WO2014115518A1 - 熱電変換素子及びその製造方法 - Google Patents
熱電変換素子及びその製造方法 Download PDFInfo
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- WO2014115518A1 WO2014115518A1 PCT/JP2014/000212 JP2014000212W WO2014115518A1 WO 2014115518 A1 WO2014115518 A1 WO 2014115518A1 JP 2014000212 W JP2014000212 W JP 2014000212W WO 2014115518 A1 WO2014115518 A1 WO 2014115518A1
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
- H10N10/10—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/82—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by variation of the magnetic field applied to the device
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/66984—Devices using spin polarized carriers
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
- H10N10/01—Manufacture or treatment
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
- H10N10/80—Constructional details
- H10N10/81—Structural details of the junction
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
- H10N10/80—Constructional details
- H10N10/85—Thermoelectric active materials
- H10N10/851—Thermoelectric active materials comprising inorganic compositions
- H10N10/854—Thermoelectric active materials comprising inorganic compositions comprising only metals
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
- H10N10/80—Constructional details
- H10N10/85—Thermoelectric active materials
- H10N10/851—Thermoelectric active materials comprising inorganic compositions
- H10N10/855—Thermoelectric active materials comprising inorganic compositions comprising compounds containing boron, carbon, oxygen or nitrogen
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
- H10N10/80—Constructional details
- H10N10/85—Thermoelectric active materials
- H10N10/857—Thermoelectric active materials comprising compositions changing continuously or discontinuously inside the material
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N15/00—Thermoelectric devices without a junction of dissimilar materials; Thermomagnetic devices, e.g. using the Nernst-Ettingshausen effect
Definitions
- the present invention relates to a thermoelectric conversion element based on a spin Seebeck effect and an inverse spin Hall effect, and a manufacturing method thereof.
- spintronics In recent years, an electronic technology called “spintronics” has attracted attention. Conventional electronics have used only “charge”, which is one property of electrons, while spintronics also actively uses “spin”, which is another property of electrons. In particular, “spin-current”, which is a flow of spin angular momentum of electrons, is an important concept. Since the energy dissipation of the spin current is small, there is a possibility that highly efficient information transfer can be realized by using the spin current. Therefore, generation, detection and control of spin current are important themes.
- spin-hall effect a phenomenon in which a spin current is generated when a current flows.
- inverse spin-Hall effect an opposite phenomenon that an electromotive force is generated when a spin current flows.
- the spin current can be detected.
- both the spin Hall effect and the reverse spin Hall effect are significantly expressed in a substance (for example, Pt, Pd) having a large “spin orbit coupling”.
- the spin Seebeck effect is a phenomenon in which, when a temperature gradient is applied to a magnetic material, a spin current is induced in a direction parallel to the temperature gradient (see, for example, Patent Document 1 and Patent Document 2). That is, heat is converted into a spin current by the spin Seebeck effect (thermal spin current conversion).
- membrane which is a ferromagnetic metal is reported.
- Non-Patent Documents 1 and 2 report the spin Seebeck effect at the interface between a magnetic insulator such as yttrium iron garnet (YIG, Y 3 Fe 5 O 12 ) and an electromotive film.
- the spin current induced by the temperature gradient can be converted into an electric field (current, voltage) using the above-described inverse spin Hall effect. That is, by using the spin Seebeck effect and the inverse spin Hall effect in combination, “thermoelectric conversion” that converts a temperature gradient into electricity becomes possible. A completely reverse process is also possible in which a current is passed through the same element, the current is converted into a spin current by the spin Hall effect, a heat flow is generated from the spin current by the spin Peltier effect, and a temperature gradient is generated in the element.
- FIG. 1 shows a configuration of a thermoelectric conversion element using the spin Seebeck effect disclosed in Patent Document 1.
- a thermal spin current conversion unit 102 is formed on the sapphire substrate 101.
- the thermal spin current conversion unit 102 has a stacked structure of a Ta film 103, a PdPtMn film 104, and a NiFe film 105.
- the NiFe film 105 is a magnetic film having in-plane magnetization.
- a Pt film 106 is formed as an electromotive film on the NiFe film 105, and both ends of the Pt film 106 are connected to terminals 107-1 and 107-2, respectively.
- the NiFe film 105 plays a role of generating a spin current from the temperature gradient by the spin Seebeck effect, and the Pt film 106 generates an electromotive force from the spin current by the reverse spin Hall effect. It plays a role as a spin current-current conversion material. Specifically, when a temperature gradient is applied in the in-plane direction of the NiFe film 105, a spin current is generated in a direction parallel to the temperature gradient due to the spin Seebeck effect. Then, a spin current flows from the NiFe film 105 to the Pt film 106 or a spin current flows from the Pt film 106 to the NiFe film 105.
- an electromotive force is generated in a direction orthogonal to the spin current direction and the NiFe magnetization direction by the inverse spin Hall effect.
- the electromotive force can be taken out from terminals 107-1 and 107-2 provided at both ends of the Pt film 106.
- FIG. 2 shows a configuration of a vertical thermoelectric conversion element disclosed in Patent Document 2.
- the electromotive layer 120 is stacked on the magnetic layer 110.
- the temperature gradient ⁇ T is applied in the stacking direction.
- the thermal spin current flows in the same direction, that is, from the higher temperature to the lower temperature.
- the thermal spin current further generates a pure spin current in the electromotive film through a process called spin injection at the interface between the magnetic layer 110 and the electromotive layer 120.
- Spin injection is a phenomenon in which spins that precess around the magnetization direction in the vicinity of the interface interact with conduction electrons that do not have spin in the electromotive film, and pass or receive spin angular momentum. .
- a “pure spin current” is generated near the spin injection interface in the electromotive layer 120 due to conduction electrons having spin.
- the up spin and the down spin flow in opposite directions, so there is no charge transfer in the direction of the pure spin current, but only the spin momentum flows.
- a state in which this spin injection phenomenon can occur is expressed as “magnetically coupled”.
- This spin injection phenomenon occurs when the magnetic layer and the electromotive layer are in direct contact, or when the spin angular momentum is close enough to transmit even if they are not in direct contact. Arise. That is, even if there is a gap between the magnetic layer and the electromotive layer or an intermediate layer is inserted, there is magnetic coupling when a spin injection phenomenon can occur. I think.
- the electromotive layer 120 When the electromotive layer 120 is formed of a material having a large spin orbit interaction, an electromotive force is generated in a direction perpendicular to the spin current direction and the magnetization direction by the reverse spin Hall effect.
- the magnitude of the electromotive force obtained depends on the magnitude of the spin current generated in the magnetic layer, the spin current injection efficiency (the spin at the interface with the electromotive layer). Current injection efficiency) and spin current-current conversion efficiency (efficiency in which spin current is converted into electromotive force by the inverse spin Hall effect in the electromotive layer). Accordingly, it is necessary to simultaneously increase the three indices of the magnitude of the spin current itself, the spin current injection efficiency, and the spin current-current conversion efficiency in order to obtain a thermoelectric conversion element with higher output. Among them, improvement of the spin current-current conversion efficiency in the electromotive layer is an important issue in other spintronic devices.
- the material of the electromotive layer has both electric conductivity and spin hole conductivity.
- a dimensionless index representing spin hole conductivity / electric conductivity is called “spin hole angle”.
- the spin Hall angle is used as an index of the magnitude of the spin Hall effect.
- the reverse spin Hall effect is the reverse of the spin Hall effect, and its magnitude also depends on the spin Hall angle.
- Pt having a large spin Hall angle is often used alone as the electromotive layer.
- Au, Ag, Cu, etc. which are similar noble metals, do not reach the spin hole angle of Pt alone, but for example, by introducing a small amount of Fe as an impurity into Au or adding Ir to Cu, Pt In some cases, a spin hole angle larger than that of a simple substance can be obtained.
- the magnitude of the electromotive force obtained in the spin current thermoelectric conversion element depends on the spin current-current conversion efficiency due to the reverse spin Hall effect in the electromotive layer. In order to improve practicality, it is desired to further improve the spin current-current conversion efficiency.
- One object of the present invention is to provide a technique capable of further improving the spin current-current conversion efficiency in a spin current thermoelectric conversion element.
- thermoelectric conversion element in one aspect of the present invention, includes a magnetic layer having in-plane magnetization and an electromotive layer that is magnetically coupled to the magnetic layer.
- the electromotive layer includes a first conductor that exhibits spin-orbit interaction and a second conductor that has lower electrical conductivity than the first conductor.
- thermoelectric conversion element in another aspect of the present invention, includes a step of forming a magnetic layer having in-plane magnetization and a step of forming an electromotive layer that is magnetically coupled to the magnetic layer.
- the step of forming the electromotive layer includes the step of forming a first conductor that exhibits spin-orbit interaction, and the step of forming a second conductor having lower electrical conductivity than the first conductor; ,including.
- thermoelectric conversion element described in patent document 1.
- FIG. It is the schematic which shows a typical vertical thermoelectric conversion element. It is the schematic which shows the thermoelectric conversion element which concerns on embodiment of this invention. It is the schematic which shows the structural example of the electromotive body layer of the thermoelectric conversion element which concerns on embodiment of this invention. It is the schematic for demonstrating the effect
- 3 is a graph showing output characteristics of a thermoelectric conversion element according to Example 1.
- 6 is a graph showing output characteristics of a thermoelectric conversion element according to Example 2.
- 5 is a graph showing output characteristics of a thermoelectric conversion element according to Comparative Example 1.
- 6 is a graph showing output characteristics of thermoelectric conversion elements according to Example 3, Example 4, and Comparative Example 2.
- thermoelectric conversion element and a method for manufacturing the same according to an embodiment of the present invention will be described with reference to the accompanying drawings.
- FIG. 3 schematically shows a thermoelectric conversion element according to the present embodiment.
- the thermoelectric conversion element has a laminated structure of a magnetic layer 10 and an electromotive layer 20.
- the stacking direction of the magnetic layer 10 and the electromotive layer 20 is the z direction.
- the direction orthogonal to the z direction is the in-plane direction.
- the in-plane direction is defined by an x direction and a y direction that are orthogonal to each other.
- the magnetic layer 10 has at least one in-plane magnetization.
- the magnetic layer 10 is formed of a material that exhibits a spin Seebeck effect.
- the material of the magnetic layer 10 may be a ferromagnetic metal or a magnetic insulator.
- the ferromagnetic metal include NiFe, CoFe, and CoFeB.
- magnetic insulators include yttrium iron garnet (YIG, Y 3 Fe 5 O 12 ), YIG doped with bismuth (Bi) (Bi: YIG), and YIG added with lanthanum (La) (LaY 2 Fe 5 O 12 ).
- Spinel ferrite material made of yttrium gallium iron garnet (Y 3 Fe 5 -x Ga x O 12 ), composition MFe 2 O 4 (M is a metal element and includes any one of Ni, Zn, and Co). . From the viewpoint of suppressing heat conduction by electrons, it is desirable to use a magnetic insulator.
- the electromotive layer 20 includes a material that exhibits the reverse spin Hall effect (spin orbit interaction).
- the electromotive layer 20 is formed so as to be magnetically coupled to the magnetic layer 10. Note that in this specification, a state in which a spin injection phenomenon may occur is expressed as “magnetically coupled”. This spin injection phenomenon is close enough that the spin angular momentum can be transmitted when the magnetic layer 10 and the electromotive layer 20 are in direct contact, or even if they are not in direct contact. Occurs in some cases. That is, even if there is a gap between the magnetic layer 10 and the electromotive layer 20 or an intermediate layer is inserted, if the spin injection phenomenon can occur, the magnetic coupling I think there is.
- thermoelectric conversion element When a z-direction temperature gradient is applied to such a thermoelectric conversion element, a spin current is induced at the interface between the magnetic layer 10 and the electromotive layer 20. By converting this spin current into an electric electromotive force by the inverse spin Hall effect in the electromotive layer 20 and taking it out as electric power, “thermoelectric conversion that generates a thermoelectromotive force from a temperature gradient” becomes possible.
- Electromotive layer hereinafter, the electromotive layer 20 of the thermoelectric conversion element according to the present embodiment will be described in detail. As will become apparent later, according to the present embodiment, the electromotive layer 20 having excellent spin current-current conversion efficiency is realized.
- FIG. 4 is a schematic diagram illustrating a configuration example of the electromotive layer 20 according to the present embodiment.
- the electromotive layer 20 includes a conductor layer 21 and a weak conductor layer 22. More specifically, both the conductor layer 21 and the weak conductor layer 22 have a layered structure parallel to the xy plane, and the conductor layers 21 and the weak conductor layers 22 are alternately stacked in the z direction. ing. That is, the electromotive layer 20 has a multilayer structure of the conductor layer 21 and the weak conductor layer 22.
- the conductor layer 21 (first conductor) is formed of a material that exhibits an inverse spin Hall effect (spin orbit interaction).
- the conductor layer 21 contains a metal material having a large spin orbit interaction.
- a metal material for example, Au, Pt, Pd having a relatively large spin orbit interaction, a transition metal having a d or f orbit, or an alloy material containing them is conceivable.
- the same effect can be obtained by simply doping a general metal film material such as Cu with a material such as Fe or Ir at about 0.5 to 10 mol%.
- the material of the conductor layer 21 may be an oxide such as ITO (Indium Tin Oxide) or a semiconductor.
- the weak conductor layer 22 (second conductor) has a lower electrical conductivity than the conductor layer 21 described above.
- the electrical conductivity that characterizes the weak conductor layer 22 is a direction parallel to the spin current injected into the electromotive layer 20 when a temperature gradient in the z direction is applied to the thermoelectric conversion element (many The case relates to the electrical conductivity in the z direction). This is relatively small compared to the electric conductivity in the current generation direction (in-plane direction) in the conductor layer 21.
- the electrical conductivity here is related to the effect of shape, the effect of the surface and interface, the external field such as the electric field and the magnetic field, the temperature, the phase transition of the material, etc. in the state where the electromotive layer 20 is produced. It means the electrical conductivity actually expressed including effects.
- thermoelectric conversion element includes a magnetic layer 10 having in-plane magnetization M (x direction), and an electromotive layer 20 disposed on the magnetic layer 10.
- the electromotive layer 20 has a multilayer structure of a conductor layer 21 and a weak conductor layer 22.
- a temperature gradient ⁇ T from the magnetic layer 10 to the electromotive layer 20 is applied to the thermoelectric conversion element having such a structure.
- a thermal spin current is generated in the magnetic layer 10 through the interaction between the spins.
- spin injection occurs in such a manner that spin angular momentum is transferred to the conduction electrons of the electromotive layer 20, and a pure spin current is generated in the electromotive layer 20.
- This pure spin current is generated so that an up spin parallel to the magnetization M of the magnetic layer 10 and an antiparallel down spin coexist. Then, the upspin flows along the temperature gradient, and the downspin flows up the temperature gradient.
- the scattering probability of the spin conduction electrons increases.
- the motion of the spin conduction electrons changes to a direction perpendicular to both the magnetization M and the temperature gradient, that is, a lateral motion.
- a current flows in a direction orthogonal to the pure spin current, that is, an inverse spin Hall effect is exhibited. This can be said to be an “exogenous effect” as opposed to an intrinsic effect resulting from the crystal structure, the structure of the electron orbit, and the like.
- the spin Hall conductivity generated at this time is a very large value reflecting the large intra-layer electrical conductivity of the conductor layer 21.
- the electroconductivity in the z direction of the electromotive layer 20 when defining the spin hole angle is small because it reflects the electroconductivity due to the weak conductor layer 22 and scattering between layers. As a result, a large spin hole angle can be obtained.
- the extrinsic spin Hall effect can be obtained by providing the electroconductive layer 20 with the weak conductor layer 22. Furthermore, by combining a new mechanism of anisotropy of electrical conductivity, a large spin Hall angle can be realized by a mechanism that has never existed before. As a result, the conversion efficiency of the spin current-current conversion material is improved, and the conversion efficiency of the spin current thermoelectric conversion element is also greatly improved.
- the configuration of the electromotive layer 20 according to the present embodiment is not limited to that shown in FIG. If generalized, if the electromotive layer 20 is provided with the 1st conductor which expresses a spin orbit interaction, and the 2nd conductor whose electrical conductivity is lower than the 1st conductor, Good. Thereby, the above effect can be obtained to some extent.
- the second conductor is formed so as to extend substantially parallel to the interface (that is, the xy plane) between the magnetic layer 10 and the electromotive layer 20.
- the interface that is, the xy plane
- the first conductor and the second conductor may have a layer structure parallel to the xy plane.
- the electromotive layer 20 preferably has a laminated structure of the conductor layer 21 (first conductor) and the weak conductor layer 22 (second conductor). At this time, a multilayer structure in which at least one of the conductor layer 21 and the weak conductor layer 22 is formed in two or more layers is more preferable.
- the film thickness of each layer of the laminated structure can be optimized so that the device performance is maximized.
- a thickness corresponding to a monoatomic layer is also possible.
- the wave function of the elements introduced to form the layer spreads and it is possible to form a non-discontinuous two-dimensional potential. Can be regarded as a film.
- an optimum value can be determined in consideration of the spin current diffusion length, electrical conductivity, etc. in the electromotive layer 20 so that the thermoelectric conversion output is maximized.
- the conductor layer 21 is in direct contact with the magnetic layer 10, but the weak conductor layer 22 may be in direct contact with the magnetic layer 20. Good.
- the conductor layer 21 and the weak conductor layer 22 may be further multilayered, a material having a non-uniform composition may be introduced inside, or the conductor Only the layer 21 and the weak conductor layer 22 may be partially continuously stacked, or the output may be improved by various devices.
- the electromotive layer 20 according to the present embodiment can be applied not only to a vertical thermoelectric conversion element but also to a horizontal thermoelectric conversion element as shown in FIG. The same effect can be obtained even with a horizontal thermoelectric conversion element.
- thermoelectric conversion element 3. Manufacturing Method Next, a manufacturing method of the thermoelectric conversion element according to the present embodiment will be described.
- the magnetic layer 10 As a method for forming the magnetic layer 10, sputtering method, organometallic decomposition method (MOD method), sol-gel method, aerosol deposition method (AD method), ferrite plating method, liquid phase epitaxy method, solid phase epitaxy method, gas phase Examples include an epitaxy method, a dip method, a spray method, a spin coating method, and a printing method.
- the magnetic layer 10 is formed on a support.
- a magnetic insulator fiber formed using a crystal pulling method or the like, or a bulk body formed using a sintering method, a melting method, or the like can be used as the magnetic layer 10.
- the conductor layer 21 and the weak conductor layer 22 are formed by any of the sputtering method, vapor deposition method, plating method, screen printing method, ink jet method, spray method, and spin coating method. A method is mentioned. Further, coating / sintering of a nanocolloid solution (reference: JP-A-7-188934 and JP-A-9-20980) can be used.
- thermoelectric conversion element by the present inventor will be described.
- a crystalline gadolinium gallium garnet (GGG) wafer having a thickness of 700 ⁇ m was used as a substrate (not shown), and a spin current thermoelectric conversion element was fabricated thereon.
- GGG gadolinium gallium garnet
- Bi: YIG bismuth-substituted yttrium iron garnet
- the Bi: YIG film was formed by an organometallic decomposition method (MOD method).
- MOD method organometallic decomposition method
- a MOD solution manufactured by Kojundo Chemical Laboratory Co., Ltd. was used as the solution.
- a crystalline Bi: YIG film having a film thickness of about 65 nm was formed on the GGG substrate.
- the electromotive layer 20 was formed. Specifically, a 5 nm Pt film was deposited by sputtering as the conductor layer 21 in contact with the magnetic layer 10. Subsequently, a weak conductor layer 22 was formed on the conductor layer 21. Further, a 5 nm Pt film was deposited by sputtering as the conductor layer 21 on the weak conductor layer 22.
- Example 1 As the weak conductor layer 22, a 1 nm thick Ti thin film was deposited by sputtering.
- Example 2 As the weak conductor layer 22, a 1 nm-thick W thin film was deposited by sputtering.
- Comparative Example 1 As Comparative Example 1, a sample having no weak conductor layer 22 was prepared. In this case, the electromotive layer 20 is composed of only a 10 nm Pt thin film.
- Example 1 For each of Example 1, Example 2, and Comparative Example 1, a 2 ⁇ 8 mm strip-shaped evaluation element was cut out and the thermoelectric conversion performance was measured. Specifically, spin Seebeck signals were measured when various temperature differences were applied in the z direction to each evaluation element. 7A to 7C show the measurement results for Example 1, Example 2, and Comparative Example 1, respectively. In order to confirm whether or not the signal is a spin Seebeck signal, an external magnetic field is applied, and a state in which the output voltage V ISHE is reversed according to the reversal of the magnetization direction is measured.
- the spin Seebeck constant S was estimated from the observed value of the output voltage VISHE and the temperature difference applied to the entire sample. As is clear from FIGS. 7A to 7C, both Example 1 and Example 2 have a large spin Seebeck constant S compared to Comparative Example 1. Since the value of the internal resistance R is almost the same in Example 1, Example 2 and Comparative Example 1, it can be said that both Examples 1 and 2 have obtained a large conversion efficiency exceeding Comparative Example 1.
- Example 3 As the conductor layer 21, a 5 nm Cu film was deposited by sputtering instead of the above Pt film. Further, as the weak conductor layer 22, a 1 nm thick Pt thin film was deposited by sputtering.
- Example 4 As the conductor layer 21, a 5 nm Cu film was deposited by sputtering instead of the above Pt film. Further, as the weak conductor layer 22, a W thin film having a thickness of 1 nm was deposited by sputtering.
- Comparative example 2 As Comparative Example 2, a sample having no weak conductor layer 22 was prepared. In this case, the electromotive layer 20 is composed only of a 10 nm Cu thin film.
- thermoelectric conversion performance was measured in the same manner as described above.
- FIG. 8 shows the measurement results for each of Example 3, Example 4, and Comparative Example 2.
- Example 3 as a result of selecting Pt having a smaller electric conductivity than Cu and a large spin Hall angle as a weak conductor, a spin Seebeck constant S about 10 times larger than that of Comparative Example 2 could be obtained.
- Example 4 the electric conductivity is smaller than that of Cu, and the spin hole angle is selected from Wt having a sign opposite to that of Pt or Cu as a weak conductor.
- the Seebeck constant S could be obtained.
- the spin current-current conversion function of the entire electromotive layer 20 can be controlled by combining the magnitudes of the spin hole angles and materials having different signs.
- thermoelectric conversion element comprising a body and a second conductor having lower electrical conductivity than the first conductor.
- thermoelectric conversion element of Additional remark 1
- the said 2nd conductor is a thermoelectric element formed so that it might extend in substantially parallel to the interface of the said magnetic body layer and the said electromotive body layer. Conversion element.
- thermoelectric conversion element (Appendix 3) The thermoelectric conversion element according to appendix 1 or 2, wherein the first conductor and the second conductor have a laminated structure.
- thermoelectric conversion element (Appendix 4) The thermoelectric conversion element according to appendix 3, wherein at least one of the first conductor and the second conductor is formed in two or more layers.
- thermoelectric conversion element comprising: forming a first conductor that exhibits spin-orbit interaction; and forming a second conductor having lower electrical conductivity than the first conductor.
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Abstract
Description
図3は、本実施の形態に係る熱電変換素子を概略的に示している。熱電変換素子は、磁性体層10と起電体層20の積層構造を有している。ここで、磁性体層10と起電体層20の積層方向は、z方向である。また、z方向に直交する方向は、面内方向である。面内方向は、互いに直交するx方向とy方向とで規定される。
以下、本実施の形態に係る熱電変換素子の起電体層20について詳しく説明する。後に明らかになるように、本実施の形態によれば、優れたスピン流-電流変換効率を有する起電体層20が実現される。
図4は、本実施の形態に係る起電体層20の構成例を示す概略図である。図4に示される例において、起電体層20は、伝導体層21と弱伝導体層22を備えている。より詳細には、伝導体層21と弱伝導体層22は共にxy平面に平行な層状構造を有しており、それら伝導体層21と弱導電体層22とがz方向に交互に積層されている。つまり、起電体層20は、伝導体層21と弱伝導体層22の多層構造を有している。
次に、図5を参照して、本実施の形態に係る熱電変換素子における、熱スピン流-起電力変換を説明する。図5において、熱電変換素子は、面内磁化M(x方向)を有する磁性体層10と、その磁性体層10上に配置された起電体層20を備えている。起電体層20は、伝導体層21と弱伝導体層22の多層構造を有している。
本実施の形態に係る起電体層20の構成は、図4で示されたものに限られない。一般化すれば、起電体層20は、スピン軌道相互作用を発現する第1の伝導体と、その第1の伝導体よりも電気伝導性が低い第2の伝導体とを備えていればよい。これにより、上記の効果はある程度得られる。
次に、本実施の形態に係る熱電変換素子の製造方法を説明する。
図6を参照して、本願発明者による熱電変換素子の作成例を説明する。本例では、厚さ700μmの結晶性ガドリニウムガリウムガーネット(GGG)ウェハを基板(図示されない)として用い、その上にスピン流熱電変換素子を作製した。
上記の弱伝導体層22として、厚さ1nmのTi薄膜をスパッタリングにより蒸着した。
上記の弱伝導体層22として、厚さ1nmのW薄膜をスパッタリングにより蒸着した。
比較例1として、弱伝導体層22を有さないサンプルを作成した。この場合、起電体層20が、10nmのPt薄膜だけで構成される。
伝導体層21として、上記のPt膜の代わりに、5nmのCu膜をスパッタリングにより蒸着した。また、弱伝導体層22として、厚さ1nmのPt薄膜をスパッタリングにより蒸着した。
伝導体層21として、上記のPt膜の代わりに、5nmのCu膜をスパッタリングにより蒸着した。また、弱伝導体層22として、厚さ1nmのW薄膜をスパッタリングにより蒸着した。
比較例2として、弱伝導体層22を有さないサンプルを作成した。この場合、起電体層20が、10nmのCu薄膜だけで構成される。
20 起電体層
21 伝導体層
22 弱伝導体層
Claims (5)
- 面内磁化を有する磁性体層と、
前記磁性体層と磁気的に結合する起電体層と
を備え、
前記起電体層は、
スピン軌道相互作用を発現する第1の伝導体と、
前記第1の伝導体よりも電気伝導性が低い第2の伝導体と
を備える
熱電変換素子。 - 請求項1に記載の熱電変換素子であって、
前記第2の伝導体は、前記磁性体層と前記起電体層との界面に略平行に延在するように形成された
熱電変換素子。 - 請求項1又は2に記載の熱電変換素子であって、
前記第1の伝導体と前記第2の伝導体は、積層構造を有している
熱電変換素子。 - 請求項3に記載の熱電変換素子であって、
前記第1の伝導体と前記第2の伝導体の少なくともいずれかが2層以上形成されている
熱電変換素子。 - 面内磁化を有する磁性体層を形成し、
前記磁性体層と磁気的に結合する起電体層を形成し、
前記起電体層を形成する際に、
スピン軌道相互作用を発現する第1の伝導体を形成し、
前記第1の伝導体よりも電気伝導性が低い第2の伝導体を形成する
熱電変換素子の製造方法。
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JP2016080394A (ja) * | 2014-10-10 | 2016-05-16 | 日本電気株式会社 | スピン熱流センサ及びその製造方法 |
GB2544801A (en) * | 2015-11-27 | 2017-05-31 | Univ Loughborough | A thermoelectric conversion device and method of power harvesting |
JP2017199743A (ja) * | 2016-04-26 | 2017-11-02 | 日本電信電話株式会社 | スピン軌道相互作用の制御方法 |
CN108055872A (zh) * | 2015-09-09 | 2018-05-18 | 英特尔公司 | 具有自旋霍尔电极和电荷互连的自旋逻辑 |
JP2019068086A (ja) * | 2017-02-27 | 2019-04-25 | Tdk株式会社 | スピン流磁化回転素子、磁気抵抗効果素子及び磁気メモリ |
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JP2014183176A (ja) * | 2013-03-19 | 2014-09-29 | Nec Corp | スピン流熱電変換素子 |
JP2016080394A (ja) * | 2014-10-10 | 2016-05-16 | 日本電気株式会社 | スピン熱流センサ及びその製造方法 |
CN108055872A (zh) * | 2015-09-09 | 2018-05-18 | 英特尔公司 | 具有自旋霍尔电极和电荷互连的自旋逻辑 |
CN108055872B (zh) * | 2015-09-09 | 2022-05-13 | 英特尔公司 | 具有自旋霍尔电极和电荷互连的自旋逻辑 |
GB2544801A (en) * | 2015-11-27 | 2017-05-31 | Univ Loughborough | A thermoelectric conversion device and method of power harvesting |
JP2017199743A (ja) * | 2016-04-26 | 2017-11-02 | 日本電信電話株式会社 | スピン軌道相互作用の制御方法 |
JP2019068086A (ja) * | 2017-02-27 | 2019-04-25 | Tdk株式会社 | スピン流磁化回転素子、磁気抵抗効果素子及び磁気メモリ |
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