Theoretical study towards establishing odd-parity multiple materials science: classification, electromagnetic responses, superconductivity

2022 Fiscal Year Final Research Report

• Project/Area Number: 18H01178
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
• Research Institution: Kyoto University
• Principal Investigator: Yanase Youichi 京都大学, 理学研究科, 教授 (70332575)
• Project Period (FY): 2018-04-01 – 2022-03-31
• Keywords: 奇パリティ多極子 / エキゾチック超伝導 / 非相反応答 / 非線形応答 / スピン軌道相互作用

Outline of Final Research Achievements

With this research project, we have completed a group-theoretical classification of odd-parity multipole orders. We have also identified more than 100 odd-parity magnetic multipole materials and elucidated novel electromagnetic responses such as the magneto-piezoelectric effect. We also formulated the multipole moment in crystals in quantum mechanical theory. As an extension of these studies, we proposed the concept of multipole superconductivity and predicted the phenomenon of ferroelectric superconductivity. Furthermore, we classified the nonlinear optical responses and nonreciprocal transport phenomena in magnetic and superconducting materials, and clarified the close relationship with the symmetry of the order parameter and the quantum geometry of the Bloch wave function.

Free Research Field

物性理論

Academic Significance and Societal Importance of the Research Achievements

本研究により、金属、半導体、絶縁体、さらには磁性体、誘電体、超伝導体を含む多様な物質群を対象とする奇パリティ多極子物質科学が拓かれた。特に、数多くの奇パリティ多極子物質相を分類すると同時に候補物質を同定したことにより、未知の電磁応答が解明された。また、非線形光学や超伝導体の研究に発展したことにより、光物性や超伝導科学との接点が生まれた。これにより分野融合的な研究が今後加速することが期待される。