The National Institute for Materials Science (NIMS) recently made an important breakthrough in the field of thermoelectrics and spintronics. The institute successfully observed the “anisotropic magneto-Thomson effect,” which reveals the changes in heat absorption/release in magnetic materials caused by the magnetization direction. This groundbreaking research opens up possibilities for advancements in basic physics, materials science, and the development of new functionalities that can control thermal energy with magnetism. The findings of this study were published in the renowned journal Physical Review Letters.
The Thomson effect, along with the Seebeck and Peltier effects, is a fundamental thermoelectric phenomenon responsible for driving thermoelectric conversion technologies. While the influence of magnetism on the Seebeck and Peltier effects has been extensively studied, the impact of magnetic fields and magnetism on the Thomson effect has remained elusive. This knowledge gap exists because the Thomson effect is generally minimal, and reliable measurement and quantitative estimation methods have not been fully established.
Addressing the limitations in previous research, NIMS reported an experimental result in 2020 demonstrating the magneto-Thomson effect in nonmagnetic conductors. Building on this prior work, the researchers at NIMS successfully observed the anisotropic magneto-Thomson effect in magnetic materials through more precise thermal measurements.
The anisotropic magneto-Thomson effect observed in magnetic materials differs from the conventional magneto-Thomson effect observed in nonmagnetic materials. This represents the first direct observation of this previously unexplored phenomenon. The researchers employed a specialized thermal measurement technique called lock-in thermography to precisely measure the temperature distribution generated in a ferromagnetic alloy Ni95Pt5 when a charge current is applied along with a temperature difference. By carefully manipulating the magnetization direction, they were able to determine how the Thomson effect changes accordingly.
The results of their experiments revealed that the heat absorption and release in the Ni95Pt5 alloy are more significant when the temperature gradient and charge current are parallel to the magnetization, as opposed to when they are perpendicular to it. These findings align with expectations based on measurements of the Seebeck and Peltier effects in magnetic materials. The study not only clarifies the fundamental properties of the anisotropic magneto-Thomson effect but also establishes techniques for its quantitative measurement.
Following this groundbreaking research, the NIMS team plans to continue exploring the unique physics, materials, and functionalities of the anisotropic magneto-Thomson effect. Their goal is to investigate the new physics resulting from the intricate interaction of heat, electricity, and magnetism. Additionally, they aim to develop applications in thermal management technologies that contribute to the improved efficiency and energy conservation of electronic devices.
The success of this project was made possible through the collaborative efforts of Rajkumar Modak (Special Researcher, Research Center for Magnetic and Spintronic Materials CMSM), Takamasa Hirai (Researcher, CMSM, NIMS), Seiji Mitani (Director, CMSM, NIMS), and Ken-ichi Uchida (Distinguished Group Leader, CMSM, NIMS). The National Institute for Materials Science (NIMS) provided the support and resources necessary for this breakthrough study.
The discovery and direct observation of the anisotropic magneto-Thomson effect in magnetic materials marks a significant milestone in the fields of thermoelectrics and spintronics. By shedding light on the interaction of heat, electricity, and magnetism, this research paves the way for further advancements in fundamental physics and materials science. Moreover, the newfound understanding of the anisotropic magneto-Thomson effect offers new opportunities to develop innovative thermal management technologies, ultimately enhancing the efficiency and energy conservation of electronic devices.