Study on Topological Phase Transition Using Angle-Resolved Photoemission Spectroscopy with Uniaxial Stress Application

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K03433
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 13020:Semiconductors, optical properties of condensed matter and atomic physics-related
• Research Institution: Hiroshima University
• Principal Investigator: Masashi Arita 広島大学, 技術センター, 技術専門職員 (20379910)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 角度分解光電子分光 / 一軸歪印可 / 外場印可 / トポロジカル物質 / CDW

Outline of Final Research Achievements

The aim of this study was to observe changes in the electronic structure of the material by applying uniaxial strain to the crystal lattice and using angle-resolved photoemission spectroscopy (ARPES). For Pb1-xSnxTe, it was difficult to observe topological phase transitions by applying uniaxial strain. Consequently, we developed three uniaxial strain holders for use with ARPES measurement: substrate strain type, piezoelectric device type, and screw type uniaxial strain holders. Using these holders, we successfully observed changes in the electronic structure of the charge density wave material 1T-TaS2 and the topological insulator Bi2Te3 under uniaxial strain.
The developed uniaxial strain sample holders for ARPES measurements can be widely used by collaborative researchers in ARPES apparatus equipped at our undulator beamline. In the environment established through this research project, it has become possible to perform ARPES measurements under various external fields.

Free Research Field

固体物性

Academic Significance and Societal Importance of the Research Achievements

ARPESは、超高真空中で行う表面敏感な測定手法であるため、外場印可下で測定は難易度が高いが、この研究課題を通し放射光ARPES装置において一軸歪印可のARPES測定手法を確立できた。一軸歪印可ARPES測定を用い、CDW物質1T-TaS2のCDW抑制やトポロジカル絶縁体Bi2Te3の歪誘起で新しいトポロジカル表面状態の変化をとらえることができた。
さらに、試料ホルダに電極を装備させたことで、ホルダ上で電気回路を組むことができ、電場や電流、磁場印可測定の可能性を広げ、国内で初めて放射光高分解能ARPESビームラインで、複数の外場印可測定を可能にした。今後、実際のデバイス開発に応用でき得る。