Study on the structure and magnetism of crystals composed of spin icosahedra

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H04018
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: Tokyo University of Science
• Principal Investigator: Tamura Ryuji 東京理科大学, 基礎工学部材料工学科, 教授 (50307708)
• Research Collaborator: Gomez Cesar Pay ; Sato Taku J ; Cao Huibo ; Hiroto Takanobu
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 正20面体クラスター / 近似結晶 / 準結晶 / 磁性

Outline of Final Research Achievements

This study was conducted to elucidate the properties of ferromagnetic spin icosahedron in crystals and also to establish the method to controll the magnetism of spin icosahedron crystals. There are three main research results, and firstly, single crystal structure analyses of the Au-Al-(Gd,Tb) spin icosahedron crystals were conducted, and their structures were determined. Second, powder neutron diffraction experiments of the Au-Al-Tb spin icosahedron crystal were conducted, and their magnetic structures were determined. Thirdly, spin icosahedron crystals were prepared in many alloy systems, and it is found that the magnetic ground state can be well tuned only by the number of average valence electrons, and the existence range of spin glasses, ferromagnetism, antiferromagnetic phases,was elucidated. To summarize, the method of controlling the magnetism of spin icosahedron crystals has been well established by this study.

Free Research Field

金属物性

Academic Significance and Societal Importance of the Research Achievements

本研究により、固体中の正20面体が精緻な磁性物理学の対象となった。とりわけ、５つしかないプラトンの正凸多面体のうちの２つの多面体（正12面体、正20面体）を構造単位に有する夥しい結晶群の磁性の理解への第一歩と見なすことができる。また、本研究は、“クラスター磁石”という学問領域が物理学・材料科学において創出されるための第一歩とも見なすことができる。