External modulation and application of topological states in topological crystal insulators

2020 Fiscal Year Final Research Report

• Project/Area Number: 18H01857
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 29010:Applied physical properties-related
• Research Institution: University of Tsukuba
• Principal Investigator: KURODA Shinji 筑波大学, 数理物質系, 教授 (40221949)
• Co-Investigator(Kenkyū-buntansha): 木村 昭夫 広島大学, 先進理工系科学研究科(理), 教授 (00272534) ; 秋山 了太 東京大学, 大学院理学系研究科(理学部), 助教 (40633962)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: トポロジカル絶縁体

Outline of Final Research Achievements

In this study, we intend to reveal the peculiar physical properties arising from the topological surface states in SnTe and mixed crystals (Pb,Sn)Te, typical materials of topological crystalline insulators, with an emphasis on how external perturbations which break the mirror reflection symmetry of the crystals. We have investigated the unoccupied electronic states by performing time-resolved angle-resolved photoemission spectroscopy measurement on SnTe and (Pb,Sn)Te thin films grown by molecular beam epitaxy and have observed the whole structure of Dirac cones and the Rashba splitting of bulk valence-band. In addition, we have investigated the depth profile of magnetization in heterostructures of SnTe and a ferromagnet by measuring spin-polarized neutron reflectance, revealing magnetization induced at the interface via the topological surface states.

Free Research Field

固体物性

Academic Significance and Societal Importance of the Research Achievements

トポロジカル結晶絶縁体においては、結晶の鏡映対称性によりトポロジカル表面状態が保護されており、鏡映対称性を破る摂動が表面状態にどのような影響を与えるかは興味ある課題である。本研究では、トポロジカル結晶絶縁体の代表物質であるSnTeおよび混晶の(Pb,Sn)Teにおいて非占有側の表面状態の観察および強磁性体との接合界面での磁化誘起の検出という成果を得ており、格子歪および磁化の発現という摂動が表面状態に与える影響を明らかにしたという点で意義ある成果であると言える。