The National Institute for Materials Science (NIMS) has recently made a groundbreaking discovery in the field of thermoelectrics and spintronics. Their research focused on the “anisotropic magneto-Thomson effect,” which refers to the anisotropic change in heat absorption/release proportional to an applied temperature difference and charge current. This phenomenon has long been known as the Thomson effect and is considered one of the fundamental thermoelectric effects in metals and semiconductors, along with the Seebeck and Peltier effects.
While previous studies have explored the influence of magnetism on the Seebeck and Peltier effects, the effect of magnetic fields on the Thomson effect has remained largely unexplored. The Thomson effect is generally small in magnitude, making it challenging to measure accurately and quantitatively. Consequently, researchers have not fully established the measurement and estimation methods for this particular thermoelectric conversion.
In 2020, NIMS published an experimental observation of the magneto-Thomson effect in nonmagnetic conductors, demonstrating a change in the Thomson effect under the influence of a magnetic field. Building upon this previous work, the NIMS research team used lock-in thermography, a precise thermal measurement technique, to examine the anisotropic magneto-Thomson effect in magnetic materials.
The First Direct Observation of Anisotropic Magneto-Thomson Effect
The researchers focused their investigations on a ferromagnetic alloy called Ni95Pt5. By applying a temperature difference and measuring the temperature distribution generated when a charge current passes through the alloy, they were able to observe the anisotropic magneto-Thomson effect directly.
The results revealed that the amount of heat absorption or release in Ni95Pt5 is greater when the temperature gradient and charge current align with the magnetization direction. In other words, the Thomson effect changes depending on the magnetization direction, indicating an anisotropic nature. This discovery is consistent with the behavior observed in measurements of the Seebeck and Peltier effects in magnetic materials.
This research project not only sheds light on the fundamental properties of the anisotropic magneto-Thomson effect but also establishes quantitative measurement techniques. By better understanding how magnetism affects the Thomson effect, researchers can further explore the complex interplay between heat, electricity, and magnetism. This exploration may lead to the discovery of new physics and the development of novel applications for thermal management technologies.
Moving forward, the NIMS research team aims to delve into the physics, materials, and functionalities of the anisotropic magneto-Thomson effect. By exploring the interactions between heat, electricity, and magnetism, they hope to unlock new possibilities for improved efficiency and energy conservation in electronic devices. The insights gained from this research have the potential to revolutionize the field of thermal management technologies.
This remarkable project was made possible thanks to the efforts of Rajkumar Modak, a Special Researcher at the Research Center for Magnetic and Spintronic Materials (CMSM) in NIMS, along with Takamasa Hirai (Researcher at CMSM), Seiji Mitani (Director of CMSM), and Ken-ichi Uchida (Distinguished Group Leader at CMSM). Their dedication and expertise have paved the way for future advancements in materials science and the fusion of thermoelectrics and spintronics. Through their collective efforts, we can anticipate exciting developments in the field of thermal energy control through magnetism.
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