JP7606243B2 - Thermopile type temperature control element - Google Patents

Description

The present invention relates to a thermopile-type temperature control element that can directly convert electrical energy into thermal energy, and in particular to a thermopile-type temperature control element that uses a magnetic material that generates an anisotropic magnetic Peltier effect.

The interaction between electric current and heat flow in metals and semiconductors is called the thermoelectric effect, and the Seebeck effect, which creates a voltage from a temperature difference, and the Peltier effect, which heats and cools with electric current, have been known for a long time. The history of the thermoelectric effect began with the discovery of the Seebeck effect in 1821 by German physicist and physician Thomas Seebeck. Thirteen years later, in 1834, the Peltier effect was first observed by French physicist Jean-Charles Peltier. The Peltier effect is a phenomenon in which a heat flow occurs along the flow of electric current in a metal or semiconductor. When two types of materials with different conversion efficiencies from electric current to heat flow (Peltier coefficients) are joined, heat is generated or absorbed at the joint interface depending on the direction of the current.

The Peltier effect has several advantages, such as the ability to switch between heating and cooling simply by changing the direction of electric current, the fact that it is quiet and reliable because it has no moving parts, and the ability to be miniaturized, and it is expected to be applied to a wide range of purposes as a thermal control technology.
Meanwhile, in the field of spintronics, a promising candidate for next-generation electronics technology, the properties of electron spin (magnetism) and the interactions between electric current and heat flow are being actively studied from both fundamental and applied perspectives. It is known that in magnetic materials, the flow of electric current and heat flow is affected by the direction of magnetization due to the effect of spin. A representative example of such a phenomenon is the anisotropic magnetoresistance effect, in which the electrical resistance of a magnetic material changes depending on the angle between the magnetization and the electric current. Similarly, the Seebeck effect in magnetic materials also depends on the direction of magnetization. The reverse process, i.e., the Peltier effect, which changes depending on the magnetization direction, has also been observed experimentally.

That is, as shown in Patent Document 1 and Non-Patent Document 1, in a magnetic material in which the anisotropic magnetic Peltier effect occurs, the Peltier coefficient differs depending on whether the magnetization is parallel to the current or perpendicular to it. By utilizing this property, it is possible to create a non-uniform magnetization distribution in the magnetic material, thereby generating heat or absorbing heat as if materials with different Peltier coefficients were joined together. In other words, a magnetic virtual junction can cause a temperature change due to the Peltier effect in a single material with no material interface.

On the other hand, electronic devices such as LSIs and μ-processors have maintained a trend of doubling the number of transistors on an integrated circuit every 18 months for 50 years under Moore's Law, which was announced in 1965. With the continuous advancement of integrated circuit technology, the integration density of integrated circuits has improved by more than seven orders of magnitude in the last 50 years. Today, research and development is being actively promoted for the era of quantum computing, and it is said that the size of a single transistor is approaching that of a single atom, and Moore's Law is approaching its limit.
The increasing integration density of integrated circuits has led to an increase in failure rate and a decrease in reliability due to an increase in heat density, making it difficult to obtain sufficient cooling capacity using conventional heat sinks and refrigerants.

JP 2018-190780 A

“Observation of anisotropic magneto-Peltier effect in nickel”, Ken-ichi Uchida et.al., Nature, DOI: 10.1038/s41586-018-0143-x, Published: May 22, 2018, Japan time

The object of the present invention is to provide an improved thermopile-type temperature control element that has a thermopile structure using a magnetic material that generates an anisotropic magnetic Peltier effect, and that increases the cooling and heating capacity.

The inventors conducted extensive research to solve the above problems, and discovered that by using the properties of the anisotropic magnetic Peltier effect, in which heat generation and absorption occurs at the boundary between regions where the relative angles between magnetization and current are different (when a ferromagnetic body with a bent portion is uniformly magnetized, a heat source occurs at the corner), and concentrating the "corners" where temperature changes of the same sign occur in one place, it is possible to obtain a large cooling/heating capacity by forming a thermopile using the anisotropic magnetic Peltier effect, thus completing the present invention. Unlike conventional Peltier effect thermopiles that are made up of junctions of different materials, the use of the anisotropic magnetic Peltier effect makes it possible to form a thermopile using a single material without junctions. The cooling/heating capacity of the anisotropic magnetic Peltier effect obtained by forming a thermopile is proportional to the number of "corners" concentrated.

[1] The thermopile-type temperature control element of the present invention is characterized in that, as shown in Figures 1 and 2, a plurality of conductive magnetic bodies 10, each of which has a conductive magnetic body that generates a temperature change due to the anisotropic magnetic Peltier effect as a unit element, a current application means 20 that is provided so as to be able to apply a current to each of the plurality of conductive magnetic bodies, and the plurality of conductive magnetic bodies are integrated in a structure in which the boundaries between regions where the relative angles between magnetization and current are different are made into heat generation/absorption regions, and the heat generation/absorption regions in the conductive magnetic bodies of the unit elements are substantially gathered in one place.
Here, "a structure in which the heat generation/absorption areas are substantially concentrated in one place" means that the distance between the heat generation/absorption areas of the conductive magnetic material of the adjacent unit elements is close enough to make the thermal resistance negligible, as shown in Figures 1 and 2, for example.

[2] A thermopile-type temperature control element as described in [1], characterized in that the accumulation of heat generating and absorbing regions in the conductive magnetic material of the unit element is performed in an in-plane region with respect to the surface formed by the conductive magnetic material.
[3] A thermopile-type temperature control element according to [1] or [2], characterized in that the accumulation of heat generating and absorbing regions in the conductive magnetic material of the unit element is performed in a region perpendicular to the surface formed by the conductive magnetic material.

[4] A thermopile-type temperature control element described in any one of [1] to [3], characterized in that the magnetization direction in the conductive magnetic body of the unit element has a first magnetization region having a magnetization direction substantially parallel to the axial direction of the conductive magnetic body, with the heat generation/heat absorption region as a boundary, and a magnetization direction inclined obliquely in-plane or out-of-plane to the first magnetization region, or perpendicular to the first magnetization region.
[5] The thermopile-type temperature control element according to [4], wherein the conductive magnetic body of the unit element has a V-shape or an L-shape with the heat generating/absorbing region as a vertex.
[6] A thermopile-type temperature control element according to [5], characterized in that the conductive magnetic body of the unit element has two or more conductive magnetic bodies on a surface formed by the conductive magnetic bodies.

[7] The thermopile-type temperature control element of the present invention is characterized in that, as shown in Figures 11 and 12, a plurality of conductive magnetic bodies (110, 140) each having a unit element being a conductive magnetic body in which a temperature change occurs due to the anisotropic magnetic Peltier effect, a current application means 120 provided so as to be able to apply a current to each of the plurality of conductive magnetic bodies, and a structure in which the boundaries between regions in which the relative angles between magnetization and current are different are made into heat generation/absorption regions, and the heat generation/absorption regions 130 in the conductive magnetic body of the unit element are arranged in two or more discrete locations arranged substantially in a straight line, and the plurality of conductive magnetic bodies are integrated.
Here, "arranged substantially in a straight line" means that, as shown in FIG. 12, for example, the distance d between the heat generating/absorbing region and the opposing heat generating/absorbing region in the conductive magnetic body of an adjacent unit element is about half the distance D between the heat generating/absorbing region and the adjacent heat generating/absorbing region in the conductive magnetic body of the same unit element, and therefore the thermal effect of the heat generating/absorbing region of the conductive magnetic body of the same unit element on the heat generating/absorbing region of the conductive magnetic body of the adjacent unit element can be ignored, making it possible to efficiently improve the cooling/heating capacity in the center of the thermopile structure.

[8] The thermopile-type temperature control element according to any one of [1] to [7], characterized in that the conductive magnetic body is made of a single material.
[9] The thermopile-type temperature control element according to any one of [1] to [8], characterized in that the conductive magnetic body is made of a ferromagnetic body, a ferrimagnetic body or an antiferromagnetic body.
[10] The thermopile-type temperature control element according to any one of [1] to [8], characterized in that the conductive magnetic body is made of nickel or an alloy containing 40 wt % or more of nickel.
[11] The thermopile-type temperature control element according to any one of [1] to [8], characterized in that the conductive magnetic body is made of nickel or a Ni-Fe alloy containing 40 wt % or more of nickel.

[12] An electronic device using a thermopile-type temperature control element according to any one of [1] to [8].

According to the present invention, by utilizing the properties of the anisotropic magnetic Peltier effect, in which heat generation/absorption occurs at the boundary between regions where the relative angles of magnetization and current are different (when a uniformly magnetized linear ferromagnetic body is bent into a V- or L-shape, a heat source occurs near the tip of the V- or L-shape), a heat generation/absorption mechanism is formed by bending multiple linear bodies into a V- or L-shape so that the "tips" where temperature changes of the same sign occur are essentially concentrated in one place, which can generate a larger temperature change than the anisotropic magnetic Peltier effect in a conventional single wire.

1 is a perspective view of the configuration of a cross-shaped thermopile showing one embodiment of the present invention. 1 is a plan view of a cross-shaped thermopile showing one embodiment of the present invention. 1 is an explanatory diagram of a five-branch thermopile showing one embodiment of the present invention. 1 is an explanatory diagram of a six-branch thermopile showing one embodiment of the present invention. FIG. 1A is an overall view of a lock-in thermography measurement system, and FIG. 1B is a diagram illustrating applied current and thermal image output. FIG. 1 is a diagram illustrating the flow of signal processing in the lock-in thermography method used for measuring the anisotropic magnetic Peltier effect. 1 is an explanatory diagram of temperature modulation of a cross-shaped thermopile showing one embodiment of the present invention. This is an explanatory diagram of the lock-in frequency (input current frequency) dependency, showing thermal images of the temperature amplitude component and phase component of each frequency. 1 is a graph illustrating the lock-in frequency (frequency of the input current) dependence of the temperature amplitude component and phase component. FIG. 1 is an explanatory diagram of measurement results obtained by a normal thermography method in a steady state. 1 is a perspective view showing the configuration of a zigzag thermopile according to one embodiment of the present invention; 1 is a plan view of a zigzag thermopile showing one embodiment of the present invention.

The following are definitions of technical terms used in this specification.
(1) Anisotropic magnetic Peltier effect The anisotropic magnetic Peltier effect is a Peltier effect that appears in ferromagnetic materials and depends on the relative angle between magnetization and electric current. Heat absorption and release occurs at the boundary between regions where the angles of magnetization and electric current are different, so it occurs even if there is no junction interface between different materials. The Peltier coefficient can be anisotropically controlled by the magnetization angle alone.
(2) Thermopile A thermopile is an element that directly converts thermal energy into electrical energy and vice versa. Conventional thermopiles using the Seebeck effect or Peltier effect consist of multiple thermocouples (a junction of different materials with different Seebeck and Peltier coefficients) connected in series or parallel, and the output is proportional to the number of thermocouples. This invention proposes a thermopile structure for the anisotropic magnetic Peltier effect, and is characterized by the fact that a thermopile can be constructed from a single material simply by designing the relative angle between the current and magnetization, without creating a thermocouple structure.

Fig. 1 is a perspective view of the configuration of a cross-shaped thermopile showing one embodiment of the present invention, and Fig. 2 is a plan view of the cross-shaped thermopile showing one embodiment of the present invention.
In the figure, the conductive magnetic body 10 is made of, for example, nickel or a Ni-Fe alloy containing 40 wt% or more of nickel, and is a combination of multiple V-shaped or L-shaped wires or thin films. The conductive magnetic body 10 has a V-shaped or L-shaped tip 12 and a region of a first magnetization direction 14 and a second magnetization direction 16 with the vicinity of the tip 12 as a boundary. The first magnetization direction 14 is parallel to the direction from the tip of the conductive magnetic body 10 to one end. The second magnetization direction 16 is perpendicular to the direction from the tip of the conductive magnetic body 10 to the other end.

The current application means 20 is a DC power supply device that supplies a current to the conductive magnetic body 10 so that a current Jc flows in the illustrated flow direction 24. The wiring 22 connects the conductive magnetic bodies 10, which are unit elements, in series, and is made of a conductive wire such as copper, aluminum, silver, etc. It is also possible to use the same material for the wiring 22 as the conductive magnetic bodies 10, which allows the thermopile to be constructed entirely from a single type of material.
The heat generation/absorption region 30 is a region formed by bending multiple linear bodies into a V-shape, utilizing the property of the anisotropic magnetic Peltier effect, in which when a uniformly magnetized linear ferromagnetic body is bent into a V-shape or an L-shape, a heat source is generated near the tip of the V-shape or L-shape, so that the "tips" where temperature changes of the same sign occur are substantially concentrated in one place. According to the anisotropic magnetic Peltier effect, heat generation/absorption occurs at the boundary between regions where the relative angles between magnetization and current are different.

1 shows a case where the heat generating/absorbing regions 30 in the conductive magnetic body 10 of the unit element are integrated in an area within the plane of the surface formed by the conductive magnetic body 10. The heat generating/absorbing regions 30 in the conductive magnetic body of the unit element may be integrated in an area perpendicular to the surface formed by the conductive magnetic body 10. In this case, the conductive magnetic bodies 10 are assembled in a stacked state.
In the heat generation/absorption region 30, when the current Jc flows in the direction 24 shown in Fig. 1(A), heat generation 32 occurs. In contrast, when the current Jc flows in the direction 24 shown in Fig. 1(B), heat absorption 34 occurs. However, Fig. 1 shows behavior when the sign of the anisotropy of the Peltier coefficient is the same as that of nickel, and if a material showing an anisotropy of the Peltier coefficient with an opposite sign to that of nickel is used, the relationship between heat generation and absorption when the current direction is fixed is reversed.
In addition, in Figure 1, the total heat generation/absorption amount of the cross-shaped thermopile structure is represented as |Q| for the convenience of indicating that it is a heat generation/absorption region 30, and is quantitatively different from the heat generation/absorption amount Q per one piece shown in Figure 2.

In a device configured in this way, when a uniformly magnetized linear ferromagnetic material is bent into a V-shape or L-shape, a heat source is generated near the tip of the V-shape or L-shape, and in order to generate the largest temperature change per ferromagnetic metal wire with isotropic magnetic properties using the anisotropic magnetic Peltier effect, it is necessary to have adjacent regions where the relative angles between magnetization and current differ by 90 degrees, as shown in Figures 2 (A) and (B). When creating a thermopile structure using uniformly magnetized ferromagnetic wires, the most efficient is a cross-shaped structure made of L-shaped ferromagnetic material, which can be easily realized by applying an external magnetic field. If the amount of heat generated/absorbed per wire is Q, the total amount of heat generated/absorbed in the cross-shaped thermopile structure is |4Q|, which is proportional to the number of wires.

FIG. 3 is an explanatory diagram of a five-branch thermopile showing one embodiment of the present invention.
When the linear ferromagnetic body 40 is bent in a V-shape, the thermopile of the present invention can be realized by combining the magnetic anisotropy of the five-branch thermopile shown in Fig. 3 with a first ferromagnetic body branch 44 extending from the V-shaped tip 42 toward one end and a second ferromagnetic body branch 46 extending toward the other end. That is, in the first ferromagnetic body branch 44, the magnetization direction is parallel to the direction from the tip 42 toward one end. In the second ferromagnetic body branch 46, the magnetization direction is perpendicular to the direction from the tip 42 toward the other end. The V-shaped bent arrow 48 indicates the flow direction of the current Jc supplied to the linear ferromagnetic body 40 from a DC power supply device (not shown) via wiring (not shown).

By making use of magnetic anisotropy to create such a magnetization distribution, the angle at which each linear ferromagnetic body is bent into a V shape can be adjusted to, for example, 72 degrees, eliminating the need to fix it at 90 degrees. This makes it possible to generate heat proportional to the number of integrated corners, so the total amount of heat generated/absorbed in the thermopile structure of FIG. 3 is |5Q|.
In principle, the present invention is not limited to two-dimensional integration, but may be implemented in a three-dimensional manner. The five-branch magnetization distribution shown in Fig. 3 cannot be realized by simply applying a uniform external magnetic field to an isotropic ferromagnetic material.

Figure 4 is an explanatory diagram of a six-branch thermopile showing one embodiment of the present invention, where (A) shows a configuration in which different magnetization directions are combined in a first ferromagnetic branch extending from the V-shaped tip toward one end and a second ferromagnetic branch extending toward the other end, and (B) shows the case in which the thermopile is uniformly magnetized.
When the linear ferromagnetic body 50 is bent in a V-shape, the thermopile of the present invention can be realized by combining the magnetic anisotropy of the six-branch thermopile shown in Fig. 4(A) with a first ferromagnetic body branch 54 extending from the V-shape tip 52 toward one end and a second ferromagnetic body branch 56 extending toward the other end. That is, in the first ferromagnetic body branch 54, the magnetization direction is parallel to the direction extending from the tip 52 toward one end. In the second ferromagnetic body branch 56, the magnetization direction is perpendicular to the direction extending from the tip 52 toward the other end. The V-shaped bent arrow 58 indicates the flow direction of the current Jc supplied to the linear ferromagnetic body 50 from a DC power supply (not shown) via wiring (not shown).
By creating such a magnetization distribution, the angle at which each linear ferromagnetic body is bent into a V shape can be set to, for example, 60 degrees. This makes it possible to generate/absorb heat in proportion to the number of integrated corners, so the total amount of heat generated/absorbed in the thermopile structure shown in FIG. 4A is |6Q|.

FIG. 4B shows a structure in which six linear ferromagnetic bodies bent into a V-shape are accumulated and uniformly magnetized.
When the linear ferromagnetic body 60 is bent in a V-shape, the thermopile of the present invention can be realized in a six-branch thermopile shown in FIG. 4B with a first ferromagnetic body branch 65 extending from the V-shape tip 64 toward one end and a second ferromagnetic body branch 66 extending toward the other end. That is, in the four linear bodies 60 excluding the linear bodies 61 and 62, the magnetization direction in the first ferromagnetic body branch 65 is oblique to the direction from the tip 64 toward one end. In the second ferromagnetic body branch 66, the magnetization direction is perpendicular to the direction from the tip 64 toward the other end. Here, the relative angle difference between the current and the magnetization in the linear body 60 is no longer 90 degrees, so that the temperature change is small (Q>q). The arrow 68 bent in a V-shape indicates the flow direction of the current Jc supplied to the linear ferromagnetic body 60 from a DC power supply device (not shown) via wiring (not shown).
On the other hand, in the case of the wires 61 and 62, although the linear ferromagnetic material is bent into a V shape, the Peltier coefficients of the first ferromagnetic material branch extending from the V-shaped tip 64 toward one end and the second ferromagnetic material branch extending toward the other end are the same, and therefore no temperature change can be produced by the anisotropic magnetic Peltier effect.
Therefore, under the limited condition that a linear ferromagnetic body bent into a V-shape or L-shape is uniformly magnetized by an external magnetic field, a cross structure consisting of four linear ferromagnetic bodies is most efficient.

FIG. 5A is an overall diagram of the lock-in thermography measurement system, and FIG. 5B shows the applied current and the thermal image output.
The lock-in thermography measurement system is composed of a sample 70 to be measured, an infrared camera 80, a source meter 90, and an arithmetic and control system 100. Here, thermography is a measurement method for detecting the spatial distribution of infrared rays radiated from the surface of a material. Since the radiation energy of infrared rays depends on the temperature of the material, the temperature distribution of the material can be obtained as image information by performing appropriate calibration.

The sample 70 is, for example, a thermopile having an anisotropic magnetic Peltier effect as shown in FIGS.
The infrared camera 80 is a camera for visualizing infrared radiation emitted from an object. Since the amount of infrared radiation increases in proportion to the fourth power of absolute temperature, changes in the temperature of an object can be visualized as changes in the amount of infrared radiation. This type of temperature distribution measurement method is called thermography. Infrared cameras are either a cooled type that uses a semiconductor sensor that detects infrared radiation in a wavelength range of about 3 to 5 μm, or a non-cooled type that uses a microbolometer that detects infrared radiation in a wavelength range of about 7 to 14 μm.

The SourceMeter 90 provides both precision voltage and current sourcing and measurement capabilities, and operates as a voltage source, current source, voltmeter, ammeter, and ohmmeter. The SourceMeter 90 offers many advantages over a collection of individual measuring instruments, including reduced test times by eliminating GPIB transfer times, simplified remote programming, and protection of the device under test from damage due to accidental overload, overheating, etc. Both current and voltage sourcing are programmable, with readback capabilities, providing the advantage of greatly improving device measurement quality.
The arithmetic and control system 100 selectively extracts and visualizes only the temperature change that changes over time at the same frequency as the current by using Fourier analysis.

In the lock-in thermography measurement system configured in this manner, as shown in FIG. 5B, a source meter 90 is used to apply a periodically changing current to the sample 70 while an infrared camera 80 is used to measure the surface temperature distribution.
Then, by subjecting the temperature distribution data observed by the arithmetic and control system 100 to Fourier analysis, it is possible to selectively extract and visualize only the temperature changes that change over time at the same frequency as the current applied by the source meter 90. This makes it possible to realize highly sensitive measurement of the thermoelectric effect, and by increasing the frequency of the current, it is possible to suppress the effects of thermal diffusion and identify the positions of the heat generation source and heat sink.

5(A) and (B), an amplitude component 102 and a phase component 104 of a lock-in thermal image of a measurement object are obtained. The amplitude component 102 represents the spatial distribution of the magnitude of the temperature change occurring in response to an input current, and the phase component 104 represents the spatial distribution of the sign of the temperature change and the time delay due to thermal diffusion.
Using this lock-in thermography measurement system, it is possible to measure in detail the temperature changes that occur when a current is passed through the sample 70 and to examine the magnetic field dependence and spatial distribution, thereby isolating and evaluating various thermal response phenomena.

FIG. 6 is an explanatory diagram of the lock-in thermography method showing the measurement mode of the anisotropic magnetic Peltier effect, in which (A) is an infrared image, (B) is the applied signal waveform, (C) is Fourier analysis, (D) is the amplitude component of the lock-in thermal image, and (E) is the phase component of the lock-in thermal image.
An infrared image as shown in Fig. 6(A) can be obtained by using, for example, an imaging system using an infrared camera as shown in Fig. 5(A) and a square wave drive current Jc as shown in Fig. 6(B). The infrared image is an infrared image of a sample 70, and changes according to the current Jc supplied from a DC power supply 92 as one of the functions of the source meter. The drive current waveform is, for example, a square wave current signal with a frequency of 10 Hz and a drive current amplitude of ±1 A, and is applied to a sample 70 used in a demonstration experiment of the anisotropic magnetic Peltier effect as shown in Fig. 6(A).
The infrared image obtained by the infrared camera 80 is a planar image of the sample 70 represented by X and Y coordinates, and is converted into image information, such as 30 frames per second. The infrared image information is then subjected to Fourier analysis as shown in Fig. 6(C) and is decomposed into amplitude and phase components of a lock-in thermal image. Fig. 6(D) shows an amplitude component image 103 of the lock-in thermal image, and (E) shows a phase component image 105 of the lock-in thermal image.

This type of infrared image analysis allows for highly sensitive thermal imaging measurements of temperature changes that occur in proportion to the input signal, with a temperature resolution of, for example, 0.1 mK. This allows for systematic evaluation of the temperature, magnetic field, and frequency dependence of various thermoelectric effects (temperature changes in response to electric current), including the Peltier effect. It also allows for simultaneous measurement of multiple samples, which has the effect of enabling high-throughput material exploration of thermoelectric materials.

Figure 7 is an explanatory diagram of the temperature modulation of a cross-shaped thermopile showing one embodiment of the present invention, where (A) is a temperature amplitude image, (B) is a phase difference image between the applied signal waveform and the temperature change, (C) is an infrared image in a steady state, (D) is an amplitude component showing odd dependence on the magnetization direction, (E) is the phase component of (D), (F) is an amplitude component showing even dependence on the magnetization direction, (G) is the phase component of (F), (H) is the amplitude component of a thermal image obtained by subtracting a background signal that does not depend on the magnetization direction from the signal showing even dependence on the magnetization direction to extract only the signal resulting from the anisotropic magnetic Peltier effect, and (I) is the phase component of (H).

Next, a description will be given of temperature modulation in a cross-shaped thermopile according to an embodiment of the present invention. Sample 70 is made of four linear ferromagnetic bodies bent into an L-shape and arranged in a cross shape as shown in Figures 1 and 2, and is specifically made of Ni wires.
The measurement is performed using a lock-in thermography measurement system while passing a square wave AC current through the sample 70. Only when the Ni is magnetized, a temperature change occurs that is concentrated at the center (the corner of each Ni) formed by substantially gathering the sharp points formed by bending the multiple linear bodies into a V shape, and this is due to the anisotropic magnetic Peltier effect.

Figure 8 is an explanatory diagram of the lock-in frequency (frequency of input current) dependence of the anisotropic magnetic Peltier effect, showing images of the temperature amplitude component and phase component of each frequency. In Figure 8, (A1) to (A10) are temperature amplitude images, and (B1) to (B10) are the phase difference between the applied signal waveform and the temperature change, and the lock-in frequencies are 25.0 Hz, 16.7 Hz, 12.5 Hz, 10.0 Hz, 5.0 Hz, 2.0 Hz, 1.0 Hz, 0.5 Hz, 0.2 Hz, and 0.1 Hz, respectively. As the lock-in frequency decreases, the temperature change increases monotonically. When a current with a square wave amplitude of 1.0 A is applied to a Ni wire with a cross section of 0.2 mm square, the temperature change reaches 150 mK at 0.1 Hz, which is almost in a steady state. This result was measured with a magnetic field strength H of ±3 kOe (≒ ±240 kA/m), and the Ni wires that make up the cross-shaped thermopile are uniformly magnetized in the magnetic field direction.

9 is a graph for explaining the lock-in frequency (frequency of input current) dependency of temperature change due to the anisotropic magnetic Peltier effect, where (A) shows the value at the center position (center of the cross structure: region C) of the temperature amplitude image in Fig. 8, and (B) shows the value in region C of the phase image in Fig. 8. The position of region C is defined in Fig. 8 (A1) and (A6).
In the low lock-in frequency range (e.g., below 2 Hz), the temperature distribution is close to the steady state. In contrast, in the high lock-in frequency range (e.g., above 2 Hz), the temperature distribution is in a transient state where thermal diffusion is suppressed. From the results in the high lock-in frequency range, it can be seen that the heat source and heat sink are located at the center of the cross structure, which is consistent with the behavior predicted from the anisotropic magnetic Peltier effect.

FIG. 10 is an explanatory diagram of the measurement results obtained by a normal thermography method in a steady state.
Because the thermopile structure is capable of producing large temperature changes, it has been shown that the anisotropic magnetic Peltier effect can be measured using conventional thermography rather than lock-in thermography.

Figure 11 is a perspective view of the configuration of a zigzag thermopile showing one embodiment of the present invention. Figure 12 is a plan view of a zigzag thermopile showing one embodiment of the present invention. The above discussion of the anisotropic magnetic Peltier effect in the cross-shaped thermopile also applies to the zigzag type.

In the figure, the conductive magnetic body 110 is made of, for example, nickel or a Ni-Fe alloy containing 40 wt % or more of nickel, and has a linear or thin zigzag shape. The conductive magnetic body 110 has a zigzag tip 112 close to the adjacent conductive magnetic body 140, a first magnetization direction 114 and a second magnetization direction 116 with the vicinity of the tip 112 as a boundary, and has a region of a zigzag tip 118 far from the adjacent conductive magnetic body 140. The first magnetization direction 114 is parallel to the direction from the tip of the conductive magnetic body 110 to one end. The second magnetization direction 116 is perpendicular to the direction from the tip of the conductive magnetic body 110 to the other end.

The conductive magnetic body 140 is made of, for example, nickel or a Ni-Fe alloy containing 40 wt % or more of nickel, and the zigzag shape of the wire or thin film is combined in a pair with the zigzag shape of the conductive magnetic body 110. The conductive magnetic body 140 has a zigzag tip 142 on the side close to the adjacent conductive magnetic body 110, a first magnetization direction 144 and a second magnetization direction 146 with the vicinity of the tip 142 as a boundary, and has a region of a zigzag tip 148 on the side farther from the adjacent conductive magnetic body 110. The first magnetization direction 144 is parallel to the direction from the tip of the conductive magnetic body 140 to one end. The second magnetization direction 146 is perpendicular to the direction from the tip of the conductive magnetic body 140 to the other end.

The current application means 120 is a DC power supply device that supplies a current to the conductive magnetic bodies 110, 140 so that a current Jc flows in the flow direction shown in the figure. The wiring 122 connects the conductive magnetic bodies 110, 140, which are unit elements, in series, and is made of a conductive wire such as copper, aluminum, silver, etc. It is also possible to use the same material for the wiring 122 as the conductive magnetic bodies 110, 140, which makes it possible to construct a thermopile using only one type of material.
The heat generating/absorbing region 130 is a structure in which the heat generating/absorbing region is disposed at two or more discrete locations disposed substantially linearly, and is an accumulation of the conductive magnetic bodies 110, 140. Here, "disposed substantially linearly" means that, as shown in Fig. 12, for example, the distance d between the heat generating/absorbing region and the opposing heat generating/absorbing region in the conductive magnetic body of the adjacent unit element is, for example, about half the distance D between the heat generating/absorbing region and the adjacent heat generating/absorbing region in the conductive magnetic body of the same unit element, and therefore the thermal effect of the heat generating/absorbing region of the conductive magnetic body of the same unit element on the heat generating/absorbing region of the conductive magnetic body of the adjacent unit element can be ignored, and the cooling/heating capacity can be efficiently improved in the center of the thermopile structure.

In a device configured in this manner, the conductive magnetic bodies 110, 140 are bent in a zigzag shape, and the heat generating/absorbing regions 130 are arranged in two or more discrete locations that are substantially arranged in a straight line, resulting in heat generating/absorbing regions arranged in a straight line. For example, as shown in FIG. 12, if each conductive magnetic body 110, 140 has five bends, and the amount of heat generated/absorbed per bend is Q, the total amount of heat generated/absorbed along the center of the thermopile structure is |5Q|, which is proportional to the number of bends.

Note that, although the embodiments of the present invention are shown in Figures 1 to 4, 11, and 12, the present invention is not limited to these, and various embodiments are conceivable within a range that would be obvious to a person skilled in the art, and such obvious ranges are also included in the scope of the present invention.

As explained in detail above, according to the present invention, a thermoelectric cooling element/temperature control element can be constructed using a single magnetic material without the joining of different materials, as a new thermal control function brought about by the anisotropic magnetic Peltier effect. Unlike conventional Peltier elements that are constructed using the joining of different materials, it is possible to reconfigure the thermoelectric conversion characteristics by changing the shape and magnetization distribution of the magnetic material, and to modulate the temperature of any desired location by locally magnetizing it.
The anisotropic magnetic Peltier effect is a new thermal management principle suitable for electronics and spintronics devices, and is expected to lead to smaller, lower-cost, and more versatile Peltier elements. By utilizing the above properties, it will be possible to build temperature control devices that could not be realized with conventional elements, such as embedding Peltier elements inside integrated circuits and using the wiring itself for electronic cooling.

10, 40, 50, 60, 110, 140 Conductive magnetic body 12, 42, 52, 62, 112, 142 Tip (for forming heat generating/heat absorbing area)
14, 114, 144 First magnetization direction 16, 116, 146 Second magnetization direction 20, 120 Current application means (battery)
22, 122 Wiring 24, 124 Current flow direction 30, 130 Heat generation/absorption area 32, 132 Heat flow direction in heat generation 34, 134 Heat flow direction in heat absorption 44, 54, 64 First ferromagnetic branch 46, 56, 66 Second ferromagnetic branch 70 Sample (element having anisotropic magnetic Peltier effect)
80 Infrared camera 90 Source meter 100 Calculation and control system Jc DC current M Magnetization

Claims (12)

A plurality of conductive magnetic bodies each having a conductive magnetic body as a unit element, the conductive magnetic body being made of a single material and capable of generating a temperature change due to anisotropic magnetic Peltier effect.
a current applying means provided so as to be able to apply a current to each of the plurality of conductive magnetic bodies;
The boundary between regions where the relative angles of magnetization and current are different is set as a heat generation/absorption region, and the heat generation/absorption region in the conductive magnetic body of the unit element is arranged in two or more discrete locations linearly arranged in a region within a plane formed by the conductive magnetic body, and the plurality of conductive magnetic bodies are integrated,
the magnetization direction of the conductive magnetic body of the unit element is composed of a first magnetization region having a magnetization direction substantially parallel to an axial direction of the conductive magnetic body, and a second magnetization region having a magnetization direction in a direction inclined obliquely in a plane with respect to the first magnetization region or a direction perpendicular to the first magnetization region, with the heat generation/absorption region as a boundary;
A thermopile-type temperature control element, characterized in that the heat generating and heat absorbing regions of the plurality of conductive magnetic bodies form a cross-type thermopile, a five-branch type thermopile, or a six-branch type thermopile. A plurality of conductive magnetic bodies each having a conductive magnetic body as a unit element, the conductive magnetic body being made of a single material and capable of generating a temperature change due to anisotropic magnetic Peltier effect.
a current applying means provided so as to be able to apply a current to each of the plurality of conductive magnetic bodies;
The boundary between regions where the relative angles of magnetization and current are different is set as a heat generation/absorption region, and the heat generation/absorption regions in the conductive magnetic body of the unit element are arranged in two or more discrete locations arranged linearly in a region perpendicular to a surface formed by the conductive magnetic body, and the plurality of conductive magnetic bodies are integrated,
the magnetization direction of the conductive magnetic body of the unit element is composed of a first magnetization region having a magnetization direction substantially parallel to an axial direction of the conductive magnetic body, and a second magnetization region having a magnetization direction in a direction inclined obliquely out of plane or perpendicular to the first magnetization region, with the heat generation/absorption region as a boundary;
A thermopile-type temperature control element, characterized in that the heat generating and heat absorbing regions of the plurality of conductive magnetic bodies form a cross-type thermopile, a five-branch type thermopile, or a six-branch type thermopile. A plurality of conductive magnetic bodies each having a conductive magnetic body as a unit element, the conductive magnetic body being made of a single material and capable of generating a temperature change due to anisotropic magnetic Peltier effect.
a current applying means provided so as to be able to apply a current to each of the plurality of conductive magnetic bodies;
The boundary between regions where the relative angles of magnetization and current are different is set as a heat generation/absorption region, and the heat generation/absorption region in the conductive magnetic body of the unit element is arranged in two or more discrete locations linearly arranged in a region within a plane formed by the conductive magnetic body, and the plurality of conductive magnetic bodies are integrated,
the magnetization direction of the conductive magnetic body of the unit element is composed of a first magnetization region having a magnetization direction substantially parallel to an axial direction of the conductive magnetic body, and a second magnetization region having a magnetization direction in a direction inclined obliquely in a plane with respect to the first magnetization region or a direction perpendicular to the first magnetization region, with the heat generation/absorption region as a boundary;
The plurality of conductive magnetic bodies are two zigzag-type thermopiles, one of the conductive magnetic bodies (110) has a region of a zigzag-shaped tip (112) close to the other adjacent conductive magnetic body (140) and a zigzag-shaped tip (118) far from the other adjacent conductive magnetic body (140), and has a first magnetization direction (114) and a second magnetization direction (116) with the vicinity of the tip (112) as a boundary, the first magnetization direction (114) being parallel to the direction from the tip of the one conductive magnetic body (110) to one end, and the second magnetization direction (116) being perpendicular to the direction from the tip of the one conductive magnetic body (110) to the other end,
The conductive magnetic body (140) has a zigzag-shaped tip (142) close to the one of the adjacent conductive magnetic bodies (110), and a first magnetization direction (144) and a second magnetization direction (146) with the tip (142 ) as a boundary, and also has a region of a zigzag-shaped tip ( 148) far from the one of the adjacent conductive magnetic bodies (110), the first magnetization direction (144) being parallel to the direction from the tip of the conductive magnetic body (140) to one end, and the second magnetization direction (146) being perpendicular to the direction from the tip of the conductive magnetic body (140) to the other end,
The direction of the current applied to one of the conductive magnetic bodies (110) by the current application means is opposite to the direction of the current applied to the other conductive magnetic body (140).
A thermopile type temperature control element characterized by: A plurality of conductive magnetic bodies each having a conductive magnetic body as a unit element, the conductive magnetic body being made of a single material and capable of generating a temperature change due to anisotropic magnetic Peltier effect.
a current applying means provided so as to be able to apply a current to each of the plurality of conductive magnetic bodies;
The boundary between regions where the relative angles of magnetization and current are different is set as a heat generation/absorption region, and the heat generation/absorption regions in the conductive magnetic body of the unit element are arranged in two or more discrete locations arranged linearly in a region perpendicular to a surface formed by the conductive magnetic body, and the plurality of conductive magnetic bodies are integrated,
the magnetization direction of the conductive magnetic body of the unit element is composed of a first magnetization region having a magnetization direction substantially parallel to an axial direction of the conductive magnetic body, and a second magnetization region having a magnetization direction in a direction inclined obliquely out of plane or perpendicular to the first magnetization region, with the heat generation/absorption region as a boundary;
The plurality of conductive magnetic bodies are a plurality of zigzag thermopiles, one of the conductive magnetic bodies (110) has a region of a zigzag-shaped tip (112) close to an adjacent conductive magnetic body (140) and a zigzag-shaped tip (118) far from the adjacent conductive magnetic body (140), and has a first magnetization direction (114) and a second magnetization direction (116) with the vicinity of the tip (112) as a boundary, the first magnetization direction (114) being parallel to the direction from the tip of the one conductive magnetic body (110) to one end, and the second magnetization direction (116) being perpendicular to the direction from the tip of the one conductive magnetic body (110) to the other end,
The conductive magnetic body (140) has a zigzag-shaped tip (142) close to the one of the adjacent conductive magnetic bodies (110), and a first magnetization direction (144) and a second magnetization direction (146) with the tip (142 ) as a boundary, and also has a region of a zigzag-shaped tip ( 148) far from the one of the adjacent conductive magnetic bodies (110), the first magnetization direction (144) being parallel to the direction from the tip of the conductive magnetic body (140) to one end, and the second magnetization direction (146) being perpendicular to the direction from the tip of the conductive magnetic body (140) to the other end,
The direction of the current applied to one of the conductive magnetic bodies (110) by the current application means is opposite to the direction of the current applied to the other conductive magnetic body (140).
A thermopile type temperature control element characterized by: The thermopile-type temperature control element according to any one of claims 1 to 4, characterized in that the conductive magnetic body is made of a ferromagnetic body, a ferrimagnetic body, or an antiferromagnetic body. The thermopile-type temperature control element according to any one of claims 1 to 4, characterized in that the conductive magnetic body is made of nickel or an alloy containing 40 wt% or more of nickel. The thermopile-type temperature control element according to any one of claims 1 to 4, characterized in that the conductive magnetic body is made of nickel or a Ni-Fe alloy containing 40 wt% or more of nickel. An electronic device using a thermopile-type temperature control element according to any one of claims 1 to 7. The thermopile-type temperature control element according to claim 1 or 2, characterized in that in the cross-shaped thermopile, the current applied to the first conductive magnetic body by the current application means is parallel to the direction of the current applied to the second conductive magnetic body adjacent to the first conductive magnetic body. In the five-branch thermopile, the current applied to the first conductive magnetic body by the current application means is in a direction opposite to the direction of the current applied to the second conductive magnetic body adjacent to the first conductive magnetic body,
A thermopile-type temperature control element as described in claim 1 or 2, characterized in that the magnetization direction of the first magnetization region is opposite to the direction of the current applied to the first conductive magnetic body, and the magnetization direction of the second magnetization region has a magnetization direction obliquely inclined or perpendicular to the current applied to the second conductive magnetic body. In the six-branch thermopile, the current applied to the first conductive magnetic body by the current application means is in a direction opposite to the direction of the current applied to the second conductive magnetic body adjacent to the first conductive magnetic body,
A thermopile-type temperature control element as described in claim 1 or 2, characterized in that the magnetization direction of the first magnetization region is opposite to the direction of the current applied to the first conductive magnetic body, and the magnetization direction of the second magnetization region has a magnetization direction obliquely inclined or perpendicular to the current applied to the second conductive magnetic body. The thermopile-type temperature control element according to claim 1 or 2, characterized in that in the six-branch thermopile, the current applied to the first conductive magnetic body by the current application means is in the opposite direction to the current applied to the second conductive magnetic body adjacent to the first conductive magnetic body, and the magnetization direction of the first magnetized region is the same as the magnetization direction of the second magnetized region.