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Observation of Anisotropic Magneto-Peltier Effect: Temperature of Magnetic Materials Can be Manipulated through Simple Redirection of Charge Current

Observation of Anisotropic Magneto-Peltier Effect: Temperature of Magnetic Materials Can be Manipulated through Simple Redirection of Charge Current

—Novel Heating/Cooling Function Demonstrated Using a Single Magnetic Material without Junction Structure—

For the first time in the world, NIMS and Tohoku University jointly observed an anisotropic magneto-Peltier effect—a thermoelectric conversion phenomenon in which simple redirection of the flow of a charge current in a magnetic material induces heating and cooling.

Abstract

1. For the first time in the world, NIMS and Tohoku University jointly observed an anisotropic magneto-Peltier effect—a thermoelectric conversion phenomenon in which simple redirection of the flow of a charge current in a magnetic material induces heating and cooling. Thermoelectric heating and cooling are conventionally achieved by applying a voltage to a junction between two dissimilar electrical conductors. In this research, we demonstrated a novel thermal control function using a single magnetic material without relying on a junction structure. Although the anisotropic magneto-Peltier effect is a fundamental thermoelectric conversion phenomenon, it was observed for the first time in this study. We hope that this report will stimulate further advances in basic and applied research on thermoelectric conversion.
2. Conversion between charge and heat currents can be achieved in metals and semiconductors by means of the thermoelectric effect. A well-known example of this is the Peltier effect, whereby a conductor can be heated or cooled by applying a charge current. Although the Peltier effect was discovered almost 200 years ago, global research activities on this subject remain active today in an effort to increase the thermoelectric conversion efficiency in electronic devices and apply this phenomenon to a wider range of technologies (e.g., development of more energy-efficient computers).
3. The NIMS-led research team used a thermal measurement technique called lock-in thermography to make detailed measurements of temperature changes in a magnetic material while a charge current was applied. As a result, we observed changes in the Peltier coefficient in relation to the angle between the direction of the charge current and the direction of the magnetization in the magnetic material. It has been previously observed that the Seebeck effect—a phenomenon in which a temperature difference between a conductor produces a charge current—changes in relation to the direction of magnetization; this is called the anisotropic magneto-Seebeck effect. However, the anisotropic magneto-Peltier effect, which is the reciprocal of the anisotropic magneto Seebeck effect, had not been observed before this research.
4. Application of the anisotropic magneto-Peltier effect may enable thermoelectric temperature control of a magnetic material by simply redirecting a charge current in the material and creating an uneven magnetization distribution within it, rather than forming a junction between two dissimilar electrical conductors. In future studies, we will attempt to identify/develop magnetic materials that exhibit large anisotropic magneto-Peltier effects and apply them to the development of thermal management technologies that make electronic devices energy-efficient.
5. This research project was carried out by Ken-ichi Uchida (Group Leader, Spin Caloritronics Group, Research Center for Magnetic and Spintronic Materials, NIMS), Ryo Iguchi (Researcher, Spin Caloritronics Group, Research Center for Magnetic and Spintronic Materials, NIMS), Shunsuke Daimon (Graduate Student, Institute for Materials Research and Advanced Institute for Materials Research, Tohoku University; currently Assistant Professor of The University of Tokyo) and Eiji Saitoh (Professor, Institute for Materials Research and Advanced Institute for Materials Research, Tohoku University; currently Professor of the University of Tokyo).
   This project was supported mainly by the JST Strategic Basic Research Program CREST (JPMJCR17I1) and the JSPS Grant-in-Aid for Scientific Research (A) (JP15H02012).
6. This research was published in the online version of the British scientific journal Nature at 12:00 am on May 22, 2018, Japan Time (4:00 pm on May 21, GMT).

Figure 1 to be used in the press release. Observation of anisotropic magneto-Peltier effects

電流:           Charge current
磁化:           Magnetization
磁性体:       Magnetic material
発熱:           Releasing heat
吸熱:           Absorbing heat
 

定常熱画像:                                   Steady-state thermal image
ロックイン熱画像:                            Lock-in thermal images
ロックイン振幅 (mK):                   Lock-in amplitude (mK)
ロックイン位相 (deg):                     Lock-in phase (deg)

Publication Details

Title: “Observation of anisotropic magneto-Peltier effect in nickel,”
Authors: Ken-ichi Uchida, Shunsuke Daimon, Ryo Iguchi & Eiji Saitoh;
Journal: Nature (2018),
DOI: 10.1038/s41586-018-0143-x

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