a first ferromagnetic layer 61 / a non-magnetic metal layer 63 / a second ferromagnetic layer 65, and a second ferromagnetic layer When a current flows 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 via the nonmagnetic metal layer 63, This means that the spin of the ferromagnetic layer 65 is reversed, and is called magnetization reversal by spin injection.

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

On the other hand, when the direction of the current is reversed and spin is injected from the second ferromagnetic layer 65 into the first ferromagnetic layer 61, the 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 a torque to the spins of the second ferromagnetic layer 65 so that the spins are aligned in the same direction, that is, downward. As a result, the spins of the first ferromagnetic layer 61 and the second ferromagnetic layer 65 become antiparallel.
Therefore, in the spin injection magnetization reversal of the 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.

JP-A-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, such a spin injection method is promising as a spin inversion method for a nanostructured magnetic material in the future. However, the current density required for magnetization reversal by spin injection is extremely large at 10 ⁷ A / cm ² or more. This was a problem to be solved.

However, the present inventors have developed a three-layer structure in which two ferromagnetic layers are coupled antiparallel to each other via a non-magnetic metal layer, and a ferromagnetic layer via a separately provided non-magnetic metal layer or an insulating layer. It has been found that when a current is supplied from the magnetic field, magnetization reversal by spin injection can be caused at a smaller current density.
Furthermore, the same effect as described above can be obtained by using a two-layer structure composed of a ferromagnetic free layer and a nonmagnetic layer and a three-layer structure composed of a ferromagnetic free layer, a nonmagnetic layer, and a ferromagnetic layer instead of the three-layer structure. It has been found that an effect can be obtained.

  Accordingly, it is an object of the present invention to provide a spin injection device capable of performing spin injection magnetization reversal with a smaller current density, and a magnetic device and a magnetic memory device using the spin injection device.

  In order to achieve the above object, among the spin injection devices of the present invention, the invention according to claim 1 is characterized in that a spin injection portion having a spin polarization portion and an injection junction portion is magnetically connected via a nonmagnetic layer. An anti-parallel coupled SyAF having a first magnetic layer and a second magnetic layer having different magnitudes of magnetization, wherein the SyAF and the injection junction are joined, and spin-polarized electrons are injected from the spin injection part. The injection is performed so that the magnetization of the first magnetic layer and the magnetization of the second magnetic layer are reversed while maintaining the antiparallel state.

According to a second aspect of the present invention, in addition to the above-described configuration, the injection junction of the spin injection part is one of a nonmagnetic conductive layer and a nonmagnetic insulating layer.
The invention according to claim 3 is characterized in that the injection junction of the spin injection part is capable of performing either spin preservation conduction or tunnel junction for spin-polarized electrons.
The invention according to claim 4 is characterized in that the spin polarization part of the spin injection part is a ferromagnetic layer.
The invention according to claim 5 is characterized in that the spin polarization part of the spin injection part is provided in contact with the antiferromagnetic layer for fixing the spin of the ferromagnetic layer.
According to a sixth aspect of the present invention, the aspect ratio of the first magnetic layer and the second magnetic layer of SyAF joined to the injection junction of the spin injection part is 2 or less.

  In the spin injection device having such a configuration, when spin injection is performed from the spin polarization section through the injection junction, the spin of the SyAF is reversed while maintaining the antiparallel state. Therefore, the spin injection device of the present invention can cause the magnetization reversal with a smaller current density.

In the spin injection magnetic device of the present invention, the invention according to claim 7 is characterized in that the first magnetic layer and the second magnetic layer having different magnitudes of magnetization magnetically coupled antiparallel via the nonmagnetic layer are provided. A free layer capable of reversing the magnetization while maintaining the anti-parallel state of the magnetizations of the first magnetic layer and the second magnetic layer, and a ferromagnetic fixed layer tunnel-joined with the free layer and an insulating layer. And a ferromagnetic pinned layer and a free layer having a ferromagnetic spin tunnel junction.
According to an eighth aspect of the present invention, in addition to the above configuration, a spin injection unit having an injection junction and a spin polarization unit joined to the free layer is provided.

According to a ninth aspect of the present invention, the injection junction of the spin injection part is one of a non-magnetic conductive layer and a non-magnetic insulating layer.
According to a tenth aspect of the present invention, the injection junction of the spin injection part is capable of performing either spin preservation conduction or tunnel junction for spin-polarized electrons.
An eleventh aspect of the present invention is characterized in that the spin polarization part of the spin injection part is a ferromagnetic layer.
A twelfth aspect of the present invention is characterized in that the spin polarization part of the spin injection part is provided in contact with the antiferromagnetic layer for fixing the spin of the ferromagnetic layer.
According to a thirteenth aspect of the present invention, the aspect ratio of the first magnetic layer and the second magnetic layer of the free layer joined to the injection junction of the spin injection part is 2 or less.
The invention according to claim 14 is characterized in that the injection junction of the spin injection part is a word line.

  In the spin injection magnetic device having this configuration, when the spin is injected, the magnetization reversal of the free layer occurs and becomes parallel or anti-parallel to the magnetization of the fixed layer, so that a tunnel magnetoresistance effect appears. Therefore, the spin injection magnetic device of the present invention can cause the magnetization reversal of the free layer by spin injection at a smaller current density.

In the spin injection device of the present invention, the invention according to claim 15 is provided in contact with the spin injection unit including the spin polarization unit including the ferromagnetic fixed layer and the injection junction of the nonmagnetic layer, and the spin injection unit. A non-magnetic layer comprising an insulator or a conductor, a non-magnetic layer provided on a surface of the ferromagnetic free layer, and a current flowing in a direction perpendicular to a film surface of the spin injection device. And reverses the magnetization of the ferromagnetic free layer.
According to a sixteenth aspect of the present invention, the ferromagnetic free layer is Co or a Co alloy, the nonmagnetic layer provided on the surface of the ferromagnetic free layer is a Ru layer, and has a thickness of 0.1 to 20 nm. It is characterized by.
Further, in the spin injection device of the present invention, the invention according to claim 17 is characterized in that a spin injection portion composed of a spin polarization portion including a ferromagnetic fixed layer and an injection junction portion of a nonmagnetic layer is in contact with the spin injection portion. A non-magnetic layer comprising an insulator or a conductor, wherein the non-magnetic layer and the ferromagnetic layer are provided on the surface of the ferromagnetic free layer; A current is caused to flow in the direction perpendicular to the film surface to invert the magnetization of the ferromagnetic free layer.
In the invention according to claim 18, the ferromagnetic free layer and the ferromagnetic layer are Co or a Co alloy, the nonmagnetic layer provided on the surface of the ferromagnetic free layer is a Ru layer, and the film thickness is 2 to 20 nm. There is a feature.

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

  According to a nineteenth aspect of the present invention, which is a spin injection magnetic device of the present invention, the spin injection device according to any one of the fifteenth to eighteenth aspects is used. In the spin injection magnetic device of this configuration, when 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, so that a giant magnetoresistance effect or a tunnel magnetoresistance effect appears. . Therefore, the spin injection magnetic device of the present invention can cause the magnetization reversal of the ferromagnetic free layer by spin injection at a smaller current density.

  According to a twenty-fifth aspect of the present invention, which is a spin injection magnetic memory device of the present invention, the spin injection device according to any one of the fifteenth to eighteenth aspects is used. 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. I 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 at a smaller current density.

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

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. The same reference numerals are used for the same or corresponding members in each drawing.
1A and 1B are conceptual diagrams of a spin injection device of the present invention, in which FIG. 1A is a conceptual diagram showing a state in which the spin of SyAF is directed downward, and FIG. 1B is a conceptual diagram showing a state in which the spin of SyAF is directed upward by spin injection.

As shown in FIG. 1, a spin injection device 10 according to the present invention includes a first spin injection unit 1 having a spin polarization unit 9 and an injection junction 7 and a first nonmagnetic layer 2 that is antiferromagnetically coupled. The magnetic layer 4 and the second magnetic layer 6 include SyAF3 forming a three-layer structure, and these form a stacked structure.
First, SyAF3 according to the present invention will be described.
The magnetic field Hsw required for the magnetization reversal of the ferromagnetic single layer film 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 a single magnetic domain structure is similarly formed, the magnetization reversal magnetic field of SyAF having the thicknesses t ₁ and t _{2 of the} two ferromagnetic layers and the saturation magnetizations M ₁ and M ₂ 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 ), and w is the width of SyAF.

In the above equations (2) and (3), C (k) is a demagnetizing factor dependent on the aspect ratio k, and decreases as k approaches 1, and C (k) = 0 when k = 1. . 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, since the second term generally exceeds the first term in both Equations (2) and (3), and ΔM <Ms, the magnetization reversal magnetic field of SyAF is smaller than that of SyAF when w is the same. Become smaller. On the other hand, since C (k) becomes zero when k = 1, the magnetization reversal magnetic field is determined by the first term of Expressions (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 magnetic field is not given by Expression (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 the SyAF according to the present invention, a single magnetic domain structure is obtained even when k ≦ 2, especially k = 1. As a result, the SyAF according to the present invention can obtain a smaller magnetization reversal magnetic field. In particular, in a device with k = 1, the magnetization reversal magnetic field does not depend on the device size. The present invention is based on this finding, and by injecting spin-polarized electrons into SyAF, magnetization reversal can be realized with a smaller current density. In particular, when k = 1, C (k) becomes zero, so that the magnetization reversal magnetic field becomes extremely small.

  Referring to FIGS. 1A and 1B, the SyAF 3 according to the present invention includes two magnetic layers of a first magnetic layer 4 and a second magnetic layer 6 via a non-magnetic layer 2. Have a three-layer structure magnetically coupled antiparallel to each other, and each film is formed in a nanometer size. By spin-injecting the SyAF 3 from the spin polarization section 9 of the ferromagnetic layer via the injection junction 7 of the nonmagnetic metal layer of the spin injection section 1, the magnetization reversal of the SyAF 3 is realized.

  The non-magnetic layer 2 is a substance that couples the magnetizations of the two magnetic layers through this to antiferromagnetically. 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 indicate terminals through which current flows. Since the ferromagnetic layer and the magnetic layer are conductors, they can also be used as electrodes, but a separate electrode may be provided to allow current to flow.

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 the antiparallel state. I have. That is, the magnetization of the first magnetic layer 4 and the magnetization of the second magnetic layer 6 have antiparallel states of different magnitudes, that is, antiparallel spins of different magnitudes.
Assuming that 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 set to the spin direction ↑ or ↓ of SyAF 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 the SyAF 3, t ₁ M ₁ and t ₂ M ₂ may be different.

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 stacked, and the injection junction part 7 of the nonmagnetic conductive layer has a nanometer size. Here, the nanometer size means a size that an electron can conduct while preserving its momentum and spin. In other words, the injection junction 7 has a size capable of spin-conserving conduction.
In the case of metal, the mean free path of electrons is 1 μm or less, and in an element having a size of 1 μm or less, the injected spin can flow into the other without relaxation.
The injection junction 7 of the spin injection unit 1 may be a non-magnetic insulating layer 12, as shown in FIG. The non-magnetic insulating layer 12 has a nanometer size that is large enough to allow a tunnel junction through which a tunnel current flows, and is several nm.

  Although the spin-polarized portion 9 made of a ferromagnetic layer is a ferromagnetic material, the number of up-spin electrons and the number of down-spin electrons on the Fermi surface that are responsible for conduction are different. The 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 mA or less is passed from the spin-polarized portion 9 of the ferromagnetic layer to the non-magnetic metal layer (or the non-magnetic metal layer) in the direction perpendicular to the film plane. When spin injection is performed through the injection junction 7 of the magnetic insulating layer 12), the magnetization of the SyAF 3 is reversed while the spin of the magnetic layer 4 and the spin of the magnetic layer 6 are maintained in an antiparallel state. Therefore, in the spin injection device of the present invention, magnetization reversal by spin injection can be performed with a smaller current density. As a result, spin injection magnetization reversal can be performed only by applying a minute current without applying 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 according to the spin injection device of the present invention. Referring to FIG. 3, this embodiment has a structure in which the spin polarization section 9 has an antiferromagnetic layer 21 and a ferromagnetic layer 23. , The spin of the ferromagnetic layer 23 is fixed. The injection junction is the nonmagnetic metal layer 25 capable of spin-conserving conduction, and an insulating layer capable of tunnel junction may be used instead. In such a configuration, the spin of the spin-polarized portion is fixed and the spin is injected, so that the magnetization reversal of SyAF can be performed.

Next, a third embodiment will be described. FIG. 4 is a schematic view showing a spin injection device according to the third embodiment. Referring to FIG. 4, the spin injection device 14 includes a spin polarization section 9 including an antiferromagnetic layer 21 and a ferromagnetic pinned layer 26, and a nonmagnetic layer serving as an injection junction provided in contact with the ferromagnetic pinned layer. It has a two-layer structure including a layer 7 and a ferromagnetic free layer 27 and a nonmagnetic layer 28 on the nonmagnetic layer 7.
The spin injection section 1 includes a spin polarization section 9 and an injection junction section 7. In the spin polarization section 9, the antiferromagnetic layer 21 is brought close to the ferromagnetic fixed layer 26 so that The spin is fixed.
The injection junction 7 is a non-magnetic metal layer 25 such as Cu capable of spin-conserving conduction, 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 at the interface with the ferromagnetic free layer 27 to reflect a majority (majority) spin and transmit a minority (minority) spin. Therefore, the film thickness of the nonmagnetic layer 28 may be set to a distance within which a small number of spins can move while keeping the spins, that is, the spin diffusion length.
Here, as the ferromagnetic free layer 27, Co or a Co alloy can be used. As the non-magnetic layer 28, Ru, Ir, Rh can be used, and it is particularly preferable to use Ru. It is known that the spin diffusion length of Ru is 14 nm, and the thickness of Ru may be 0.1 nm to 20 nm. The following description is based on the assumption 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 illustrating the magnetization reversal of the spin injection device 14 according to the third embodiment. In FIG. 5, when electrons are injected from the ferromagnetic pinned layer 26 to the ferromagnetic free layer 27, a large number of spin electrons 17 apply a torque 18 so that the magnetization of the ferromagnetic free layer 27 is aligned with the magnetization of the ferromagnetic pinned layer 26. give. At this time, it is known that many spin electrons are strongly scattered (reflected) and few spin electrons are not scattered (transmitted) at the interface between Co or the Co alloy 27 and Ru 28.
Therefore, as shown in FIG. 5, the majority spin electrons 19 reflected at the interface between the Co or Co alloy 27 and the Ru 28 can be obtained if the thickness of the Co or Co alloy 27 is small enough to maintain the spin conduction. The reflected multiple spin electrons 19 also apply a similar torque 18 ′ to the ferromagnetic free layer 27. As a result, the torque of the ferromagnetic free layer 27 substantially increases, and becomes the same direction as the magnetization of the ferromagnetic fixed layer 26.

  On the other hand, when the direction of the 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 Co. The minority spin electrons are injected into the ferromagnetic free layer 27 made of a Co alloy, and apply a torque to the spins of the ferromagnetic free layer 27 so as to align the spins in the same direction, that is, downward. Thereby, the torque due to the few 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 fixed layer 26. As described above, according to the spin injection device 14 of the present invention, by inserting the nonmagnetic layer 28, the spin of the spin polarization section 9 is fixed and the spin injection is performed, and the magnetization reversal of the ferromagnetic free layer 27 is performed by the conventional spin injection. It can be performed at a lower current density than the magnetization reversal.

Further, a spin injection device according to a fourth embodiment will be described with reference to FIG. The spin injection device 16 of this embodiment differs from the spin injection device 14 shown in FIG. 4 in that a ferromagnetic fixed 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, the thickness of the nonmagnetic layer 28 is determined so that the magnetization of the ferromagnetic free layer 27 and the ferromagnetic fixed layer 29 are not antiparallel as in SyAF3 and spin-conservative conduction occurs. Just fine. Therefore, when Co or a Co alloy is used for the ferromagnetic free layer 27 and the ferromagnetic fixed layer 29 and Ru is used for 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 according to the fourth embodiment will be described.
In FIG. 6, when electrons are injected from the ferromagnetic fixed layer 26 to the ferromagnetic free layer 27, as in the spin injection device 14 of the third embodiment, the ferromagnetic free layer 27 made of Co or a Co alloy is removed. The magnetization is in the same direction as the magnetization of the ferromagnetic fixed layer 26.

On the other hand, a case where the direction of the current is given in reverse will be described with reference to FIG.
FIG. 7 is a schematic diagram illustrating the magnetization reversal of the spin injection device 16 according to the fourth embodiment. In FIG. 7, when electrons are injected from the ferromagnetic fixed layer 29 to the ferromagnetic free layer 27, a large number of spin electrons 37 are strongly reflected at the interface between the ferromagnetic fixed layer 29 and the Ru layer 28, and Does not reach. At this time, if the thickness of the Co or Co alloy 27 is small enough to maintain the spin conduction, the few spin electrons 39 are not scattered and reach the ferromagnetic free layer 27, and the spin of the ferromagnetic free layer 27 Are applied so that Therefore, the magnetization of the ferromagnetic free layer 27 is antiparallel to the ferromagnetic fixed layer 26. Thus, the large number of spin electrons 37 do not reach the ferromagnetic free layer 27 as compared with the case where the Ru layer 28 is not provided, and the magnetization reversal can be performed with a smaller current density.
As described above, according to the spin injection device 16 of the present embodiment, the spin of the spin polarization section 9 is fixed and the spin is injected, and the ferromagnetic free layer 27, the nonmagnetic layer 28, and the ferromagnetic pinned layer used instead of the SyAF3 are used. In the layer 29, the magnetization reversal of the ferromagnetic free layer 27 can be performed at a low current density.

  In the spin injection device, when the magnetization reversal of the ferromagnetic free layer 27 occurs, the magnetization becomes parallel or anti-parallel to the magnetization of the ferromagnetic fixed layer 26, so that the antiferromagnetic layer 21, the ferromagnetic fixed layer 26, The layer structure including the injection junction 7 made of the non-magnetic metal layer 25 and the ferromagnetic free layer 27 produces a giant magnetoresistance effect as in the case of the CPP type giant magnetoresistance element. 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 antiferromagnetic layer 21 and the ferromagnetic fixed layer 26 are connected to the insulating layer 12 capable of tunnel junction. The layer structure including the ferromagnetic free layer 27 produces a tunnel magnetoresistive effect, similarly to 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 device of the present invention. The spin injection magnetic device 30 includes a ferromagnetic spin tunnel junction (MTJ) element 36 in which a SyAF 3 serving as a free layer and a fixed layer 31 composed of a ferromagnetic layer 32 and an antiferromagnetic layer 34 are tunnel-juncted with an insulating layer 33. The MTJ element 36 includes a spin injection unit 1 for reversing the magnetization of a free layer that is a ferromagnetic layer. The spin injection part 1 has an injection junction formed by an insulating layer 12 capable of tunnel junction.

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

In the spin injection magnetic device, SyAF3 is replaced with a two-layer structure including 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 may be configured.
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 composition replaced with three-layer structure.

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

In such a spin injection magnetic device, the free layer SyAF is sandwiched or covered with an insulating film capable of tunnel junction, and the spin injection portion corresponding to the SyAF is coupled as a word line and finely processed to form a fixed layer side. By connecting a bit line to the ferromagnetic layer and performing fine processing, a basic structure of an MRAM or a spin injection magnetic memory device can be obtained.
Here, the free layer is formed of a two-layer structure including a ferromagnetic free layer 27 and a nonmagnetic layer 28 or a ferromagnetic layer 29 provided on the nonmagnetic layer 28 and the nonmagnetic layer, in addition to SyAF. Can be used.

Next, a magnetic thin film that can be used in the spin injection device and the spin injection magnetic device of the present invention will be described.
FIG. 9 is a sectional view of a magnetic thin film that can be used in the present invention. As shown in FIG. 9, a magnetic thin film 41 has a Co ₂ Fe _x Cr _1-x Al thin film 43 disposed on a substrate 42 at room temperature. Here, 0 ≦ x ≦ 1.
The Co ₂ Fe _x Cr _1-x Al thin film 43 is ferromagnetic at room temperature, has an electric resistivity of about 190 μΩ · cm, and has any one of the L2 ₁ , B2, and A2 structures without heating the substrate. It has two structures.
Further, by heating the substrate on which the Co ₂ Fe _x Cr _1-x Al thin film 43 is disposed, it is easy to obtain the L _{2 1} structure Co ₂ F _x Cr _1-x Al thin film 43 having a large spin polarizability. Here, the thickness of the Co ₂ Fe _x Cr _1-x Al thin film 43 on the substrate 42 may be 1 nm or more and 1 μm or less.

FIG. 10 is a 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 is the same as the magnetic thin film 41 shown in FIG. 9 except that a buffer layer is further provided between the substrate 42 and the Co ₂ F _x Cr _1-x Al (where 0 ≦ x ≦ 1) thin film 43. 44 is inserted. By inserting the buffer layer 44, the crystallinity of the Co ₂ F _x Cr _1-x Al (here, 0 ≦ x ≦ 1) thin film 43 on the substrate 41 can be further improved.

As the substrate 42 used for the magnetic thin films 41 and 45, a polycrystal such as thermally oxidized Si or glass, or a single crystal such as MgO, Al ₂ O ₃ or GaAs can be used. Further, as the buffer layer 44, Al, Cu, Cr, Fe, Nb, Ni, Ta, NiFe, or the like can be used.
The thickness of the Co ₂ Fe _x Cr _1-x Al (here, 0 ≦ x ≦ 1) thin film 43 may be 1 nm or more and 1 μm or less. If this film thickness is less than 1 nm, it will be difficult to obtain substantially any one of the L2 ₁ , B2, and A2 structures described later, and if this film thickness exceeds 1 μm, application as a spin injection device will be difficult. It is 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 F _x Cr _1-x Al (here, 0 ≦ x ≦ 1) used for the magnetic thin film. The structure shown in the figure shows a structure that is eight times (double the lattice constant) the conventional unit cell of bcc (body-centered cubic lattice).
In the L2 ₁ structure of Co ₂ Fe _x Cr _1-x Al, the composition ratio of Fe and Cr is F _x Cr _1-x (where 0 ≦ x ≦ 1) at the position I in FIG. Al is placed at the position II, and Co is placed at the positions III and IV.
Further, the B2 structure of Co ₂ Fe _x Cr _1-x Al has a structure in which Fe, Cr and Al are irregularly arranged at positions I and II in FIG. In this case, the composition ratio of Fe and Cr is set so as to _satisfy FexCr1 _-x (where 0≤x≤1).
Further, the A2 structure of Co ₂ Fe _x Cr _1-x Al has a structure in which Co, Fe, Cr and Al are irregularly substituted. In this case, the composition ratio of Fe and Cr is set so as to _satisfy FexCr1 _-x (where 0≤x≤1).

Next, the magnetic properties of the magnetic thin films 41 and 45 having the above configuration will be described.
The Co ₂ Fe _x Cr _1-x Al (here, 0 ≦ x ≦ 1) thin film 43 having the above structure is ferromagnetic at room temperature and has any of the L2 ₁ , B2, and A2 structures without heating the substrate. A Co ₂ Fe _x Cr _1-x Al thin film having one structure is obtained.
Further, the Co ₂ Fe _x Cr _1-x Al thin film 43 (here, 0 ≦ x ≦ 1) having any one of the L2 ₁ , B2, and A2 structures even in a very thin film having a thickness of about several nm. One structure is obtained.
Here, the B2 structure of the Co ₂ Fe _x Cr _1-x Al (here, 0 ≦ x ≦ 1) thin film is a unique substance that has not been obtained conventionally. The B2 structure is similar to the L2 ₁ structure, except that in the L2 ₁ structure, Cr (Fe) and Al atoms are regularly arranged, whereas the B2 structure is irregularly arranged. That is. The A2 structure is a structure in which Co, Fe, Cr and Al are irregularly substituted. These differences can be measured by X-ray diffraction.
In 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 be. When 0.8 ≦ x ≦ 1.0, an A2 structure is obtained.
Further, in the composition x, within a range of 0 ≦ x ≦ 1, a Co ₂ Fe _x Cr _1-x Al thin film is formed on a heated substrate, or a heat treatment is performed after forming the film without heating the substrate. , L2 ₁ or B2 structures are obtained.

It is difficult to experimentally clarify that the magnetic thin films 41 and 45 having the above configuration are half-metals. However, qualitatively, a tunnel magnetoresistive effect element having a tunnel junction is manufactured and the tunnel magnetoresistive effect element exceeds 100%. If a very large TMR is shown, it can be considered to be half-metallic.
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 polarization of 0.5 is used for the other ferromagnetic layer of the insulating film. As a result, a large TMR exceeding 100% was obtained.

This indicates that the Co ₂ F _x Cr _1-x Al (0 ≦ x ≦ 1) thin film 43 has a spin polarizability of P = 0.7 or more in consideration of the equation (1). The reason why such a large TMR can be obtained is that the Co ₂ F _x Cr _1-x Al (0 ≦ x ≦ 1) thin film 3 has a large spin polarizability, Based on the discovery that any one of the ₁ , B2 and A2 structures can be obtained.
Thus, according to the magnetic thin films 41 and 45, it is not necessary to heat the substrate, and the Co ₂ F _x Cr _1-x Al (0 ≦ x ≦ 1) thin film 43 can obtain ferromagnetic characteristics with a thickness of 1 nm or more. Can be. This is because the surface of the tunnel junction can be made clean and sharp without oxidizing the surface or increasing the surface roughness. It is presumed that a large TMR can be obtained.

  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, or the ferromagnetic layer 9 of the spin injection part. The magnetic thin films 41 and 45 are formed 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. A tunnel magnetoresistive element having a CPP type giant magnetoresistive element structure or a layered structure including 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 construction. Further, it can be used for the ferromagnetic layer of the MTJ element or the tunnel magnetoresistive element used in the spin injection magnetic device of the present invention.

Next, a first embodiment 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 layer made of Ta and Cu on the thermally oxidized Si substrate and the uppermost layer is a layer to be an electrode. The IrMn layer and the Co ₉₀ Fe ₁₀ layer are the spin-polarized portions 9 including the antiferromagnetic layer 21 and the ferromagnetic fixed layer 26, respectively. Cu is the injection joint 7. The Co alloys Co ₉₀ Fe ₁₀ and Ru are the ferromagnetic free layer 27 and the non-magnetic layer 28 disposed on Cu of the non-magnetic layer 7.
Next, this film was finely processed by 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 fixed 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 bring it into an antiparallel state, that is, an initial state with high resistance. The external magnetic field H at this time is 50 Oe (Oersted) (see FIG. 12A).
As is clear from the figure, when a current is passed from the high resistance state of the small current indicated by A to about 5 mA indicated by B in the positive direction, the resistance sharply decreases and the magnetization is reversed. Further, it can be seen that this low resistance state is maintained even when the current is increased to 20 mA (see BC in FIG. 12).
Next, when the current is reduced and further applied in the negative direction, the resistance is kept low until about -7.5 mA (see C to D in FIG. 12). It can be seen that when a negative current larger than that is applied, the state again becomes a high resistance state and the magnetization is reversed (see EF in FIG. 12). The current density required for this magnetization reversal was 2.4 × 10 ⁷ A / cm ² , which was about 1/10 as compared with a comparative example described later. The magnetoresistance (MR) was 0.97% as shown in the drawing, and the same value as the magnetoresistance in the spin inversion structure of the comparative example described later was obtained.
Thus, in the spin injection device 14 of the first embodiment, the resistance of the ferromagnetic free layer 27 can be changed by changing the direction of the current flowing through the device and causing the magnetization reversal of the ferromagnetic free layer 27 to occur.

Next, a second embodiment will be described. The second embodiment 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 sequentially sputtered.
Here, the layer made of Ta and Cu on the thermally oxidized Si substrate and the uppermost layer is a layer to be an electrode. The IrMn layer and the Co ₉₀ Fe ₁₀ layer are the spin polarization sections 9 each composed of the antiferromagnetic layer 21 and the ferromagnetic fixed layer 26. Cu is the injection joint 7. The Co alloys Co ₉₀ Fe ₁₀ , Ru, and Co ₉₀ Fe ₁₀ are a ferromagnetic free layer 27, a nonmagnetic layer 28, and a ferromagnetic layer 29 disposed on Cu of the nonmagnetic layer 7, respectively.

The spin injection device 16 according to the second embodiment differs from the spin injection device 14 according to the first embodiment in that the thickness of Ru 28 on Co ₉₀ Fe ₁₀ 27 is increased from 0.45 nm to 6 nm, and that the ferromagnetic layer 29 That is, a Co ₉₀ Fe ₁₀ layer 29 having a thickness of 5 nm is provided.
Next, a spin injection device 16 having an element size of 100 × 100 nm ² was manufactured in the same manner as in Example 1.

FIG. 13 is a diagram illustrating the spin transfer magnetization reversal of the spin transfer device 16 of the second embodiment 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 fixed 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 make the initial state of high resistance is 150 Oe.
As is clear from the drawing, the resistance of the spin injection device 16 according to the second embodiment changes when the current is ± 0.2 mA similarly to the spin injection device 14 according to the first embodiment, and magnetization reversal occurs. 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 Comparative Example described later. The magnetoresistance was about 1%, and the same value as the magnetoresistance (MR) of the comparative example described later was obtained. As described above, by setting the thickness of Ru, which is the nonmagnetic layer 28, to 6 nm, the current density required for magnetization reversal could be reduced.

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

As a result of examining the cross section of this film using a transmission electron microscope, it was found that 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 that the particles had a double tunnel structure using SiO ₂ as an insulating matrix. With respect to this structure, a voltage was applied between the upper and lower Cu and Ta films to flow a current, and the resistance at that time was measured at room temperature while changing the current. As a result, a jump in resistance was observed at about 0.1 mA. . This is due to the appearance 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.
The comparative example has a structure in which 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, as a structure without a Ru layer in the spin injection device 14 of the first embodiment, Ta (2 nm) / Cu (20 nm) / IrMn (10 nm) / Co ₉₀ Fe ₁₀ (5 nm) / Cu (6 nm) are 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 in the} same manner as in Example 1.

FIG. 14 is a diagram showing (a) a magnetoresistance curve and (b) spin transfer magnetization reversal of a comparative example 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 from an external magnetic field of 0 (see G in FIG. 14A).
As is apparent from FIG. 14A, the magnetoresistance (MR) of the comparative example is 1.1%, which is the same value as the value reported conventionally. In FIG. 14B, the horizontal axis represents the current (mA) when the current flows from the second ferromagnetic layer 63 to the first ferromagnetic layer 61 in the positive direction, and the vertical axis represents the current. The resistance (Ω) at the time is shown. As is clear from FIG. 14 (b), by changing the current from positive to negative in the direction of the arrow from almost 0, magnetization reversal was developed in the same manner as in Example 1 (K to K in FIG. 14 (b)). L). The magnetoresistance was 0.98%, and the current density required for magnetization reversal was 2.4 × 10 ⁸ A / cm ² .

Next, comparison between the example and the comparative example will be described.
In the example, the current density required for the magnetization reversal was lower than in the comparative example. In particular, when the thickness of the Ru layer 28 is in the range of 2 to 20 nm as in the second embodiment, 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 it can be reduced to

  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 they are also included in the scope of the present invention. .

It is a conceptual diagram of a spin injection device of a first embodiment of the present invention, (a) is a conceptual diagram showing a state in which the spin of SyAF is downward, and (b) is a conceptual diagram showing a state in which the spin of SyAF is upward by spin injection. It is. 1 is a schematic view of a spin injection device according to a first embodiment in which an injection junction is a nonmagnetic insulating layer. FIG. 4 is a schematic view showing a second embodiment of the spin injection device of the present invention. FIG. 7 is a schematic view showing a third embodiment of the spin injection device of the present invention. FIG. 9 is a schematic diagram illustrating magnetization reversal of a spin injection device according to a third embodiment. FIG. 9 is a schematic view showing a fourth embodiment of the spin injection device of the present invention. FIG. 14 is a schematic diagram illustrating magnetization reversal of the spin injection device according to the fourth embodiment. 1 is a schematic view of a spin injection magnetic device according to the present invention. FIG. 2 is a sectional view of a magnetic thin film that can be used in the present 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. FIG. 4 is a diagram illustrating the spin injection magnetization reversal of the spin injection device of Example 1 at room temperature. FIG. 9 is a diagram illustrating the spin injection magnetization reversal of the spin injection device of Example 2 at room temperature. It is a figure which shows the (a) magnetoresistance curve of the comparative example at room temperature, and (b) spin injection magnetization reversal. It is a schematic diagram showing the principle of conventional spin magnetization reversal.

Explanation of reference numerals

1: spin injection part 2: non-magnetic layer 3: SyAF
4: First magnetic layer 6: Second magnetic layer 7: Injection junction 9: Spin polarizer 10, 14, 16: Spin injection device 12: Non-magnetic insulating layer 17, 37: Many 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 Non-magnetic layer 29 provided on layer: Ferromagnetic layer 30 provided on non-magnetic layer 30: Spin injection magnetic device 31: Fixed layer 32: Ferromagnetic layer 33: Insulating layer 36: MTJ element 39: Small number of spin electrons 41, 45: Magnetic thin film 42: Substrate 43: Co ₂ F _x Cr _1-x Al thin film 44: Buffer layer

Claims (20)

A spin injection unit having a spin polarization unit and an injection junction,
A SyAF having a first magnetic layer and a second magnetic layer having different magnitudes of magnetization magnetically coupled antiparallel via a nonmagnetic layer,
The SyAF and the injection joint are joined,
A spin injection device in which spin-polarized electrons are injected from the spin injection section and the magnetization of the first magnetic layer and the second magnetic layer is reversed while maintaining the antiparallel state.   The spin injection device according to claim 1, wherein an injection junction of the spin injection unit is one of a nonmagnetic conductive layer and a nonmagnetic insulating layer.   3. The spin injection device according to claim 1, wherein an injection junction of the spin injection unit is one of spin preserving conduction and tunnel junction permissible for the spin-polarized electrons. 4.   The spin injection device according to claim 1, wherein the spin polarization section of the spin injection section is a ferromagnetic layer.   4. The spin injection device according to claim 1, wherein the spin polarization section of the spin injection section is provided in contact with an antiferromagnetic layer for fixing a spin of the ferromagnetic layer. 5.   The spin according to claim 1, wherein an aspect ratio of the first magnetic layer and the second magnetic layer of SyAF joined to the injection junction of the spin injection unit is 2 or less. Infusion device. A first magnetic layer and a second magnetic layer having different magnetization magnitudes that are magnetically coupled antiparallel via a nonmagnetic layer, and the magnetizations of the first magnetic layer and the second magnetic layer are A free layer capable of reversing magnetization while maintaining an antiparallel state,
A ferromagnetic fixed layer tunnel-joined via the free layer and an insulating layer,
A spin injection magnetic device, wherein the ferromagnetic pinned layer and the free layer have a ferromagnetic spin tunnel junction.   8. The spin injection magnetic device according to claim 7, further comprising a spin injection part having an injection junction part and a spin polarization part joined to the free layer, in addition to the configuration.   9. The spin injection magnetic device according to claim 8, wherein the injection junction of the spin injection unit is one of a nonmagnetic conductive layer and a nonmagnetic insulating layer.   10. The spin injection magnetic device according to claim 8, wherein an injection junction of the spin injection unit is capable of performing spin preservation conduction and tunnel junction with respect to the spin-polarized electrons. 11.   The spin injection magnetic device according to claim 8, wherein the spin polarization part of the spin injection part is a ferromagnetic layer.   The spin injection magnetic device according to claim 8, wherein the spin polarization section of the spin injection section is provided in contact with an antiferromagnetic layer for fixing a spin of the ferromagnetic layer.   The aspect ratio of the first magnetic layer and the second magnetic layer of the free layer joined to the injection junction of the spin injection unit is 2 or less, according to claim 7. Spin injection magnetic device.   14. The spin injection magnetic device according to claim 8, wherein the spin injection unit is a word line. In a spin injection device including a spin injection portion including a spin polarization portion including a ferromagnetic fixed layer and an injection junction of a nonmagnetic layer, and a ferromagnetic free layer provided in contact with the spin injection portion,
The non-magnetic layer is made of an insulator or a conductor, a non-magnetic layer is provided on the surface of the ferromagnetic free layer, and a current flows in a direction perpendicular to the film surface of the spin injection device to change the magnetization of the ferromagnetic free layer. A spin injection device characterized by being inverted.   The ferromagnetic free layer is made of Co or a Co alloy, the nonmagnetic layer provided on the surface of the ferromagnetic free layer is a Ru layer, and has a thickness of 0.1 to 20 nm. Item 16. A spin injection device according to Item 15. A spin injection device including: a spin injection unit including a spin polarization unit including a ferromagnetic fixed layer and an injection junction of a nonmagnetic layer; and a ferromagnetic free layer provided in contact with the spin injection unit.
The non-magnetic layer is made of an insulator or a conductor,
A nonmagnetic layer and a ferromagnetic layer are provided on the surface of the ferromagnetic free layer,
A spin injection device, characterized in that a current flows in a direction perpendicular to the film surface of the spin injection device to reverse the magnetization of the ferromagnetic free layer.   The ferromagnetic free layer and the ferromagnetic layer are made of Co or a Co alloy, the nonmagnetic layer provided on the surface of the ferromagnetic free layer is a Ru layer, and has a thickness of 2 to 20 nm. The spin injection device according to claim 17, wherein:   A spin-injection magnetic apparatus using the spin-injection device according to claim 15.   A spin injection magnetic memory device using the spin injection device according to any one of claims 15 to 18.

Images