Ultrasound measurements under megagauss fields

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K14403
• 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: Nomura Toshihiro 東京大学, 物性研究所, 助教 (20845987)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 超強磁場 / 超音波 / 酸素 / 非相反 / 量子スピン

Outline of Final Research Achievements

A new method for measuring ultrasonic sound velocity of materials has been successfully developed in combination with the single-turn coil method, a destructive magnetic field generation technique. By applying the developed method to liquid oxygen, quantum spin systems, and heavy fermion systems, we succeeded in obtaining information on the change of elastic constants of materials in the ultrahigh magnetic field-induced phase transitions. In particular, for liquid oxygen, we obtained results suggesting a precursor of the liquid-liquid phase transition induced by a magnetic field. In addition, a giant elastic anomaly in the 1/2 plateau phase was observed in the two-dimensional quantum spin system SrCu2(BO3)2. The developed measurement technique is expected to be a powerful tool to explore ultrahigh magnetic field physics in the future.

Free Research Field

固体物理

Academic Significance and Societal Importance of the Research Achievements

これまで磁場中物性に関する複数の研究がノーベル賞の対象になっていることからわかるように、強磁場下における物質の性質は多彩かつ複雑であり、未だに固体物理のフロンティアにある。超強磁場下における物性測定には多くの制限があり、これまで格子物性に関する情報はほとんど報告例が無かった。本研究では新たに音速（弾性定数）に関する情報を得る計測手法を開発し、物性測定に応用した。本研究で開発した手法は他の物質群にも適用可能であり、超強磁場下での新たな物性を探索する上で強力な手法となる。