Exploration of New Phenomena Unique to Spin Icosahedra

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01044
• 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: Tokyo University of Science
• Principal Investigator: Tamura Ryuji 東京理科大学, 先進工学部マテリアル創成工学科, 教授 (50307708)
• Co-Investigator(Kenkyū-buntansha): 杉本 貴則 大阪大学, 量子情報・量子生命研究センター, 特任准教授(常勤) (70735662)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 準結晶 / 近似結晶 / 正20面体

Outline of Final Research Achievements

In recent years, there has been significant interest in the unique phenomena of rare-earth spin icosahedra. In this study, we closely investigated the magnetism, particularly the magnetic structure, of rare-earth spin icosahedra in Au-based compounds. In this work, we synthesized a series of Au-Ga-Tb compounds with slightly different Au/Ga ratios, revealing the presence of ferromagnetic, antiferromagnetic, and spin-glass phases, and determined all magnetic structures through neutron diffraction experiments. As a result, we identified the existence of whirling ferromagnetic and antiferromagnetic orders, which directly reflect the symmetry of the icosahedron. On the theoretical side, we simulated the magnetization process and specific heat, which can be compared with experiments, thereby establishing a scholarly foundation for understanding the magnetism of spin icosahedra.

Free Research Field

金属物性

Academic Significance and Societal Importance of the Research Achievements

正20面体は正12面体とともにプラトンの多面体として古くから知られているが、その物性に関する理解は現代に至るまで遅々として進んでいなかった。本研究は、固体中の正20面体の物性（磁性）に関する実験的研究であることに学術的意義があり、本研究により、正20面体上の特異なスピン配列が解明された。また、正20面体上で見い出された非共面磁気構造を用いた新たな物性研究や応用研究が今後立ち上がることが期待される。