Interplay between topology and thermal fluctuation in skyrmion-hosting materials

2021 Fiscal Year Final Research Report

• Project/Area Number: 20K14410
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
• Research Institution: The University of Tokyo
• Principal Investigator: Oike Hiroshi 東京大学, 大学院工学系研究科(工学部), 助教 (70725283)
• Project Period (FY): 2020-04-01 – 2022-03-31
• Keywords: トポロジー / 非平衡 / 磁性 / 準安定 / 熱ゆらぎ / スキルミオン / ゲージ場 / ベリー位相

Outline of Final Research Achievements

The purpose of this project is to search for electromagnetic response derived from interplay between topology and thermal fluctuations. Conduction electrons in skyrmion materials are confined in a topological space that is different from those in vacuum, and consequently behave as if they feel a magnetic field. In the present study, the effect of thermal fluctuations on this emergent magnetic field was examined from both experimental and theoretical aspects. It was found that the strength of the emergent magnetic field weakens with increasing temperature, and suggested that the temperature dependence is due to topology changes caused by thermal fluctuations. These results mean that the effects of thermal fluctuations, which have not been considered much in the study of topological properties, are important for quantitative understanding and designing of them in materials at finite temperatures.

Free Research Field

物性物理学

Academic Significance and Societal Importance of the Research Achievements

本研究の学術的意義は、理想的な系の考察に基づく「トポロジー」という概念と、現実の系に内在する「ゆらぎ」という概念を融合させたことである。このような異なる前提から導かれた概念を融合することは、新たな研究領域の開拓に繋がる可能性を秘めている。また、本研究の社会的意義は、トポロジカルな性質に基づく材料開発の新たな指針を提示したことである。磁気スキルミオン物質中における電子の応答は、熱電変換の新原理としての応用が期待される一方で、低温極限でしか定量的な理解が実現されていなかった。本研究で定量評価が可能な温度域を拡張したことは、高効率な熱電変換材料の設計指針の確立に繋がると考えている。