JP2017084854A - Thermoelectric conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoelectric conversion device capable of generating a voltage by temperature difference, while suppressing leakage magnetic field more significantly than before.SOLUTION: A thermoelectric conversion device 1 includes a thermoelectric conversion element 2 composed of an antiferromagnetic material having a non-collinear spin structure. When giving a temperature difference by feeding heat flux for the thermoelectric conversion element in a direction orthogonal to the in-plane micro-magnetization direction Ar2, a voltage can be generated by abnormal Nernst effect, in a direction orthogonal to the micro-magnetization direction Ar2 and heat flux direction Ar1, respectively. Since the thermoelectric conversion element 2 is formed of an antiferromagnetic material not having strong magnetization like an antiferromagnetic material, the thermoelectric conversion device 1 can inhibit generation of a leakage magnetic field more significantly than a conventional thermoelectric conversion device using a ferromagnetic material.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a thermoelectric conversion device.

  In recent years, a thermoelectric conversion device utilizing an abnormal Nernst effect has been considered (for example, see Patent Document 1). Here, the abnormal Nernst effect is a phenomenon in which, when a heat flow is passed through a magnetized magnetic body, a voltage is generated in a direction (outer product direction) orthogonal to the magnetization direction and the heat flow direction of the magnetic body. For this reason, in a conventional thermoelectric conversion device, a ferromagnetic material having strong magnetization in a predetermined direction as a magnetic material is used as a thermoelectric conversion element, and a temperature difference is given in a direction orthogonal to the magnetization direction of the ferromagnetic material of the thermoelectric conversion element. And getting voltage.

JP 2014-72256 A

  However, since the conventional thermoelectric conversion device uses a thermoelectric conversion element made of a ferromagnetic material, there is a problem that a large leakage magnetic field is generated by the ferromagnetic material. Thus, when the leakage magnetic field from the thermoelectric conversion element is large, a plurality of thermoelectric conversion elements cannot be densely provided in the thermoelectric conversion device, and peripheral devices around the thermoelectric conversion device are also affected by the leakage magnetic field. Since there is a possibility of some influence, the leakage magnetic field hinders high integration. Therefore, in such a thermoelectric conversion device, it is desired to develop a new thermoelectric conversion device having a new structure in which the leakage magnetic field can be significantly suppressed as compared with the conventional one.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a thermoelectric conversion device that can generate a voltage due to a temperature difference and can significantly suppress a leakage magnetic field as compared with the related art.

  The thermoelectric conversion device of the present invention includes a thermoelectric conversion element made of an antiferromagnetic material having a non-collinear spin structure, and the thermoelectric conversion element has a direction perpendicular to the in-plane micromagnetization direction due to anomalous Nernst effect. A voltage is generated due to a temperature difference between the two.

  According to the present invention, even a thermoelectric conversion element made of an antiferromagnetic material can generate a voltage due to a temperature difference due to the anomalous Nernst effect. By forming the thermoelectric conversion element with a magnetic material, the leakage magnetic field can be significantly suppressed as compared with a conventional thermoelectric conversion device using a ferromagnetic material.

It is explanatory drawing which shows typically the state which the abnormal Nernst effect expresses in a non-collinearity antiferromagnetic material. Mn 3 is a diagram illustrating the direction of spin of localization of _Sn. It is a state diagram which shows the range which can be set as the thermoelectric conversion element among the compounds of Mn and Ni. It is the schematic which shows the structure of a thermoelectric conversion device. The voltage _{S xy} per unit temperature in the Mn ₃ Sn, is a graph showing the relationship between the external magnetic field B. And conventional ferromagnetic, for the _Mn 3 Sn, the voltage _{S xy} per unit temperature, and the magnetization _{M s,} is a table summarizing the proportionality factor _{Q s.} It is the schematic which shows the structure of the thermoelectric conversion device by other embodiment.

(1) Antiferromagnetic material used for thermoelectric conversion element First, an antiferromagnetic material serving as a thermoelectric conversion element of a thermoelectric conversion device according to the present invention will be described. The antiferromagnet used as the thermoelectric conversion element is a non-collinear antiferromagnet (hereinafter also referred to as a noncollinear antiferromagnet), and the magnetic moment of atoms on the lattice points (local It has a spin structure in which the directions of the existing spins are not parallel to each other. Non-collinear antiferromagnets include coplanar structures in which the magnetic moments in the spin structure are inclined in the same plane, and non-coplanar structures in which the direction of the magnetic moment is not in the same plane but is three-dimensionally inclined. There is a thing of sex.

  In both non-coplanar and non-coplanar antiferromagnets, the leakage magnetic field is suppressed due to the fact that the magnetic moments are tilted with respect to each other. When a heat flow is applied, a phenomenon (abnormal Nernst effect) in which a voltage is generated in a direction (outer product direction) orthogonal to the micromagnetization direction and the heat flow direction of the antiferromagnet can be exhibited.

  For example, as shown in FIG. 1, in a non-coplanar antiferromagnetic material, each magnetic moment M1 of an atom A on a lattice point has a spin structure in which the atoms are three-dimensionally inclined, and the electrons responsible for conduction When (ie, the conduction electron D) passes through each site of the spin structure, the direction of the spin Da of the conduction electron D is directed to the direction of the magnetic moment M1 due to the influence of the magnetic moment M1. Since the magnetic moments M1 are inclined in different directions and are not parallel to each other, as shown on the right side in the figure, when the conduction electron D makes a round of the nearest lattice point, the spin Da of the conduction electron D is obtained. The direction of is rotating. The rotational motion of the spin Da of the conduction electron D induces the rotational motion of the orbital motion of the conduction electron D. The rotational motion of the orbital motion of the conduction electrons D induced in this way forms an electric field in a direction perpendicular to the heat flow direction when coupled with the heat flow when a temperature difference is caused by flowing the heat flow, and anomalous Nernst effect Is expressed. A non-collinear antiferromagnet with coplanarity also exhibits an anomalous Nernst effect on the same principle.

  The magnetization direction caused by such an abnormal Nernst effect is determined by the rotational direction of the orbital motion of the spin Da. Incidentally, the non-collinear antiferromagnetic material can reverse the direction of the magnetic moment M1 by, for example, a spin transfer torque (spin injection) method, a magnetic field application method, or the like. Due to the inversion, the rotation direction of the orbital motion of the spin Da changes.

Here, as the non-collinear antiferromagnetic material, for example, there is Mn ₃ Sn, and as an example thereof, description will be given focusing on Mn ₃ Sn. Mn ₃ Sn is a hexagonal crystal, and between 50 [K] to 430 [K], as shown in FIG. 2, the a axis ([2-1-10]) and the b axis ([-12-10] ]) And the ab surface has a structure in which a kagome lattice having a strain in the distance between adjacent Mn (manganese) is formed and the kagome lattice is laminated. The magnetic moment (direction of localized spin) M2 of Mn exists in the ab plane in a zero magnetic field, and geometric frustration appears as an inverted triangular spin structure. Further, Mn ₃ Sn constitutes a chiral spin structure having a vector chirality opposite to that of a normal 120 ° spin structure.

In Mn ₃ Sn, among the magnetic moments M2 of three adjacent Mn, one magnetic moment M2 is parallel to the easy axis, but the other two magnetic moments M2 are inclined from the easy axis. The magnetic moments M2 are inclined with respect to each other. In this way, in Mn ₃ Sn which is a non-collinear antiferromagnetic material, the localized magnetic moments M2 are inclined to each other, and a small ferromagnetic moment is induced. The thermoelectric conversion device according to the present invention is used in a state where the magnetic moment M2 of Mn in Mn ₃ Sn serving as the thermoelectric conversion element is oriented in a predetermined direction.

Mn ₃ Sn serving as a thermoelectric conversion element has a magnetic moment M2 of Mn of 2.78 × 10 ⁻²³ [A · m ² ] (3 [μ _B ]) or less. The magnetic moments M2 of the three Mn atoms having the chiral spin structure cancel each other, but the magnetic moments are not completely canceled. That is, the thermoelectric conversion element made of Mn ₃ Sn has 2.78 × 10 ⁻²⁶ [JT ^{−1 /} Mn] (0.003 [μm] due to two magnetic moments M2 inclined to the local easy axis in the chiral spin structure. _B / Mn]) or less weak magnetic moment remains, resulting in a state of being magnetized in a predetermined minute magnetization direction. Thus, although the thermoelectric conversion element formed by Mn ₃ Sn becomes weakly magnetized, it is due to a very weak magnetic moment, and therefore, the leakage magnetic field is remarkably suppressed as compared with the ferromagnetic material. obtain.

Incidentally, this Mn ₃ Sn reverses this magnetic moment M2 of Mn in the first magnetization state as shown in FIG. 2 by, for example, a spin transfer torque (spin injection) method or a magnetic field application method. The magnetization state may be a second magnetization state in which the magnetic moment M2 is changed in a different direction. Similarly to the first magnetization state, Mn ₃ Sn in the second magnetization state, the magnetic moments M2 of the three Mn of the chiral spin structure cancel each other incompletely, leaving a weak magnetic moment, and its direction (magnetization direction) However, the direction of the minute magnetization is opposite to that of the first magnetization state.

Incidentally, this Mn ₃ Sn can return the reversed magnetic moment M2 in the second magnetization state to the first magnetization state again by, for example, the spin transfer torque (spin injection) method or the magnetic field application method. Thus, Mn ₃ Sn can repeatedly change the magnetic moment M2 between the first magnetization state and the second magnetization state.

Note that Mn ₃ Sn forming the thermoelectric conversion element may be Mn _{(3 + x)} Sn _(1-x) (0 ≦ x ≦ 0.2).

In this embodiment, Mn ₃ Sn has been described as the non-collinear antiferromagnetic material forming the thermoelectric conversion element. However, the present invention is not limited to this, and non-colinear other than Mn ₃ Sn is used. A linear hexagonal antiferromagnetic material may be applied. Such non-collinear hexagonal antiferromagnetic materials include, for example, Mn ₃ Ge, Mn ₃ Ga and the like, and even such antiferromagnetic materials are similar to the above-described Mn ₃ Sn. An effect can be obtained. The Further, an antiferromagnetic material that is non-coplanar and has a magnetic moment of a chiral spin structure may be used as the thermoelectric conversion element. Examples of such antiferromagnetic materials include cubic substances and compounds.

The cubic antiferromagnetic material may be, for example, a cubic alloy containing Mn of γ phase (FCC (face-centered cubic) structure) or a cubic alloy containing Fe. Specifically, γ- (Fe, Mn), Mn ₃ Ir, and Mn ₃ Pt can be applied as the thermoelectric conversion element. Further, as indicated by hatching in the state diagram of FIG. 3, a thermoelectric conversion element may be formed by using Ni in a cubic crystal that contains a certain ratio or more, exhibits antiferromagnetism, and is Mn and Ni. Some compounds of Mn and Ni that are tetragonal can also be used.

When Mn ₃ Sn is used as the antiferromagnetic material forming the thermoelectric conversion element, a voltage larger than that of a general ferromagnetic material such as FePt or MnGa can be obtained at room temperature or lower. Is confirmed.

(2) Configuration of Thermoelectric Conversion Device Next, a thermoelectric conversion device using the above-described antiferromagnetic material will be described. As shown in FIG. 4, the thermoelectric conversion device 1 according to the present invention includes a thermoelectric conversion element 2 made of a non-collinear antiferromagnetic material described in “(1) Antiferromagnetic material used for thermoelectric conversion element”. And the voltage device 3 is connected to the opposing end faces 2a and 2b of the thermoelectric conversion element 2 via wiring. Here, the thermoelectric conversion element 2 is formed in, for example, a rectangular parallelepiped shape. In this case, end faces 2a and 2b to which wirings are connected are arranged to face each other along the arrow y direction, and an arrow z orthogonal to the arrow y direction. The back surface 2c and the front surface 2d may be disposed to face each other along the direction, and the heat flow surfaces 2e and 2f may be disposed to face each other along the arrow x direction orthogonal to the arrow y and z directions.

In the thermoelectric conversion element 2, the arrow z direction from the back surface 2c to the front surface 2d is orthogonal to the arrow x and y directions and becomes the minute magnetization direction Ar2, and minute magnetization M _s is generated in the plane toward the minute magnetization direction Ar2. It is configured to be able to. In this case, in the thermoelectric conversion element 2, the heat flow Q flows from one heat flow surface 2 e to the other heat flow surface 2 f in the direction of the arrow x orthogonal to the directions of the arrows y and z, so that the in-plane minute magnetization direction Ar 2. A temperature difference occurs between the heat flow surfaces 2e and 2f in the direction of the arrow x orthogonal to the direction of the arrow. As a result, the thermoelectric conversion element 2 has end faces 2a and 2b facing in the direction of the arrow y (outer product direction) perpendicular to the heat flow direction Ar1 in which the temperature difference is caused by the abnormal Nernst effect and the in-plane minute magnetization direction Ar2, respectively. A voltage is generated between them.

  At this time, the thermoelectric conversion device 1 according to the present invention has a conventional thermoelectric conversion using a ferromagnetic material because the thermoelectric conversion element 2 is formed of an antiferromagnetic material having no strong magnetization such as a ferromagnetic material. The generation of the leakage magnetic field can be significantly suppressed as compared with the device.

(3) Verification Test Next, a rectangular parallelepiped thermoelectric conversion element 2 was prepared from Mn ₃ Sn, and the voltage value due to the abnormal Nernst effect at 200 [K] and 300 [K] was examined. Here, a sample of Mn ₃ Sn was produced as follows. First, a plurality of polycrystalline samples were prepared by arc melting a mixture of Mn and Sn in a clean argon atmosphere. Mn was added in excess (10 mol%) exceeding the normal composition amount in consideration of loss during arc melting and crystal growth. The obtained polycrystalline material was used for crystal growth by the Bridgman method. X-ray diffraction measurement of the obtained single crystals and powders suggested a hexagonal Mn ₃ Sn single phase with lattice constants a = 5.66 (1) Å and c = 4.53 (1) Å.

Moreover, in the analysis by a scanning electron microscope and an energy dispersive X-ray analyzer (SEM-EDX, Scanning Electron Microscope-Energy Dispersive X-ray Detector), it was confirmed that Mn ₃ Sn is a bulk phase. According to inductively coupled plasma (ICP) spectroscopy, the composition of the plurality of single crystals was Mn _3.02 Sn _0.98 . That is, Mn per crystal lattice was 3.02 and Sn was 0.98, and Mn was excessive. In order to measure resistivity and magnetization, a plurality of grown single crystals were arranged using a Laue diffractometer, and a rectangular parallelepiped sample was prepared.

Next, this sample was used as the thermoelectric conversion element 2 of Example 1, the thermoelectric conversion element 2 was set in the chamber, and the inside of the chamber was set to 200 [K] or 300 [K]. Next, in a chamber of 200 [K] or 300 [K], a heat flow at a predetermined temperature (6 [K] or 9 [K]) is caused to flow toward one heat flow surface 2 e of the thermoelectric conversion element 2, A temperature difference was given to the opposing heat flow surfaces 2e and 2f of the conversion element 2. Here, flowing parallel to the heat flow and [01-10] of _Mn 3 Sn, further _Mn 3 Sn a-axis of the ([2-1-10]) and parallel to the external magnetic field (B [Oe]) was applied. Note that “−” written in the Miller index means a bar attached to the index immediately after that. Then, when the relationship between the voltage per unit temperature (S _xy [μV / K]) of Mn ₃ Sn and the external magnetic field (B [Oe]) was examined, the result shown in FIG. 5 was obtained.

From the result of FIG. 5, Mn ₃ Sn at 200 [K] has a voltage S _xy per unit temperature of about 1.5 [μV / K] with respect to changes in the applied external magnetic field ( +0.75 [μV / K] to −0.75 [μV / K]). Further, Mn ₃ Sn at 300 [K] has a voltage S _xy per unit temperature of about 0.92 [μV / K] (+0.46 [+ [ Hysteresis varying from [mu] V / K] to -0.46 [[mu] V / K]) was obtained. From this result, it was confirmed that Mn ₃ Sn exhibits an abnormal Nernst effect and generates a voltage at a normal use environment temperature such as room temperature even when the external magnetic field is zero.

Further, when the in-plane magnetization M _s of Mn ₃ Sn at 300 K was measured with a magnetic property measuring apparatus, it was a very small 0.72 [emu / cc] as shown in FIG. 6 (in FIG. 6). , “M _s (emu / cc)”). Further, the proportionality factor Q _s of Mn ₃ Sn was 510 [μV / TK]. Here, 200 and the voltage _{S xy} per unit temperature when the [K], the voltage _{S xy} per unit temperature when the 300 [K], and the magnetization _{M s,} for a proportional factor _{Q s, Mn} 3 Sn The numerical values of Example 1 and ferromagnetic materials (Comparative Examples 1 to 5) are summarized in FIG.

Note that FePt (Comparative Example 1), FePd (Comparative Example 2), MnGa (Comparative Example 3), Mn ₂ Ga (Comparative Example 4), and Co / Each numerical value of Ni (Comparative Example 5) is a numerical value based on “Hasegawa et al., Appl. Phys. Lett. 106, 252405 (2015)”. From the results of FIG. 6, it can be seen that at 300 [K], the magnetization M _s in the Mn ₃ Sn sample is extremely weak.

It was confirmed that the magnetization M _s in the Mn ₃ Sn sample was about 1/236 to 1/1389 of the ferromagnetic material shown in FIG. Thereby, it can be seen that Mn ₃ Sn has a remarkably smaller leakage magnetic field than the ferromagnetic material used in the conventional thermoelectric conversion element.

In FIG. 6, Mn ₃ Sn as Example 1 has the highest voltage S _xy per unit temperature of 0.75 [μV / K] when it is 200 [K], and also when it is 300 [K]. The voltage S _xy per unit temperature is 0.46 [μV / K], which is similar to that of Comparative Example 2 (ferromagnetic FePd), which is the second highest value after Comparative Example 1 (FePt) and Comparative Example 2 (FePd). It was confirmed that.

The value of voltage S _xy per unit temperature obtained in Example 1 is extremely large as a magnetic material, and per unit temperature found in at least MnGa, Mn ₂ Ga, and Co / Ni ferromagnets in Comparative Examples. It was confirmed that the value was larger than the value of the voltage _Sxy . The voltage S _xy per unit temperature is generally considered to be proportional to the magnetization M _s , and the proportional coefficient Q _s takes a value between about 0.1 to 1 [μV / TK] in the ferromagnetic material. However, it was confirmed that Mn ₃ Sn, which is Example 1, takes a value about three orders of magnitude larger than that of the ferromagnetic material due to the influence of the minute spontaneous magnetization.

When Mn ₃ Sn is used as the thermoelectric conversion element 2 as described above, a voltage S _xy per unit temperature comparable to or higher than that of the ferromagnetic material can be obtained, and the ferromagnetic material used in the conventional thermoelectric conversion element. It was confirmed that the leakage magnetic field can be significantly smaller than the body.

(4) Operation and Effect In the above configuration, the thermoelectric conversion device 1 includes the thermoelectric conversion element 2 made of a non-collinear antiferromagnetic material having a non-collinear spin structure, and has a surface facing the thermoelectric conversion element. A temperature difference is given by flowing a heat flow in the direction perpendicular to the minute magnetization direction Ar2. Thereby, in the thermoelectric conversion device 1, based on the temperature difference which arises in the heat flow direction Ar1 orthogonal to the minute magnetization direction Ar2 in the surface of the thermoelectric conversion element 2 by the abnormal Nernst effect, the minute magnetization direction Ar2 and the heat flow direction Ar1 respectively. A voltage can be generated in the orthogonal direction.

  Moreover, in the thermoelectric conversion device 1, since the thermoelectric conversion element 2 is formed of an antiferromagnetic material that does not have strong magnetization such as a ferromagnetic material, the leakage magnetic field is higher than that of a conventional thermoelectric conversion device using a ferromagnetic material. Can be significantly suppressed. Thus, in the thermoelectric conversion device 1, since the leakage magnetic field can be remarkably suppressed as compared with a conventional thermoelectric conversion device using a ferromagnetic material, a plurality of thermoelectric conversion elements 2 can be highly integrated, or other Even if the peripheral devices are brought close to each other, it is possible to prevent the adjacent thermoelectric conversion element 2 and the peripheral devices from being affected by the leakage magnetic field.

  Therefore, in the thermoelectric conversion device 1, the gap between the thermoelectric conversion elements 2 is reduced and densely arranged within a limited area in which the heat flow flows without considering the influence of the leakage magnetic field between the adjacent thermoelectric conversion elements 2. Therefore, more thermoelectric conversion elements 2 can be mounted per unit area, and thus the power generation efficiency per unit area can be improved as compared with the conventional thermoelectric conversion device using a ferromagnetic material.

  In addition, since the thermoelectric conversion device 1 is less likely to be affected by a leakage magnetic field to peripheral devices, the thermoelectric conversion device 1 is easily affected by magnetism, and the peripheral thermoelectric conversion device using a ferromagnetic material cannot be brought close to the peripheral device. Since it can be arranged close to the device, it can be arranged with a peripheral device in a precise manner, and furthermore, a voltage can be generated using a heat flow generated from the peripheral device.

(5) Thermoelectric Conversion Device According to Other Embodiments In the above-described embodiment, the thermoelectric conversion device 1 including the rectangular parallelepiped thermoelectric conversion element 2 has been described as shown in FIG. However, the thermoelectric conversion elements 24 and the connection elements 25 are alternately arranged in parallel, as shown in FIG. It may be a thermoelectric conversion device 21 in which a plurality of connection elements 25 are electrically connected in series.

  In this case, the thermoelectric conversion device 21 has a configuration in which the power generator 23 formed in a meandering shape is installed on the substrate 22, and heat flows from the back surface of the substrate 22 toward the power generator 23. A temperature difference can be given in the direction perpendicular to the surface of the substrate 22. Thereby, the thermoelectric conversion device 21 can generate an abnormal Nernst effect in the power generation body 23 and generate a voltage in the power generation body 23. Here, the substrate 22 has, for example, an MgO single layer or a structure in which an MgO layer is laminated on an Au layer, and the power generator 23 that extends in a meandering manner along the installation surface 23a facing the back surface to which heat flow is applied. Is installed.

  In the power generation body 23, a plurality of thermoelectric conversion elements 24 having a longitudinal direction and a plurality of connection elements 25 having a longitudinal direction are alternately arranged in parallel, and the thermoelectric conversion elements 24 and the connection elements 25 are electrically connected in series. It has a connected configuration. The thermoelectric conversion element 24 is made of the antiferromagnetic material described above in “(1) About the antiferromagnetic material used for the thermoelectric conversion element”, and when a temperature difference occurs based on the heat flow applied to the back side of the substrate 22. Due to the abnormal Nernst effect, a voltage can be generated in a direction perpendicular to the in-plane micromagnetization direction Ar2 and the heat flow direction Ar1 (arrow x1 direction).

  Here, in the thermoelectric conversion element 24, in-plane micromagnetization is directed in the longitudinal direction (arrow x1, x2 direction) and the direction (arrow z2 direction) orthogonal to the heat flow direction Ar1. Thereby, in the thermoelectric conversion element 24, since the minute magnetization direction Ar2 is the arrow z2 direction, when a temperature difference is caused by the heat flow flowing from the back side of the substrate 22, a voltage is generated in the arrow x1 direction along the longitudinal direction. obtain.

In the case of this embodiment, the connection element 25 is also made of the antiferromagnetic material described in “(1) Antiferromagnetic material used for thermoelectric conversion element”, similarly to the thermoelectric conversion element 24, and the substrate 22. When the temperature difference is generated based on the heat flow applied to the back surface side of the substrate, the abnormal Nernst effect causes the in-plane micromagnetization direction Ar2 and the heat flow direction Ar1 to be orthogonal to the thermoelectric conversion element 24 (in the direction indicated by the arrow x2). ) May generate a voltage. Connecting element 25 is perpendicular to the longitudinal direction (arrow x1, x2 direction) and the heat flow direction Ar @ 1, and the thermoelectric conversion element 24 is directed micromagnetization M _s in-plane toward the opposite direction (arrow z1 direction) Yes. Thereby, in the connection element 25, since the micromagnetization direction Ar2 is the arrow z1 direction opposite to the thermoelectric conversion element 24, if a temperature difference is caused by the heat flow flowing from the back surface side of the substrate 22, the thermoelectricity along the longitudinal direction is generated. A voltage can be generated in the direction of the arrow x2 opposite to the conversion element 24.

  Here, the connection element 25 disposed between the adjacent thermoelectric conversion elements 24 includes one end side of one thermoelectric conversion element 24 and the other end of another thermoelectric conversion element 24 adjacent to the one thermoelectric conversion element 24. Are electrically connected in series, and a voltage generated in one thermoelectric conversion element 24 can be applied to another thermoelectric conversion element 24. In this way, the power generation body 23 can generate a voltage at each of the thermoelectric conversion element 24 and the connection element 25 and increase the output voltage.

  In addition to such a configuration, since the thermoelectric conversion element 24 and the connection element 25 are formed in the power generation body 23 by an antiferromagnetic material that does not have strong magnetization such as a ferromagnet, the thermoelectric conversion element 24 and the connection element. 25 is not easily affected by the leakage magnetic field of each other. Therefore, in the power generation body 23, the gap between the thermoelectric conversion element 24 and the connection element 25 is extremely small and is densely arranged on the substrate 22.

  Note that such a thermoelectric conversion device 21 uses a photolithography technique or the like to produce a power generator 23 that extends in a meandering manner on a substrate 22, and then adjusts the N pole and S in accordance with the shape of the power generator 23. The magnetic field can be manufactured by controlling the in-plane micromagnetization direction Ar2 of the thermoelectric conversion element 24 and the connection element 25 by bringing an external magnetic field in which poles are arranged in advance closer to the surface of the produced power generation body 23.

  In the above configuration, the thermoelectric conversion device 21 also includes the thermoelectric conversion element 24 and the connection element 25 made of an antiferromagnetic material having a non-collinear spin structure, and is in-plane with respect to the thermoelectric conversion element 24 and the connection element 25. A temperature difference is given by flowing a heat flow in a direction perpendicular to the minute magnetization direction Ar2. Thereby, in the thermoelectric conversion device 1, the micro magnetization direction Ar2 and the heat flow are generated based on the temperature difference generated in the heat flow direction Ar1 orthogonal to the micro magnetization direction Ar2 in the plane of the thermoelectric conversion element 24 and the connection element 25 due to the abnormal Nernst effect. A voltage can be generated in a direction orthogonal to the direction Ar1.

  In the thermoelectric conversion device 21, in particular, the thermoelectric conversion element 24 and the connection element 25 are formed of an antiferromagnetic material that does not have strong magnetization such as a ferromagnetic material, so that the conventional thermoelectric conversion device using a ferromagnetic material is used. However, even if the gap between the thermoelectric conversion element 24 and the connection element 25 is made small and highly integrated, the influence of the leakage magnetic field on the adjacent thermoelectric conversion element 24 and the connection element 25 can be suppressed. Can be prevented.

  Therefore, in the thermoelectric conversion device 21, the gap between the thermoelectric conversion element 24 and the connection element 25 is within a limited area in which the heat flow flows without considering the influence of the leakage magnetic field of the adjacent thermoelectric conversion element 24 and the connection element 25. Therefore, more thermoelectric conversion elements 24 and connection elements 25 can be mounted per unit area, and thus more unit than a conventional thermoelectric conversion device using a ferromagnetic material. The power generation efficiency per area can be improved.

  In the above-described embodiment, the power generation body 23 in which the connection element 25 is also formed of an antiferromagnetic material in addition to the thermoelectric conversion element 24 has been described. However, the present invention is not limited to this. It is good also as an electric power generation body which formed with the ferromagnetic material and formed only the thermoelectric conversion element 24 with the antiferromagnetic material. In the power generation body 23, the thermoelectric conversion element 24 and the connection element 25 may be formed of different antiferromagnetic materials, or the connection element 25 may be formed of a conductive material having no magnetization.

1, 21 Thermoelectric conversion device 2, 24 Thermoelectric conversion element 22 Substrate 23 Power generator 25 Connection element

Claims (5)

A thermoelectric conversion element made of an antiferromagnetic material having a non-collinear spin structure is provided,
In the thermoelectric conversion element, a voltage is generated due to a temperature difference generated in a direction perpendicular to the in-plane micromagnetization direction due to an abnormal Nernst effect. The thermoelectric conversion device according to claim 1, wherein the antiferromagnetic material is any one of Mn ₃ Sn, Mn ₃ Ge, and Mn ₃ Ga. The antiferromagnetic material is
Cubic or tetragonal and Mn and Ni compounds,
a cubic alloy containing γ-phase Mn,
The thermoelectric conversion device according to claim 1, wherein the thermoelectric conversion device is any one of three of a cubic alloy containing Fe. The thermoelectric conversion element having a longitudinal direction and a connecting element having a longitudinal direction are alternately provided in parallel on a substrate,
The power generator is
One end of the one thermoelectric conversion element and the other end of the other thermoelectric conversion element adjacent to the one thermoelectric conversion element are electrically connected in series by the connection element, and meanderingly on the substrate It is arrange | positioned. The thermoelectric conversion device of any one of Claims 1-3 characterized by the above-mentioned. The connection element is made of an antiferromagnetic material having a non-collinear spin structure,
The thermoelectric conversion device according to claim 4, wherein in the thermoelectric conversion element and the connection element, in-plane minute magnetization directions are opposite to each other, and a voltage generated due to a temperature difference is generated in the opposite direction.

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