JP2014086448A - Spintronics device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spintronics device in which a spin current-current conversion efficiency specified by a spin current-current conversion coefficient αhaving a spin current-electron mutual conversion member is made not less than α.SOLUTION: As a spin current-electron mutual conversion member layer joined to a spin current generating member layer, a conductive member in the electric conductivity in an inflow direction of a spin current is used which is higher than that in the electric conductivity in the other direction.

Description

  The present invention relates to a spintronic device, and for example, relates to a spintronic device in which spin current-current conversion efficiency is increased by using a member having anisotropic conductivity as an inverse spin Hall effect member.

  In the current electronics field such as semiconductor devices, the degree of freedom of charge of electrons is used, but electrons have the degree of freedom of spin in addition to charges. In recent years, spintronics using this degree of freedom of spin has been attracting attention as a leader of next-generation information technology.

  This spintronics aims to obtain unprecedented functions and characteristics by simultaneously using the charge of electrons and the degree of freedom of spin, but many of the spintronic functions are driven by spin current.

  Since the spin current has little energy dissipation, it is expected that it can be used for efficient energy transfer, and there is an urgent need to establish a spin current generation method and detection method. As a method of generating a spin current, a spin current by spin pumping has been proposed (see, for example, Non-Patent Document 1), and a spin current detection method is also proposed by the present inventors by using the inverse spin Hall effect (ISHE). It has been proposed to convert a current into a current and take it out as a voltage (see, for example, Non-Patent Document 2).

The reverse spin Hall effect member used for obtaining such a reverse spin Hall effect is any one of an element having a transition metal having Pt, Au, Pd, Ag, Bi, f orbital or 3d orbital, or an alloy thereof. Or an alloy of Cu, Al, or Si with the above-mentioned materials, and Pt or Bi-doped Cu having high reverse spin Hall effect generation efficiency is particularly promising. In addition, when an external magnetic field is applied to the reverse spin Hall effect member, a reverse spin Hall voltage _EISHE is generated in a direction orthogonal to the external magnetic field.

The motion of electrons in the spin Hall effect or the inverse spin Hall effect is described by the Boltzmann equation expressed by the following equation (1).
Here, v _k is an electron velocity, f _kσ is an electron distribution function, e is an elementary charge, E is an external electric field, h is a Planck constant, h slash represents h / 2π, Is an electron scattering term due to impurities. Here, if k is the momentum of electrons and m is the mass of electrons,
V _k = (h / 2π) k / m.

The scattering term due to the impurity on the right side in the equation (1) is described by the following equation (2).
The left term in Equation (2) is the k′σ ′ momentum / spin state to the kσ momentum / spin state scattering term, and the right term is the kσ momentum / spin state to k′σ ′ momentum. -It is a scattering term to the spin state.

Further, a coefficient applied to the distribution function of the right term in the equation (2) is expressed by the following equation (3), and from the momentum / spin state (| kσ>) of kσ to the momentum / spin state (kσ ′) | K′σ ′>) represents the scattering probability.
In addition, n _imp in the formula is an impurity concentration, and T (with a mountain symbol) is a scattering matrix. The coefficient applied to the distribution function of the left term is also expressed by changing the position of “′”.

By solving this Boltzmann equation, the distribution f _kσ is described by the following equation (4).
In Equation (4), σ represents electrical conductivity, τ _tr represents scattering time due to impurities, μ (r) represents electrochemical potential, α _H represents spin current-current conversion coefficient, σ _σσ is a Pauli matrix representing the spin direction.

Α _H is expressed by the following formula (5).
In Equation (5), the η _SO bar represents a dimensionless spin-orbit coupling parameter, N (0) represents the density of states of electrons in the Fermi level, and V _imp represents the intensity of the impurity potential. The electrochemical potential μ is represented by the following formula (6).
Note that the arrow attached to μ means upspin or downspin. Also, ε _F is Fermi energy, φ is an electric potential, and φ = −− E.

Here, the spin current density j _s ^x in the x direction is represented by the following formula (7), and σ _x (general formula σ _i ) in the formula (7) is represented by the following formula (8).

The current density j _c converted from the spin current is expressed by the following formula (9), and the current j _c ^y flowing in the y direction accompanying the spin current in the x direction is expressed by the following formula (10). And finally,
^{_{j c y = α H · j}} s x
Next, the current density j _c ^y by inverse spin Hall effect spin current - will be defined in the current conversion coefficient alpha _H.

Therefore, in order to extract a large amount of current by the reverse spin Hall effect, it is important to use a substance having a large spin current-current conversion coefficient α _H as the reverse spin Hall effect member.

Phys. Rev. B19, p. 4382, 1979 Applied Physics Letters Vol. 88, p. 182509, 2006

As described above, the current j _c ^y by inverse spin Hall effect spin current - for that it will be defined in the current conversion coefficient alpha _H, to retrieve a number of current by the inverse spin Hall effect, large spin current - It is necessary to use a material having a current conversion coefficient α _H as an inverse spin Hall effect member.

However, the spin current-current conversion coefficient α _H of a material conventionally used as an inverse spin Hall effect member is about 10% of Pt at most, and about 25% can be expected even when Bi-doped Cu is used. Therefore, there is a limit in increasing the spin current-current conversion coefficient.

  Therefore, an object of the present invention is to further increase the spin current-current conversion efficiency.

  In order to solve the above problems, the present invention is a spintronic device, which is joined to a spin current generating member layer that generates a pure spin current or a spin wave spin current by supplying energy, and the spin current generating member layer, A spin current-current mutual conversion member layer that converts spin current into current or converts current into spin current, and provided in the spin current-current mutual conversion member layer, on the upstream side and the downstream side in the current flow direction. The spin current-current mutual conversion member layer has anisotropic conductivity in which the electrical conductivity in the inflow direction of the spin current is higher than the electrical conductivity in the other direction.

As a result of confirming the spin hole angle θ _SHE corresponding to the spin current-current conversion efficiency of various conductive materials by experiments, the present inventor found that θ _SHE = α _H in a normal conductor, In the case of a conductive material having a property, assuming that the electric conductivity in the inflow direction of the spin current is σ _x and the electric conductivity in the direction orthogonal thereto is σ _y , the spin hole angle θ _SHE is θ _SHE = (σ _y / Σ _x ) × α _H
I found out that Incidentally, in the case of a material having no anisotropic conductivity, σ _y = σ _x .

Therefore, by using a material having anisotropic conductivity of σ _y > σ _x as an inverse spin Hall effect member, a spin current-current conversion efficiency (spin hole angle θ _{SHE) of} about 10% defined by conventional α _H is used. ) Was newly found to be 100% or more. This also means that the conversion efficiency from current to spin current can be increased even in the spin Hall effect that converts current to spin current.

  Examples of spin current-current mutual conversion members such as reverse spin Hall effect members having anisotropic conductivity include conductive polymers, organic self-assembled films, organic charge transfer complex conductors, metal laminated films, and layered transition metals. Either an oxide or a three-dimensional topological insulator may be used.

  In particular, as the conductive polymer, PEDOT: PSS, which is a polymer obtained by mixing PEDOT [poly (3,4-ethylenedithiothiophene)] and PSS [poly (4-styreneenesulfonate)], or PBTT [poly (2,5- bis (3-alkylthiophene-2-yl) thieno [3,2-b] thiophene] and F4-TCNQ [2,3,5,6-tetrafluor-7,7,8,8-tetracyanoquinodimethane] And PBTTT: F4-TCNQ.

  When the spin current-current mutual conversion member layer having anisotropic conductivity is a reverse spin Hall effect member layer, the reverse spin Hall effect member layer is provided on the insulating substrate, and the magnetic layer is formed on the reverse spin Hall effect member layer. A layer may be provided. Alternatively, the magnetic layer may be provided on the insulating substrate, and the reverse spin Hall effect member layer having anisotropic conductivity may be provided on the magnetic layer.

According to the disclosed spintronic device, the spin current-current conversion efficiency, which has been conventionally defined by the spin current-current conversion coefficient α _H of the spin current-current mutual conversion member such as the inverse spin Hall effect member, is set to α _H or more. It becomes possible to do.

1 is a configuration explanatory diagram of a spintronic device according to an embodiment of the present invention. FIG. It is explanatory drawing of the manufacturing process of the spin current-current conversion element of Example 1 of this invention. It is a molecular structure diagram of PEDOT and PSS. 1 is a schematic perspective view of a spin current-current conversion element according to Example 1 of the present invention. It is a characteristic view at the time of applying a magnetic field to the H direction. It is a characteristic view at the time of applying a magnetic field to the -H direction. It is explanatory drawing of the absorption spectrum of a microwave, and the magnetic field strength dependence of the output voltage V. It is explanatory drawing of other various characteristics. It is explanatory drawing to the middle of the manufacturing process of the spin current-current conversion element of Example 2 of the present invention. It is explanatory drawing after FIG. 9 of the manufacturing process of the spin current-current conversion element of Example 2 of this invention. It is a schematic perspective view of the spin current-current conversion element of Example 2 of the present invention. It is explanatory drawing of the microwave absorption characteristic and output voltage of the spin current-current conversion element of Example 2 of this invention. It is explanatory drawing of the microwave frequency dependence of the resonant magnetic field strength _HFMR of the spin current-current conversion element of Example 2 of this invention, and the microwave frequency dependence of an output voltage. It is a schematic oblique view of the spin current-current conversion element of Example 3 of the present invention. It is a molecular structure diagram of PBTT and F4-TCNQ. It is explanatory drawing of the output characteristic of the spin current-current conversion element of Example 3 of this invention. It is explanatory drawing of the spin current-current conversion element of Example 4 of this invention. It is a schematic perspective view of the spin current-current conversion element of Example 5 of the present invention. It is a schematic perspective view of the spin current-current conversion element of Example 6 of the present invention. It is explanatory drawing of spin RAM of Example 7 of this invention.

  Here, a spintronic device according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a configuration explanatory diagram of a spintronic device according to an embodiment of the present invention. FIG. 1A is a conceptual perspective view of a spintronic device according to an embodiment of the present invention. FIG. It is a figure which shows the state of a spin current and an electric current.

As shown in FIG. 1A, a spin current-current mutual conversion member layer 2 having anisotropic conductivity is provided on an insulating substrate 1, and a pure spin current or a spin wave spin current is supplied thereon by supplying energy. And a pair of electrodes 4 ₁ and 4 ₂ are formed at both ends of the spin current-current mutual conversion member layer 2. In the test measurement, the voltmeter 6 is connected to the pair of electrodes 4 ₁ and 4 ₂ via the extraction electrodes 5 ₁ and 5 ₂ .

When this spintronic device is described as a spin current-current conversion element, spin pumping is performed by irradiating microwaves in a state in which a magnetic field is applied in a direction orthogonal to the pair of electrodes described above. A spin current j _s induced in a magnetic layer flows in the x direction, and a current j in the y direction is generated by spin-orbit interaction in the vicinity of the interface with the reverse spin Hall effect member layer which is the spin current-current mutual conversion member layer 2. _The electromotive force E _ISHE is output between the pair of electrodes 4 ₁ and 4 ₂ after being converted to _c .

The inventor of the present application has no spin-orbit interaction in the process of realizing a large spin current-current conversion efficiency. Therefore, even for an organic conductor in which the spin Hall angle θ _SHE is predicted to be close to 0, the reverse spin The Hall effect was verified. As a result, an unexpectedly large value of 0.042% or more was obtained while the spin hole angle θ _{SHE of} GaAs having strong spin-orbit interaction is about 0.1%.

As a result of intensive studies on this measurement result, the spin hole angle θ _SHE is not equal to α _H and equal, but the anisotropic conductivity of the inverse spin Hall effect member makes the electrical conductivity in the direction of flow of the spin current σ _x And the electrical conductivity in the direction of current flow is σ _y ,
θ _SHE = (σ _y / σ _x ) × α _H
It came to the conclusion that it is expressed by. Accordingly, it has been found that conversion efficiency of 100% or more can be achieved by using a material having anisotropic conductivity having a large value of σ _y / σ _x .

The insulating substrate 1 in this case may be anything as long as the surface is insulative. Examples thereof include a glass substrate, a silicon substrate provided with a SiO ₂ film on the surface, a sapphire substrate, and the like, and the spin current generating member layer 3 Is made a single crystal substrate such as GGG (Gd ₃ Ga ₅ O ₁₂ ).

When the spin current generating member layer 3 is a magnetic material layer, in principle, it may be a metal magnetic material such as Ni ₈₀ Fe ₂₀ , a magnetic semiconductor, or a magnetic dielectric. The magnetic dielectric material may be anything as long as it contains Fe or Co. However, garnet ferrite, spinel ferrite, or hexagonal ferrite, particularly practically, is easily available and has low dissipation of spin angular momentum. YIG (yttrium iron garnet) or yttrium gallium iron garnet, that is, garnet ferrite consisting of Y ₃ Fe _5-x Ga _x O ₁₂ (where 0 ≦ x <5) or YIG Y site It is desirable to use garnet ferrite substituted with atoms such as Bi, for example, Bi _x Y _3-x Fe ₅ O ₁₂ .

When a magnetic dielectric such as Y ₃ Fe _{5 -x} Ga _x O ₁₂ (where 0 ≦ x <5) is used as the magnetic layer, a sputtering method, a MOD method (Metal-organic decomposition method: organic) (Metal coating pyrolysis method), sol-gel method, liquid phase epitaxy method, floating zone method, or aerosol deposition method may be used. The crystallinity of the magnetic dielectric may be single crystal or polycrystal.

In the case of using the MOD method, for example, a MOD solution having a Y ₃ Fe ₄ GaO ₁₂ composition is applied on a GGG (Gd ₃ Ga ₅ O ₁₂ ) single crystal substrate by a spin coating method, for example. As spin coating conditions in this case, first, after rotating at 500 rpm for 5 seconds, rotating at 3000 to 4000 rpm for 30 seconds, the MOD solution is uniformly applied so that the film thickness after baking becomes 100 nm. As the MOD solution, for example, a MOD solution manufactured by Kojundo Chemical Laboratory Co., Ltd. is used.

  Next, for example, drying is performed on a hot plate heated to 150 ° C. for 5 minutes to evaporate excess organic solvent contained in the MOD solution, and then pre-baking is performed in an electric furnace, for example, at 550 ° C. for 5 minutes. To form an oxide layer.

  Next, in the main firing in which heating is performed at 750 ° C. for 1 to 2 hours in an electric furnace, crystallization of the oxide layer is advanced to form a YIG layer. Finally, the YIG layer may be cut out to a predetermined size.

In the case of using the aerosol deposition method, for example, Fe ₂ O ₃ , NiO, and ZnO having an average particle diameter of 1 μm are used, and aerosol powders of 50 mol%, 27 mol%, and 23 mol%, respectively, are used. What is necessary is just to deposit Ar gas used as carrier gas at 1000 sccm by spraying it onto the substrate using a nozzle of 0.4 mm × 10 mm.

  Further, the spin current generating member is not limited to a magnetic material, and any member that generates a pure spin current or a spin wave spin current by supplying energy may be used. For example, a semiconductor having a zinc blende crystal structure For example, GaAs or the like may be used. When a semiconductor having a zinc blende type crystal structure is excited by circularly polarized light having a slightly higher energy than the fundamental absorption edge of the semiconductor, spin-polarized electrons are excited from the valence band to the conduction band, resulting in a spin current. Occur.

  Further, when such a spin current-current mutual conversion member having anisotropic conductivity is used as a spin Hall effect member, the generated spin current can be increased. For example, the performance of a magnetic memory by magnetization switching can be increased. Can be increased.

  The spin current-current mutual conversion member having anisotropic conductivity includes conductive polymer, organic self-assembled film, organic charge transfer complex conductor, metal laminated film, layered transition metal oxide, or three-dimensional topological Any one of insulators may be used.

  As the conductive polymer, a π-conjugated polymer is preferable. This is because the electrons (holes) move through the π orbitals and thus have an electric conduction anisotropy due to the direction of the π orbitals. Examples of the π-conjugated polymer include aliphatic conjugated polymers such as polyacetylene, aromatic conjugated polymers such as polyparaphenylene, mixed conjugated polymers such as polyparaphenylene vinylene, polythiofin, polypyrrole, PEDOT [poly (3,4). -Ethylenediothiophene)] and the like, and two-dimensional conjugated polymers such as graphene. PEDOT: PSS in which polystyrene sulfonic acid (PSS: poly (4-styrenesulfonate)) is used as a polymer dopant and dispersed in water or an organic solvent is preferable because a conductive thin film can be formed by a simple method called spin coating. Instead of PSS, PVS (polyvinyl sulfonic acid) may be used. Alternatively, PBTT [poly (2,5-bis (3-alkylthiophen-2-yl) thieno [3,2-b] thiophene] and F4-TCNQ [2,3,5,6-tetrafluor-7,7, 8,8-tetracyanoquinodimethane].

The metal laminate film, include laminated structure film such as Pt / Cu / Pt / Cu ··· , La 2-x Sr x CuO 4 , and the like as the layered transition metal oxides. The three-dimensional topological insulator is an insulator, but the inside is only insulative, and the surface is a conductor.

  Further, the laminated structure of the elements is not limited to the structure shown in FIG. 1A, and the spin current generating member layer 3 is formed on the insulating substrate 1 and has anisotropic conductivity. The spin current-current mutual conversion member layer 2 may be formed.

In the embodiment of the present invention, since a member having anisotropic conductivity is used as the spin current-current mutual conversion member, the spin Hall angle θ _SHE is (σ _y / σ _x ) × α _H and is injected. The spin current can be converted into a current with a conversion efficiency of 100% or more. Further, when a current is injected from the spin current-current mutual conversion member layer 2 into the spin current generating member layer 3, the injected current can be converted into a spin current with a conversion efficiency of 100% or more.

  Here, with reference to FIG. 2 thru | or FIG. 8, the spin current-current conversion element of Example 1 of this invention is demonstrated. FIG. 2 is an explanatory diagram of a manufacturing process of the spin current-current conversion element according to the first embodiment of the present invention. First, as shown in FIG. 2A, PEDOT [poly (3,4) is formed on a glass substrate 11. -Ethylenedioxythiophene)] and PSS [poly (4-styrenesulfonate)] are mixed to form droplets, and the PEDOT: PSS film 12 is formed by spin coating.

Next, as shown in FIG. 2B, a Ni ₈₀ Fe ₂₀ film 13 having a size of 2.0 mm × 2.5 mm is deposited on the PEDOT: PSS coating 12 by using an electron beam evaporation method. Note that a sputtering method may be used instead of the electron beam evaporation method. Next, as shown in FIG. 2 (c), a pair of Au electrodes 14 ₁ with a detail of 2.0 mm × 0.5 mm is located at a position 500 μm away from the end of the Ni ₈₀ Fe ₂₀ film 13 using a mask vapor deposition method. , by forming a 14 _2, the spin current - the basic structure of the current converting element is completed.

  3 is a molecular structure diagram of PEDOT and PSS, FIG. 3 (a) is a molecular structure diagram of PEDOT, and FIG. 3 (b) is a molecular structure diagram of PSS. This PEDOT: PSS coating 12 has a spin-coated in-plane electrical conductivity that is much greater than the electrical conductivity in the film thickness direction.

FIG. 4 is a schematic perspective view of the spin current-current conversion element according to the first embodiment of the present invention, and shows a microscopic state in which a magnetic field H is applied in a direction orthogonal to a line connecting a pair of Au electrodes 14 ₁ and 14 _2. Irradiate waves.

Figure 5 is a characteristic diagram when the magnetic field is applied in the H direction, FIG. 5 (a) is an explanatory view of a magnetic field strength dependence of the output voltage V, the resonance magnetic field H _FMR is in the vicinity of 136MT, this, A large output voltage was observed in the vicinity of the resonant magnetic field _HFMR . FIG. 5B is an explanatory diagram of the dependency of the output voltage on the microwave power, and the output voltage increases linearly as the microwave power increases. PEDOT: PSS is known to have σ _y / σ _x > 10 ⁵ , and the reason why such an output voltage is obtained even though the spin-orbit interaction is extremely small is very anisotropic. It is considered to be conductive.

  6 is a characteristic diagram when a magnetic field is applied in the −H direction, FIG. 6A is an explanatory diagram of the magnetic field strength dependence of the output voltage V, and FIG. 6B is a microwave of the output voltage. It is explanatory drawing of electric power dependence, and an output voltage increases linearly with the increase in microwave electric power. In this case, a characteristic in which the characteristic of FIG. 4 and the positive / negative of the output voltage are reversed was obtained.

Figure 7 summarizes the results of FIGS. 5 and 6, FIGS. 7 (a) indicates the absorption spectrum of microwave absorption peak is observed in the vicinity of 136MT, and this position is the resonant magnetic field H _FMR Become. FIG. 7B is an explanatory diagram of the magnetic field strength dependence of the output voltage V. Here, measurement of a sample in which a SiO ₂ film is interposed between the Ni ₈₀ Fe ₂₀ film 13 and the PEDOT: PSS film 12 is shown. The results are also shown. In the sample in which the SiO ₂ film is interposed, since the SiO ₂ is an insulating film, the spin current is not injected from the Ni ₈₀ Fe ₂₀ film 13 into the PEDOT: PSS film 12, so the output voltage becomes zero.

FIG. 8 is an explanatory diagram of other characteristics. 8 (a) is an explanatory view of an output voltage when irradiated with microwaves of 100mW from the start of measurement after 15 seconds, the output voltage _{ΔV = V} 100mW _-V 0mW about 5μV is irradiated with microwaves) is obtained It was.

  FIG. 8B is an explanatory diagram of the dependence of the output voltage on the sweep rate. Even if the sweep rate is irradiated with microwaves at three rates of 1 mT / s, 3 mT / s, and 5 mT / s, the change in the output voltage does not occur. I couldn't see it. This result shows that the element temperature rises when microwaves are absorbed, but the fact that the output voltage does not change means that the temperature does not contribute to the output voltage. The sweep plate 1 mT / s represents a magnetic field sweep that changes 1 mT [millitesla] per second.

FIG. 8C is an explanatory diagram of the dependency of the output voltage on the PEDOT: PSS film thickness. It has also been experimentally confirmed that the output voltage decreases when the PEDOT: PSS film thickness exceeds 50 nm. This means that the spin current-current conversion by the spin-orbit interaction occurs near the interface between the Ni ₈₀ Fe ₂₀ film 13 and the PEDOT: PSS film 12.

Thus, in Example 1 of the present invention, since PEDOT: PSS having a large anisotropic conductivity is used as the reverse spin-Hall effect member, the spin-orbit interaction is very small although it is very small. An output voltage E _ISHE was obtained.

Next, with reference to FIG. 9 thru | or FIG. 13, the spin current-current conversion element of Example 2 of this invention is demonstrated. FIGS. 9 and 10 are explanatory diagrams of the manufacturing process of the spin current-current conversion element according to the second embodiment of the present invention. First, as shown in FIG. 9A, GGG (Gd ₃ Ga ₅ O ₁₂ ) A MOD solution having a composition of Y ₃ Fe ₅ O ₁₂ is applied onto the single crystal substrate 21 by a spin coat method. As spin coating conditions in this case, the MOD solution 22 is uniformly applied so that the film thickness after baking is 200 nm by rotating at 5000 rpm for 60 seconds.

  Next, as shown in FIG. 9B, for example, it is dried on a hot plate heated to 50 ° C. for 5 minutes to evaporate excess organic solvent contained in the MOD solution 22, and then in an electric furnace. For example, the oxide layer 23 is formed by temporary baking at 60 ° C. for 60 minutes.

  Next, as shown in FIG. 9C, the oxide layer 23 is crystallized in the main firing in which heating is performed at 725 ° C. for 10 hours in an electric furnace to form the YIG layer 24. Next, as shown in FIG. 10D, the YIG layer 24 is cut out to the size of 2 mm × 2 mm together with the GGG single crystal substrate 21.

Next, as shown in FIG. 10 (e), a liquid obtained by mixing PEDOT and PSS is dropped on the surface of the YIG layer 24, and a PEDOT: PSS film 25 having a thickness of 50 nm is formed by a spin coating method. Finally, as shown in FIG. 10 (f), a pair of Au electrodes 26 ₁ and 26 ₂ are formed on both ends of the PEDOT: PSS coating 25.

FIG. 11 is a schematic perspective view of the spin current-current conversion element according to the second embodiment of the present invention in a state where a magnetic field H is applied in a direction orthogonal to a line connecting a pair of Au electrodes 26 ₁ and 26 ₂ . Irradiate microwaves.

  FIG. 12 is an explanatory diagram of the microwave absorption characteristics and output voltage of the spin current-current conversion element according to Example 2 of the present invention. As shown in FIG. The same microwave absorption characteristics were obtained. Also, as shown in FIG. 12B, when the 6.5 GHz microwave was irradiated, the same output characteristics as in Example 1 were obtained.

FIG. 13 is an explanatory diagram of the microwave frequency dependency of the resonance magnetic field strength _{HFMR and} the microwave frequency dependency of the output voltage of the spin current-current conversion element according to Example 2 of the present invention. As shown in FIG. 13 (a), the resonance magnetic field strength _HFMR increases as the microwave frequency increases. Further, as shown in FIG. 13B, the output voltage slightly decreases as the microwave frequency increases.

  In Example 2 of the present invention, a magnetic dielectric is used as the magnetic material, but as in the case of using a metal magnetic material, the spin-orbit interaction is caused by the large anisotropic conductivity of the inverse spin Hall effect member. The output voltage was so large that it could not be predicted from the strength of the.

Next, a spin current-current conversion element according to Example 3 of the present invention will be described with reference to FIGS. FIG. 14 is a schematic oblique view of a spin current-current conversion element according to Example 3 of the present invention, in which a Ni ₈₀ Fe ₂₀ film 32 is formed on a glass substrate 31, and an inverted spin Hall effect member layer is formed thereon. A PBTT: F4-TCNQ film 33 having a thickness of 50 nm is formed by spin coating using a solution obtained by mixing PBTT and F4-TCNQ.

Then, PBTTT: F4-TCNQ film Au electrodes ₃₄ 1 both ends of the pair of 33, 34 ₂ is formed, in a state of applying a magnetic field H in a direction perpendicular to the line connecting the pair of Au electrodes ₃₄ 1, 34 ₂ Irradiate microwaves.

  FIG. 15 is a molecular structure diagram of PBTTT and F4-TCNQ, FIG. 15A is a molecular structure diagram of PBTTT, and FIG. 15B is a molecular structure diagram of F4-TCNQ. The PBTTT: F4-TCNQ film 33 also has a spin coated in-plane electrical conductivity that is much greater than the electrical conductivity in the film thickness direction.

  FIG. 16 is an explanatory diagram of the output characteristics of the spin current-current conversion element according to Example 3 of the present invention, and in this case as well, output voltage characteristics almost identical to the theoretical calculation results were obtained.

  In Example 3 of the present invention, PBTT and F4-TCNQ were used as the conductive polymer, but the same output voltage characteristics as PEDOT: PSS shown in Example 1 were obtained. This means that the increase in spin current-current conversion efficiency due to the inverse spin Hall effect is not due to a limited specific material, and a similar result can be obtained if the member has anisotropic conductivity. To do.

  Next, with reference to FIG. 17, the spin-current-conversion element of Example 4 of this invention is demonstrated. FIG. 17 is an explanatory diagram of a spin current-current conversion element according to Example 4 of the present invention, and FIG. 17A is a conceptual perspective view of the spin current-current conversion element according to Example 4 of the present invention. FIG. 17B is a perspective view showing the relationship between current and spin current.

As shown in FIG. 17A, a liquid in which PEDOT and PSS are mixed is dropped on an n-type GaAs layer 41 doped with Si of 4.7 × 10 ¹⁸ cm ⁻³ , and the thickness is increased by spin coating. A PEDOT: PSS film 42 having a thickness of 50 nm is formed. Next, the basic structure of the spin current-current conversion element is completed by forming a pair of Au electrodes 43 ₁ and 43 ₂ with details of 2.0 mm × 0.5 mm using a mask vapor deposition method.

When this spin current-current conversion element is irradiated with 10 mW of circularly polarized light 44 having a wavelength λ of λ = 670 nm (hν = 1.85 eV), a spin current is generated in the GaAs layer 41. That is, since excitation is performed with the circularly polarized light 44 having a slightly higher energy than the fundamental absorption edge of GaAs, spin-polarized electrons are excited from the valence band to the conduction band to generate a spin current. In this case, it is necessary to irradiate the circularly polarized light 44 in a direction intersecting the direction connecting the pair of Au electrodes 43 ₁ and 43 ₂ , and typically irradiates in a direction orthogonal to each other.

As shown in FIG. 17B, when the generated spin current J _s flows into the PEDOT: PSS film 42, it is converted into a current by spin-orbit interaction at the interface, and a pair of Au electrodes 43 ₁ , 43 _2. The electromotive force E _ISHE is output during In this, PEDOT: PSS film 42 because conductive inflow direction of the spin current J _s has a higher anisotropic conductive, conversion efficiency is increased.

  The spin current-current conversion element of Example 4 can be expected to be used as a highly sensitive detection element for circularly polarized light, and can also convert circularly polarized components in light in the environment.

Next, with reference to FIG. 18, the spin-current-conversion element of Example 5 of this invention is demonstrated. FIG. 18 is a schematic perspective view of a spin current-current conversion element according to Example 5 of the present invention, in which a YIG layer 52 is formed on a GGG single crystal substrate 51. A PEDOT: PSS film 53 having a thickness of 50 nm is formed thereon by spin-dropping a liquid obtained by mixing PEDOT and PSS. Next, a basic structure of the spin current-current conversion element is completed by forming a pair of Au electrodes 54 ₁ and 54 ₂ with details of 2.0 mm × 0.5 mm using a mask vapor deposition method.

Here, when the heat source 55 is brought into contact with the side where the PEDOT: PSS coating 53 is not provided in a state where the magnetic field H is applied in the longitudinal direction in the drawing, and a temperature difference ▽ T is formed in the longitudinal direction in the drawing, the spin-Seebeck thermally spin current is generated due to the effect, PEDOT by reverse spin Hall: thermoelectromotive force between the pair of Au electrodes ₅₄ 1, 54 ₂ provided at both ends of the PSS coating 53 is obtained.

  Since the spin current-current conversion element of the fifth embodiment functions as a thermoelectric element, power generation using an environmental heat source such as body temperature and waste heat becomes possible.

Next, with reference to FIG. 19, a spin current-current conversion element according to Example 6 of the present invention will be described. FIG. 19 is a schematic perspective view of a spin current-current conversion element according to Example 6 of the present invention. On the piezoelectric effect element 61 including the PZT layer 62 sandwiched between a pair of electrodes 63 ₁ and 63 ₂ , a YIG Layer 64 is provided. A PEDOT: PSS film 65 having a thickness of 50 nm is formed thereon by spin-dropping a liquid obtained by mixing PEDOT and PSS. Next, a pair of Au electrodes 66 ₁ and 66 ₂ are formed with a detail of 2.0 mm × 0.5 mm using a mask vapor deposition method, and a silicone resin layer 67 serving as a heat sink is provided thereon, thereby providing a spin current − The basic structure of the current conversion element is completed.

  Here, when an AC voltage is applied to the piezo effect element 61 with the magnetic field H applied in a direction orthogonal to the longitudinal direction in the drawing, a bulk sound wave is generated and transmitted to the YIG layer 64. An acoustically induced spin current is generated in the YIG layer 64 by transferring energy from a sound wave to a spin wave by magnon-phonon interaction.

The generated spin current flows into the PEDOT: PSS film 53 and an electromotive force is obtained between the pair of Au electrodes 66 ₁ and 66 ₂ provided at both ends of the PEDOT: PSS film 65 by the reverse spin Hall effect.

  Here, in order to clarify the principle, a piezo effect element is provided, but instead of the piezo effect element, a spin current-current conversion element made of a YIG layer / PEDOT: PSS film is brought into contact with a vibration source. Thus, the vibration of the vibration source can be converted into a voltage.

  Next, a spin RAM according to a seventh embodiment of the present invention will be described with reference to FIG. 20. Since the structure of the spin RAM itself is the same as that of the conventional spin RAM, only the memory cell portion is different. The memory cell portion will be described. In this embodiment, the reverse spin Hall effect is not used, but the spin Hall effect that converts a current into a spin current is used.

  FIG. 20 is an explanatory diagram of the spin RAM according to the seventh embodiment of the present invention. FIG. 20 (a) is a schematic perspective view of the vicinity of the magnetoresistive effect element constituting the memory cell, and FIG. It is explanatory drawing of the injection principle of a spin current. As shown in FIG. 20A, a TMR element 72 including a free layer 73, a tunnel insulating film 74 such as MgO or Al—O, a pinned layer 75, and an antiferromagnetic layer 76 is provided on the lower electrode 71. A bit line 77 is provided in contact with the antiferromagnetic layer 76.

On the other hand, a spin injection electrode 78 made of La _2-x Sr _x CuO ₄ which is a layered transition metal oxide is provided so as to be in contact with the free layer 73, and connection wirings 79 ₁ and 79 ₂ are provided for the spin injection electrode 78. . In this case, the spin injection electrode 78 is arranged so that the longitudinal direction thereof is perpendicular to the longitudinal direction of the TMR element 72. Here, by controlling the crystal orientation of La _{2 -x} Sr _x CuO ₄ , which is a layered transition metal oxide, the electric conductivity in the direction perpendicular to the thin film plane is made larger than the electric conductivity in the in-plane direction, and anisotropic It has conductivity.

As shown in FIG. 20B, when a current J _{c is} passed through the spin injection electrode 78, a pure spin current J _s without a charge flow is generated in a direction perpendicular to the current J _c and the free layer 73 is generated. Injected into. At this time, the direction of the spin sigma _s in pure spin current J _s becomes a direction orthogonal to both the current J _c and pure spin current J _s, it acts to convert the magnetization direction M of the free layer 73.

  In Example 7, since the layered transition metal oxide having anisotropic conductivity is used as the spin injection electrode, the spin current injection efficiency can be made larger than the current-spin current conversion efficiency of the material itself. .

DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Spin current-current mutual conversion member layer 3 Spin current generating member layer 4 ₁ , 4 ₂ Electrode 5 ₁ , 5 ₂ Extraction electrode 6 Voltmeter 11 Glass substrate 12 PEDOT: PSS coating 13 Ni ₈₀ Fe ₂₀ film 14 ₁ , 14 ₂ Au electrode 21 GGG single crystal substrate 22 MOD solution 23 Oxide layer 24 YIG layer 25 PEDOT: PSS coating 26 ₁ , 26 ₂ Au electrode 31 Glass substrate 32 Ni ₈₀ Fe ₂₀ film 33 PBTTTT: F4-TCNQ film 34 ₁ , 34 ₂ Au electrode 41 GaAs layer 42 PEDOT: PSS coating 43 ₁ , 43 ₂ Au electrode 44 Circularly polarized light 51 GGG single crystal substrate 52 YIG layer 53 PEDOT: PSS coating 54 ₁ , 54 ₂ Au electrode 55 Heat source 61 Piezo effect Element 62 PZT layer 63 ₁ , 63 ₂ electrode 64 YIG layer 65 PEDOT: PSS Coating 66 ₁ , 66 ₂ Au electrode 67 Silicone resin 71 Lower electrode 72 TMR element 73 Free layer 74 Tunnel insulating film 75 Pinned layer 76 Antiferromagnetic layer 77 Bit line 78 Spin injection electrode 79 ₁ , 79 ₂ Connection wiring

Claims (9)

A spin current generating member layer that generates a pure spin current or a spin wave spin current by supplying energy;
A spin current-current mutual conversion member layer that is bonded to the spin current generation member layer and converts a spin current into a current or converts a current into a spin current;
A pair of electrodes provided on the upstream side and the downstream side in the current flow direction, provided in the spin current-current mutual conversion member layer;
A spintronic device in which the spin current-current mutual conversion member layer has an anisotropic conductivity in which an electric conductivity in an inflow direction of a spin current is higher than an electric conductivity in another direction. The spin current generating member layer is a magnetic layer;
The spintronic device according to claim 1, wherein the spin current-current mutual conversion member layer is an inverse spin Hall effect member layer.   The spintronic device according to claim 2, wherein the supplied energy is any one of heat, microwaves, light, and sound waves.   4. The spintronic device according to claim 3, wherein the reverse spin Hall effect member layer is provided on an insulating substrate, and the magnetic layer is provided on the reverse spin Hall effect member layer.   The spintronic device according to claim 3, wherein the magnetic layer is provided on an insulating substrate, and the reverse spin Hall effect member layer is provided on the magnetic layer. The spin current generating member layer is a semiconductor layer having a zinc blende type crystal structure;
The spin current-current mutual conversion member layer is an inverse spin Hall effect member layer,
The spintronic device according to claim 1, wherein the supplied energy is circularly polarized light. The spin current generating member layer is a magnetic layer;
The spin current-current mutual conversion member layer is a spin Hall effect member layer,
The spintronic device according to claim 1, wherein the supplied energy is an injection current.   The spin current-current interconversion member layer having anisotropic conductivity is formed of a conductive polymer, an organic self-assembled film, an organic charge transfer complex conductor, a metal laminated film, a layered transition metal oxide, or a three-dimensional topological insulation. The spintronic device according to any one of claims 1 to 7, comprising any one of a body. The spintronic device according to claim 8, wherein the conductive polymer is PEDOT: PSS which is a polymer obtained by mixing PEDOT and PSS, or PBTTTT: F4-TCNQ which is a polymer obtained by mixing PBTTTT and F4-TCNQ.