JP5585314B2 - Thermoelectric conversion element and thermoelectric conversion device - Google Patents

Description

  The present invention relates to a thermoelectric conversion element and a thermoelectric conversion device, and more particularly to a thermoelectric conversion element and a thermoelectric conversion device that are characterized by a configuration that increases the degree of design freedom of the element.

  In recent years, the need for clean energy has been screamed as a countermeasure against global warming, and the application of the thermoelectric effect is expected as such a clean energy source. As an example, it has been proposed to convert waste heat and exhaust heat of a thermal power plant, factory, or automobile into electric power using a Seebeck effect element (see, for example, Patent Document 1).

  However, the efficiency of the current Seebeck effect element is not sufficient, and it is necessary to further increase the thermoelectric conversion efficiency for practical use as a clean energy source.

The performance index Z, which is an index of the thermoelectric conversion efficiency of the Seebeck effect element using different types of metal junctions of two kinds of metals with different Seebeck coefficients, is S, the Seebeck coefficient is S, the electrical conductivity is σ, and the thermal conductivity is κ. Then,
Z = S ² × (σ / κ) (1)
It is expressed. The direction of generation of the electromotive force V is parallel to the temperature gradient ▽ T.

  In this case, the Seebeck coefficient S, the electrical conductivity σ, and the thermal conductivity κ are all material-specific values. Therefore, the performance index Z is also a material-specific value. In order to realize highly efficient thermoelectric generation, the performance index Z A high thermoelectric conversion element is required. In order to increase the figure of merit Z, it was necessary to develop a new substance.

  On the other hand, as an alternative to the degree of freedom of electron charge used in the field of electronics such as current semiconductor devices, spintronics utilizing the degree of freedom of spin other than the charge of the electron, that is, the degree of freedom of spin angular momentum, is available. It attracts attention as a leader of next-generation electronics 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 spin current generation method, a spin current by spin pumping has been proposed (see, for example, Non-Patent Document 1), and the present inventors have also used the inverse spin Hall effect (ISHE) as a spin current detection method. Has been proposed (see, for example, Non-Patent Document 2).

Figure 12 is an explanatory view of an inverted spin Hall, when injecting the pure spin current J _s in the sample, a current flows J _c by inverse spin Hall effect in the direction perpendicular to the direction of the pure spin current J _s. By utilizing the inverse spin Hall, the potential difference V is generated in an end portion of the sample, by detecting the potential difference V, it allows detection of the presence or absence of flow of the pure spin current J _s.

  However, in the thermoelectric conversion using the Seebeck effect described above, as can be seen from the equation (1), when a substance having a high electric conductivity σ is used, the figure of merit Z is increased. However, in the case of a metal, since a material having a high electrical conductivity σ has a high thermal conductivity κ, the effect of improving the figure of merit Z by improving the electrical conductivity σ is offset by the thermal conductivity κ. .

  Therefore, the present inventor has proposed a spin-Seebeck effect element using a junction between a magnetic material such as NiFe and a metal such as Pt having a large spin-orbit interaction (see, for example, Patent Document 2). In this spin-Seebeck effect element, a thermal spin current generated by a temperature gradient in a magnetic material such as NiFe is subjected to spin exchange at the interface with Pt, and the pure spin current generated by the exchange causes a direction perpendicular to the direction of the pure spin current. The flowing current is output as a voltage at both ends of the magnetic body.

  This is because, in the case of a magnetic material, particularly a ferromagnetic material, if a temperature gradient is applied with an external magnetic field applied, there is a difference between an up-spin current and a down-spin current, and a thermal spin current is generated. This is the result of using the results found.

The figure of merit Z in this case is S _s , the electrical conductivity of the spin-Seebeck effect element, σ _I the electrical conductivity of the reverse spin Hall member, and κ _F the thermal conductivity of the magnetic material.
Z = S _s ² × (σ _I / κ _F ) (2)
It is expressed. In this case, the figure of merit differs from the conventional figure of merit in that the electrical conductivity of the numerator and the thermal conductivity of the denominator are different materials, so the figure of merit can be changed significantly by selecting the material of the device. .

However, in this case, the direction of generation of the electromotive force V is perpendicular to the temperature gradient ▽ T because the reverse spin Hall effect is used. Since the thermoelectric conversion ability S _s of the spin-Seebeck effect element is proportional to the length in the direction perpendicular to the temperature gradient ▽ T, the figure of merit Z can be modulated by the sample size as compared with the conventional Seebeck effect element. There are features. That is, by configuring the sample size such that the length in the direction perpendicular to the temperature gradient 長 T is increased, an electromotive force V proportional to the length can be obtained.

  Since spin current is not a physical conserved quantity, by utilizing such thermal spin current conversion, spin current can be extracted continuously only by applying a temperature gradient, and therefore the thermoelectromotive force is also continuous. Can be taken out.

  However, in this spin-Seebeck effect element, a metal having a high thermal conductivity κ is used for the thermal spin current generating member. Therefore, if the sample size is increased in order to increase the electromotive force V, a uniform temperature gradient ▽ It becomes difficult to provide T. Therefore, at present, it is difficult to realize an industrially usable thermoelectric conversion element using an all-metal spin-Seebeck effect element.

  Therefore, the present inventor has proposed a spin-Seebeck effect element using a magnetic dielectric material having a low thermal conductivity such as YIG instead of metal as a thermal spin current generating member (see, for example, Patent Document 3). . Here, a spin-Seebeck effect element using a magnetic dielectric will be described with reference to FIG.

FIG. 13 is a schematic perspective view of a spin-Seebeck effect element using a magnetic dielectric. Striped nonmagnetic conductors 52 and 53 are provided on the magnetic dielectric layer 51. In this state, an external magnetic field H is applied in the direction of the arrow, and a uniform temperature gradient ▽ T is provided, so that the magnetic dielectric / nonmagnetic conductor interface positioned on the high temperature side and the low temperature side of the element has an opposite sign. The pure spin current _Js flows. The pure spin current J _S injected into the normal conductors 52 and 53 is converted into a current in a direction perpendicular to the temperature gradient ▽ T by the electron relativity effect, and is supplied to the nonmagnetic conductor 52 provided on the high temperature side and the low temperature side. Thermoelectromotive _{forces VISHE} that are opposite to each other are generated in the provided nonmagnetic conductor 53. That is, the electromotive force due to the inverse spin-Hall effect is generated in the outer product direction of the injected pure spin current _JS and the spin polarization direction (magnetization direction M of the magnetic dielectric).

The magnetic dielectric 51 may be anything as long as it contains Fe or Co. However, practically, YIG (yttrium iron garnet) or yttrium gallium iron garnet, which is easily available and has low dissipation of spin angular momentum, In terms of general formula, Y ₃ Fe _5-x Ga _x O ₁₂ (where x <5) is used. Further, as the nonmagnetic conductors 52 and 53 serving as the inverse spin Hall effect member, it is desirable to use any of Pt, Au, Pd, Ag, Bi, or an element having an f orbit. Since these elements have a large spin-orbit interaction, the thermal spin wave spin current and the pure spin current can be exchanged with high efficiency at the interface with the magnetic dielectric 51.

  FIG. 14 is an explanatory diagram of the spin wave spin current. As schematically shown in FIG. 14, the spin wave spin current is a phenomenon in which the spin precesses around the equilibrium position and the change in phase is expressed as a wave. It is transmitted through the spin system, and the thermal spin wave spin current is a phase change caused by heat. The spin wave spin current is characterized by being able to propagate over a long distance of several millimeters or several centimeters while the spin diffusion length of a conduction electron type pure spin current is several nanometers to several hundred nanometers. This has already been confirmed by various experiments (see, for example, Non-Patent Document 3).

In this thermal spin wave spin current-pure spin current exchange, the thermal spin wave spin current generated by the temperature gradient in the magnetic dielectric is exchanged with the spin in the metal electrode, and a pure spin current is generated in the metal electrode, A current is generated by the pure spin current, and a thermoelectromotive force _VISHE is generated at both ends of the metal electrode by the current.

JP 2007-165463 A JP 2009-130070 A International publication pamphlet WO 2009/151000

Phys. Rev. B19, p. 4382, 1979 Applied Physics Letters Vol. 88, p. 182509, 2006 Nature, Vol. 464, p.262-266, 2010

  However, in the case of the spin-Seebeck effect element using the above-described magnetic dielectric, the temperature gradient ▽ T is provided in the in-plane direction of the magnetic dielectric layer, so that the contact state with the heat source is limited, such as a boiler or a chimney As a result, there is a problem that the actual application range is narrow.

Therefore, an object of the present invention is to increase the degree of design freedom when extracting power from a temperature gradient.

  In order to solve the above problems, the present invention provides a thermoelectric conversion element, wherein a thermal spin wave spin current generating member made of a magnetic dielectric is provided with an inverse spin Hall effect member, and the thickness of the thermal spin wave spin current generating member is In addition, a magnetic field is applied in the direction perpendicular to the longitudinal direction of the inverse spin Hall effect member and in the direction perpendicular to the temperature gradient by the magnetic field applying means, and a thermal spin wave is generated in the reverse spin Hall effect member. The spin current is converted into voltage and extracted.

  Thus, by providing the temperature gradient in the thickness direction of the thermal spin wave spin current generating member, the thermoelectromotive force can be generated in the direction perpendicular to the temperature gradient, and the element design flexibility is increased.

  The magnetic dielectric may be a ferrimagnetic dielectric, a ferromagnetic dielectric, or an antiferromagnetic dielectric. When the magnetic dielectric is a ferrimagnetic dielectric or a ferromagnetic dielectric, an antiferromagnetic layer that contacts the magnetic dielectric and fixes the magnetization direction may be provided as a magnetic field applying means.

The magnetic dielectric may be anything as long as it contains Fe or Co, but garnet ferrite, spinel ferrite such as Mn _x Zn _1-x Fe ₂ O ₄ (where 0 <x <1), or It is desirable to use hexagonal ferrite.

Further, as the reverse spin Hall effect member, any one of Pt, Au, Pd, Ag, Bi, a transition metal element having f or 3d orbital, or an element having any of these alloys, or these It is desirable to use a material of the above and an alloy of Cu, Al, or Si.

  A plurality of the above-described thermoelectric conversion elements are alternately arranged so that the magnetization directions are opposite to each other, or are arranged so that the magnetization directions are the same, and the reverse spin is performed so that the thermoelectromotive force is connected in series. A thermoelectric conversion device that outputs high electromotive force can be configured by connecting ends of the Hall effect members to each other.

  Alternatively, a reverse spin Hall effect member is provided on both sides of a thermal spin wave spin current generating member made of a magnetic dielectric material to constitute a thermoelectric conversion element, and a plurality of the thermoelectric conversion elements are stacked via a nonmagnetic insulator, The ends of the reverse spin Hall effect members are connected to each other so that the thermoelectromotive force is connected in series, a temperature gradient is provided in the stacking direction of the thermoelectric conversion elements, and the length of the reverse spin Hall effect member is increased by a magnetic field applying means. A magnetic field may be applied in a direction orthogonal to the direction and in a direction orthogonal to the temperature gradient, and the thermal spin wave spin current may be converted into a voltage and extracted by the inverse spin Hall effect member.

  In the present invention, since the temperature gradient is provided in the thickness direction of the thermal spin wave spin current generating member, the thermoelectromotive force can be generated in the direction perpendicular to the temperature gradient, which increases the degree of freedom in device design. As a result, the applicable heat source increases dramatically.

It is a notional block diagram of the thermoelectric conversion element of embodiment of this invention. It is the modification which deform | transformed in order to make contrast with the structure of a prior art example easy. It is structure explanatory drawing when the Pt electrode side is made into the high temperature side. It is structure explanatory drawing when the Pt electrode side is made into the low temperature side. It is explanatory drawing of a measurement result. It is a notional block diagram of the thermoelectric conversion apparatus of Example 2 of this invention. It is a notional block diagram of the thermoelectric conversion apparatus of Example 3 of this invention. It is a notional block diagram of the thermoelectric conversion apparatus of Example 4 of this invention. It is a notional block diagram of the thermoelectric conversion apparatus of Example 5 of this invention. It is composition explanatory drawing of the thermoelectric conversion apparatus of Example 6 of this invention. It is explanatory drawing of the measurement result in Example 6 of this invention. It is explanatory drawing of a reverse spin Hall effect. It is a schematic perspective view of a spin-Seebeck effect element using a magnetic dielectric. It is explanatory drawing of a spin wave spin current.

Here, with reference to FIG.1 and FIG.2, embodiment of this invention is described. FIG. 1 is a conceptual configuration diagram of a thermoelectric conversion element according to an embodiment of the present invention, FIG. 1 (a) is a conceptual perspective view, and FIG. 1 (b) is a reverse spin Hall effect member side. FIG. 1C is a conceptual cross-sectional view when the temperature is raised, and FIG. 1C is a conceptual cross-sectional view when the temperature of the reverse spin Hall effect member is lowered. In addition, the arrow in a figure has shown the direction of the heat flow.

  As shown in the figure, an inverse spin Hall effect member 12 is provided on a thermal spin wave spin current generating member 11 made of a magnetic dielectric, and a temperature gradient (longitudinal direction in the figure) is formed in the thickness direction of the thermal spin wave spin current generating member 11. And applying a magnetic field H in a direction orthogonal to the longitudinal direction of the reverse spin Hall effect member 12 by the magnetic field applying means to take out the thermoelectromotive force V from both ends of the reverse spin Hall effect member 12.

FIG. 2 is a modified view in which the structure of the present invention is modified to facilitate comparison with the structure of the conventional example shown in FIG. The reverse spin Hall effect members 12 ₁ and 12 ₂ made of a conductor are provided, a temperature gradient ▽ T is provided in the longitudinal direction of the thermal spin wave spin current generation member 11, and the thickness direction of the thermal spin wave spin current generation member 11 is increased. An external magnetic field H is applied.

In this case, thermal spin-wave spin current _{J s} is the interface between the inverse spin Hall effect member ₁₂ 1, 12 _2, by the exchange of thermal spin-wave spin current and pure spin current, reverse spin Hall effect member ₁₂ 1, 12 ₂ Is injected as a pure spin current.

The injected pure spin current causes a current to flow in a direction orthogonal to the temperature gradient due to the electron relativistic effect, and a thermoelectromotive force V _ISHE is generated in the longitudinal direction of the inverse spin Hall effect members 12 ₁ , 12 ₂ . At this time, _since the direction of the thermoelectromotive force V _ISHE at the interface between both the reverse spin Hall effect members 12 ₁ and 12 ₂ is the same as the direction of the flowing spin current, the thermoelectromotive force V _ISHE becomes the same direction.

The thermal spin wave spin current generating member 11 of the element shown in FIG. 2 is extremely shortened in the temperature gradient direction to have the same length as the thickness, and one of the reverse spin Hall effect members 12 ₁ and 12 ₂ is removed. If it is rotated by 90 °, it becomes equivalent to the thermoelectric conversion element shown in FIG. Removal of the inverse spin Hall effect member 12 _2, becomes equivalent to FIG. 1 (b), the Removal of the inverse spin Hall effect member 12 _1, is equivalent to FIG. 1 (c).

The magnetic dielectric, but may be any as far as including Fe or Co, garnet _{ferrite, Mn x Zn 1-x Fe} 2 O 4 ( where, 0 <x <1) spinel ferrite or the like, hexagonal Ferrite, particularly YIG (yttrium iron garnet) and yttrium gallium iron garnet, which are easily available and have low spin angular momentum dissipation, that is, Y ₃ Fe _{5 -x} Ga _x O _{12 when} expressed in a general formula. (However, it is desirable to use garnet ferrite having 0 ≦ x <5) or garnet ferrite in which Y sites of YIG are replaced with atoms such as La, for example, LaY ₂ Fe ₅ O ₁₂ . This is because Y ₃ Fe _5−x Ga _x O ₁₂ has a large charge gap and therefore has very few conduction electrons, and therefore, the dissipation of spin angular momentum by the conduction electrons is small. However, an inexpensive material such as ordinary ferrite Fe ₃ O ₄ is desirable from the viewpoint of cost.

  Further, when an antiferromagnetic dielectric is used, typically nickel oxide and FeO can be mentioned, but most of the magnetic dielectric is an antiferromagnetic dielectric. When the magnetic dielectric layer is made of a ferromagnetic dielectric, it is desirable to provide an antiferromagnetic layer in order to fix the magnetization direction of the magnetic dielectric layer.

  When a conductive magnetic material is used instead of the magnetic dielectric material, a structure in which an inverse spin Hall effect member and a conductive magnetic material that does not generate thermoelectromotive force are joined is electrically connected. Therefore, it is very difficult to extract the thermoelectromotive force from the inverse spin Hall effect member.

  Further, as a growth method of the magnetic dielectric layer, sputtering method, MOD method (Metal-organic decomposition method), sol-gel method, liquid phase epitaxy method, floating zone method, aerosol deposition method, Any of the position methods (see the above-mentioned Patent Document 4 if necessary) may be used. Further, the crystallinity of the magnetic dielectric layer 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 spin-coated on a GGG (Gd ₃ Ga ₅ O ₁₂ ) single crystal substrate having a {100} plane as a main surface. Apply with. 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, it is dried on a hot plate heated to 150 ° C. for 5 minutes to evaporate excess organic solvent contained in the MOD solution. Next, in an electric furnace, for example, the oxide layer is formed by pre-baking by heating at 550 ° C. for 5 minutes.

  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, after the YIG layer is cut out to a predetermined size, a thermoelectric conversion element is obtained by providing an inverse spin Hall effect member such as a Pt electrode on the YIG layer using a mask sputtering method.

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, as the reverse spin Hall effect member, any one of Pt, Au, Pd, Ag, Bi, a transition metal element having f or 3d orbital, or an element having any of these alloys, or these It is desirable to use a material of the above and an alloy of Cu, Al, or Si. Since the former element has a large spin orbit interaction, it is possible to exchange heat spin wave spin current and pure spin current with high efficiency at the interface with the magnetic dielectric. However, from the viewpoint of cost, the former material and an alloy of Cu, Al, or Si are desirable.

  Here, with reference to FIG. 3 thru | or FIG. 5, the thermoelectric conversion apparatus of Example 1 of this invention is demonstrated. FIG. 3 is an explanatory diagram of the configuration when the Pt electrode side that is the reverse spin Hall effect member is the high temperature side, FIG. 3 (a) is a schematic front view, and FIG. 3 (b) is a schematic side view. FIG. 3C is a top view of the main part in the vicinity of the thermoelectric conversion element.

  A thermoelectric conversion element 20 composed of a single crystal YIG plate 21 and a Pt electrode 22 is fixed on the Cu block 41, and heat is transferred between the Cu block 42 contacting the heat source by a U-shaped heat propagation member 43 made of brass. Connect. Therefore, the temperature gradient ▽ T is upward. Here, the external magnetic field H is applied in the direction perpendicular to the longitudinal direction of the Pt electrode and in the direction perpendicular to the temperature gradient ＴT (leftward in the figure).

  The size of the YIG plate 21 is 1 mm thick × 2 mm wide × 6 mm long, and the size of the Pt electrode 22 is 15 nm thick, 0.5 mm wide, and 6 mm long. At this time, the temperature difference ΔT is measured by the thermocouple 44, and the thermoelectromotive force generated in the longitudinal direction of the Pt electrode 22 is measured by the voltmeter 45.

  FIG. 4 is an explanatory diagram of the configuration when the Pt electrode side, which is an inverse spin Hall effect member, is a low temperature side, FIG. 4 (a) is a schematic front view, and FIG. 4 (b) is a schematic side view. FIG. 4C is a top view of the main part in the vicinity of the thermoelectric conversion element.

  A thermoelectric conversion element 20 composed of a single crystal YIG plate 21 and a Pt electrode 22 is fixed on a Cu block 42 that is in contact with a heat source, and heat is transferred between the Cu block 41 and a U-shaped heat propagation member 43 made of brass. Connect. Therefore, the temperature gradient ▽ T is downward. Here, as in the case of FIG. 3, the external magnetic field H is applied in the direction perpendicular to the longitudinal direction of the Pt electrode and in the direction perpendicular to the temperature gradient ▽ T (leftward in the figure), and the temperature difference ΔT is measured by the thermocouple 44. At the same time, the thermoelectromotive force generated in the longitudinal direction of the Pt electrode 22 is measured by the voltmeter 45.

  FIG. 5 is an explanatory diagram of measurement results, FIG. 5 (a) is a measurement result of the configuration of FIG. 3, and FIG. 5 (b) is a measurement result of the configuration of FIG. As shown in FIG. 5, in each case, an electromotive force of about 15 μV was obtained at a temperature difference ΔT = 20 ° C. under the condition of H = 1000 [Oe]. When the external magnetic field H is applied in the longitudinal direction of the Pt electrode 22, that is, when θ = 0 °, the electromotive force is generated in the width direction of the Pt electrode 22. Can not be taken out.

  Next, with reference to FIG. 6, the thermoelectric conversion apparatus of Example 2 of this invention is demonstrated. 6 is a conceptual configuration diagram of a thermoelectric conversion device according to a second embodiment of the present invention, FIG. 6 (a) is a conceptual plan view, and FIG. 6 (b) is an AA ′ diagram in FIG. 6 (a). It is a conceptual sectional view along an alternate long and short dash line connecting. An IrMn antiferromagnetic plate 23 having a magnetization direction is attached to the back surface of the YIG plate 21 of the thermoelectric conversion element 20 including the YIG plate 21 and the Pt electrode 22 described above. At this time, the magnetization direction is given so that the magnetization direction M of the IrMn antiferromagnetic plate 23 is orthogonal to the longitudinal direction of the Pt electrode 22.

  The thermoelectric conversion elements 20 are alternately arranged and fixed on the flexible sheet 24 such as a PET sheet so that the magnetization directions M are opposite to each other, and the Pt electrodes 22 of the adjacent thermoelectric conversion elements 20 are connected to the adjacent thermoelectric elements. The Pt electrode 22 and the Cu connection conductor 25 of the conversion element 20 are sequentially connected.

The thermoelectromotive force can be taken out by bringing the flexible sheet 24 into close contact with the heat source and cooling the Pt electrode 22 side by air cooling or water cooling. The thermoelectromotive force V _tot at this time is expressed as follows, where n is the number of thermoelectric conversion elements 20 and V is the thermoelectromotive force of one thermoelectric conversion element 20.
V _tot = n × V
It becomes.

  Next, with reference to FIG. 7, the thermoelectric conversion apparatus of Example 3 of this invention is demonstrated. FIG. 7 is a conceptual configuration diagram of a thermoelectric conversion device according to a second embodiment of the present invention, FIG. 7 (a) is a conceptual plan view, and FIG. 7 (b) is an AA ′ in FIG. 7 (a). It is a conceptual sectional view along an alternate long and short dash line connecting.

  An IrMn antiferromagnetic layer 32 is deposited in a line-and-space manner on a heat-resistant flexible sheet 31 such as a heat-resistant glass fiber sheet by using a mask sputtering method. At this time, an external magnetic field is applied, and the IrMn antiferromagnetic material layer 32 is magnetized in the direction of the external magnetic field.

Next, the magnetic dielectric layer 33 is formed by selectively depositing Fe ₃ O ₄ on the IrMn antiferromagnetic layer 32 by using an aerosol deposition method. Next, the Pt electrode 34 is formed on the magnetic dielectric layer 33 by using a mask vapor deposition method to obtain the thermoelectric conversion element 30.

Next, one end of the Pt electrode 34 of each adjacent thermoelectric conversion element 30 is sequentially connected to the opposite end of the Pt electrode 34 of the adjacent thermoelectric conversion element 30 using the Cu connection conductor 35. The thermoelectromotive force can be taken out by bringing the heat-resistant flexible sheet 31 into close contact with the heat source and cooling the Pt electrode 34 side by air cooling or water cooling. The thermoelectromotive force V _tot at this time is also assumed that the number of thermoelectric conversion elements 30 is n and the thermoelectromotive force of one thermoelectric conversion element 30 is V.
V _tot = n × V
It becomes. In this case, since the magnetic dielectric layer 33 in each thermoelectric conversion element 30 is magnetized in a uniform direction, the magnetic dielectric layer 33 can be magnetized by an external magnetic field without using the IrMn antiferromagnetic layer 32. good.

Next, with reference to FIG. 8, the thermoelectric conversion apparatus of Example 4 of this invention is demonstrated. FIG. 8 is a conceptual configuration diagram of a thermoelectric conversion device according to a fourth embodiment of the present invention, FIG. 8A is a conceptual side view, and FIG. 8B is AA ′ in FIG. It is a conceptual sectional view along an alternate long and short dash line connecting. Pt electrodes 22 ₁ and 22 ₂ are mask-deposited on a pair of opposing main surfaces of the YIG plate 21 to form the thermoelectric conversion element 26.

The thermoelectric conversion element 26 are laminated with a nonmagnetic insulator 27 such as a SiO ₂ or an insulating resin, one end of the Pt electrode 22 ₁ and the Pt electrode 22 ₂ of the other end located on the The thermoelectric conversion device is manufactured by sequentially connecting with the Cu connection conductor 28.

When a temperature gradient ▽ T is provided in the stacking direction of this thermoelectric converter, and an external magnetic field H is applied so as to be orthogonal to the longitudinal direction of the Pt electrodes 22 ₁ and 22 ₂ and the temperature gradient ▽ T, one YIG plate 21 Pure spin current _Js is injected into the two Pt electrodes 22 ₁ , 22 ₂ from the interfaces with the Pt electrodes 22 ₁ , 22 ₂ on both sides in the direction indicated by the arrows in the figure, and the reverse spin in the Pt electrodes 22 ₁ , 22 ₂ It is converted into electromotive force by the Hall effect.

Therefore, since the thermoelectromotive force generated per thermoelectric conversion element is twice the thermoelectromotive force of the thermoelectric conversion element of FIG. 1, the thermoelectromotive force V _tot is n, where n is the number of thermoelectric conversion elements 26.
V _tot = n × (2 × V)
It becomes.

Next, with reference to FIG. 9, the thermoelectric conversion apparatus of Example 5 of this invention is demonstrated. FIG. 9 is a conceptual configuration diagram of a thermoelectric conversion apparatus according to Embodiment 5 of the present invention. A laminate in which the YIG plate 21 is sandwiched between a Pt electrode 22 and a paramagnetic conductor 29 having a small spin orbit interaction such as Cu is laminated via a nonmagnetic insulator 27 such as SiO ₂ or an insulating resin. The thermoelectric conversion device is manufactured by sequentially connecting the end of the paramagnetic conductor 29 to the end of the paramagnetic conductor 29 by the Cu connecting conductor 28.

When a temperature gradient ▽ T is provided in the stacking direction of the thermoelectric converter, and an external magnetic field H is applied so as to be orthogonal to the longitudinal direction of the Pt electrode 22 and the temperature gradient ▽ T, one YIG plate 21 and Pt electrode 22 A pure spin current J _s is injected from the interface in the direction indicated by the arrow in the figure, and converted into an electromotive force by the reverse spin Hall effect in the Pt electrodes 22 ₁ and 22 ₂ . Since the paramagnetic conductor 29 is made of a material having a small spin orbit interaction, no thermoelectromotive force is generated in the paramagnetic conductor 29 due to the reverse spin Hall effect.

Therefore, since the thermoelectromotive force generated per thermoelectric conversion element is the same as the thermoelectromotive force of the thermoelectric conversion element in FIG. 1, the thermoelectromotive force V _tot is expressed as follows:
V _tot = n × V
It becomes. In this case, although the thermoelectromotive force is halved compared with the above-mentioned Example 4, the electrical interconnection of the laminate is facilitated.

  Next, with reference to FIG.10 and FIG.11, the thermoelectric conversion apparatus of Example 6 of this invention is demonstrated. FIG. 10 is a configuration explanatory view of a thermoelectric conversion device according to a sixth embodiment of the present invention, FIG. 10 (a) is a schematic front view, FIG. 10 (b) is a schematic side view, and FIG. c) is a top view of the main part in the vicinity of the thermoelectric conversion element. Here, the case where the Pt electrode side that is the reverse spin Hall effect member is set to the low temperature side as in FIG. 4 is described, but the Pt electrode side that is the reverse spin Hall effect member is set to the high temperature side as in FIG. It is also good.

A thermoelectric conversion element 60 composed of a Mn _0.75 Zn _0.25 Fe ₂ O ₄ plate 61 composed of a sintered body and a Pt electrode 62 is fixed on the Cu block 42 that is in contact with the heat source. It is thermally connected through an Al ₂ O ₃ plate 63 by a U-shaped heat propagation member 43 made of brass. Therefore, the temperature gradient ▽ T is downward.

  Here, as in the case of FIG. 4, the external magnetic field H is applied in the direction perpendicular to the longitudinal direction of the Pt electrode 62 and in the direction perpendicular to the temperature gradient ▽ T (leftward in the figure), and the temperature difference ΔT is applied by the thermocouple 44. While measuring, the thermoelectromotive force generated in the longitudinal direction of the Pt electrode 62 is measured by the voltmeter 45.

The size of the Mn _0.75 Zn _0.25 Fe ₂ O ₄ plate 61 is 1 mm thick × 2 mm wide × 6 mm long, and the size of the Pt electrode 62 is 15 nm thick × 0.5 mm wide × long. The length is 6 mm. The size of the Al ₂ O ₃ plate 63 is 0.5 mm thick × 5 mm wide × 5 mm long, and is interposed in order to electrically insulate the thermoelectric conversion element 60 from the heat propagation member 43 during electromotive force measurement. As long as the insulator has a high thermal conductivity, it may not be Al ₂ O ₃ .

  FIG. 11 is an explanatory diagram of the measurement results, and FIG. 11A is a correlation diagram of the thermoelectromotive force V and the temperature difference ΔT. Here, the temperature difference ΔT = under the condition of H = 1000 [Oe]. An electromotive force of about 2 μV was obtained at 15 ° C. When the external magnetic field H is applied in the longitudinal direction of the Pt electrode 62, that is, when θ = 0 °, the electromotive force is generated in the width direction of the Pt electrode 22. Can not be taken out.

  FIG. 11B is an explanatory diagram of the temperature difference dependence of the thermoelectromotive force when the external magnetic field is swept, and the lower line is a characteristic curve when the external magnetic field is swept from minus to plus. The side line is a characteristic curve when the external magnetic field is changed from plus to minus.

As is clear from the figure, since a clear hysteresis loop appears at any temperature difference ΔT, the observed electromotive force is derived from the magnetization reversal of the Mn _0.75 Zn _0.25 Fe ₂ O ₄ plate 61. It can be seen that the inversion, that is, the symmetry of the inverse spin Hall effect is matched.

The Mn _0.75 Zn _0.25 Fe ₂ O ₄ plate of Example 6 has a smaller thermoelectromotive force than YIG, but this is because magnon is scattered at the sintered body, that is, the microcrystalline interface. In addition, it is considered that the magnetic loss (relaxation constant α) is much larger than YIG. In Example 6, (MnZn) Fe ₂ O ₄ having a composition ratio of Mn: Zn = 3: 1 is used, but the composition ratio is arbitrary.

11 Thermal spin wave spin current generating member 12, 12 ₁ , 12 ₂ Reverse spin Hall effect member 20, 60 Thermoelectric conversion element 21 YIG plate 22, 22 ₁ , 22 ₂ , 62 Pt electrode 23 IrMn antiferromagnetic material plate 24 Flexible Sheet 25, 28 Cu connection conductor 26 thermoelectric conversion element 27 nonmagnetic insulator 29 paramagnetic conductor 30 thermoelectric conversion element 31 heat resistant flexible sheet 32 IrMn antiferromagnetic layer 33 magnetic dielectric layer 34 Pt electrode 35 Cu connection Conductor 41, 42 Cu block 43 Heat propagation member 44 Thermocouple 45 Voltmeter 51 Magnetic dielectric layer 52, 53 Nonmagnetic conductor 61 Mn _0.75 Zn _0.25 Fe ₂ O ₄ plate 63 Al ₂ O ₃ plate

Claims (10)

  A reverse spin Hall effect member is provided in a thermal spin wave spin current generating member made of a magnetic dielectric, a temperature gradient is provided in the thickness direction of the thermal spin wave spin current generation member, and the reverse spin Hall effect member is provided by a magnetic field applying means. A thermoelectric conversion element in which a magnetic field is applied in a direction perpendicular to the longitudinal direction of the material and in a direction perpendicular to the temperature gradient, and the thermal spin wave spin current is converted into a voltage and extracted by the inverse spin Hall effect member.   The thermoelectric conversion element according to claim 1, wherein the magnetic dielectric is one of a ferrimagnetic dielectric, a ferromagnetic dielectric, and an antiferromagnetic dielectric.   The magnetic dielectric is made of a ferrimagnetic dielectric or a ferromagnetic dielectric, and the magnetic field applying means is an antiferromagnetic layer that is in contact with the magnetic dielectric and fixes its magnetization direction. Thermoelectric conversion element.   The thermoelectric conversion element according to any one of claims 1 to 3, wherein the magnetic dielectric is made of garnet ferrite, spinel ferrite, or hexagonal ferrite. The thermoelectric conversion element according to claim 4, wherein the magnetic dielectric is garnet ferrite made of Y ₃ Fe _{5 -x} Ga _x O ₁₂ (where 0 ≦ x <5). The thermoelectric conversion element according to claim 4, wherein the magnetic dielectric is spinel ferrite made of Mn _x Zn _1-x Fe ₂ O ₄ (where 0 <x <1). The reverse spin Hall effect member is a transition metal element having Pt, Au, Pd, Ag, Bi, f orbit, or 3d orbit, or an alloy thereof, or each material and Cu, Al, or Si. The thermoelectric conversion element according to any one of claims 1 to 6, wherein the thermoelectric conversion element is made of any one of the alloys.   A plurality of thermoelectric conversion elements according to any one of claims 1 to 7 are alternately arranged so that the magnetization directions are opposite to each other, and the reverse spin is performed so that the thermoelectromotive force is connected in series. A thermoelectric conversion device in which end portions of Hall effect members are connected to each other.   A plurality of the thermoelectric conversion elements according to any one of claims 1 to 7 are arranged so that the magnetization directions are the same as each other, and the reverse spin hole so that the thermoelectromotive force is connected in series. The thermoelectric conversion apparatus which connected the edge part of the effect member mutually. A reverse spin Hall effect member is provided on both sides or one side of a thermal spin wave spin current generating member made of a magnetic dielectric material to constitute a thermoelectric conversion element, and a plurality of the thermoelectric conversion elements are laminated via a nonmagnetic insulator, The ends of the reverse spin Hall effect members are connected to each other so that the thermoelectromotive force is connected in series, a temperature gradient is provided in the stacking direction of the thermoelectric conversion elements, and the length of the reverse spin Hall effect member is increased by a magnetic field applying means. A thermoelectric conversion device that applies a magnetic field in a direction orthogonal to a direction and in a direction orthogonal to the temperature gradient, and converts a thermal spin wave spin current into a voltage at the inverse spin Hall effect member to extract the voltage.

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