Probing broken symmetry by triple-axis controlled magnetization measurements

2020 Fiscal Year Final Research Report

• Project/Area Number: 18H01164
• 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: The University of Tokyo
• Principal Investigator: Sakakibara Toshiro 東京大学, 物性研究所, 教授 (70162287)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 磁性 / 相転移 / 対称性の破れ / 磁化測定

Outline of Final Research Achievements

We have developed a triple-axis-controlled magnetization measurement system as a new means of detecting symmetry breaking associated with phase transitions in solid-state electron systems. This system can measure the magnetization of a sample at low temperatures down to 0.3 K with precisely rotating the magnetic field around a specific crystal axis. Using this apparatus, we have examined the spontaneous symmetry breaking of the threefold valley degeneracy in Bi, which was reported in previous magnetoresistivity measurements at low temperatures in an applied magnetic field. In our magnetization measurements, however, we found no evidence of a threefold symmetry breaking in Bi.

Free Research Field

固体物理学

Academic Significance and Societal Importance of the Research Achievements

相転移における対称性の破れを検出する手段としてX線や中性子による構造解析は強力な実験手段である。しかし、電子系における相転移には、これらの回折実験では検出できない場合が少なくない。ある種の軌道整列やネマチック転移、異方的超伝導転移などがそのような例に含まれる。本課題で開発した回転磁場下の磁化測定装置は，このような対称性の破れを検出する新たな測定手段を提供するもので，相転移現象の解明に広く応用できるものである．