One-dimensional metallic state of dislocations in topological insulators

2020 Fiscal Year Final Research Report

• Project/Area Number: 18H01692
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 26010:Metallic material properties-related
• Research Institution: The University of Tokyo
• Principal Investigator: Edagawa Keiichi 東京大学, 生産技術研究所, 教授 (20223654)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: トポロジカル絶縁体 / Bi-Sb / 転位 / 電気伝導

Outline of Final Research Achievements

We experimentally investigated the theoretically predicted dislocation conduction in Bi-Sb topological insulator (TI). We plastically deformed the crystals to introduce high-density dislocations with the Burgers vector satisfying the conductivity condition. Then, we cut out microsamples for electrical conductivity measurements. As a result, excess conductivity due to dislocation conduction were observed, which can be attributed to the formation of 1D propagating states along dislocations in the 3D TI.
We also fabricated bulk-insulating Pb-(Bi,Sb)-(Te,Se) TI crystals. By using low temperature scanning tunneling microscopy and spectroscopy, we clarified the electronic structure of the surface states and the scattering mechanism of surface electrons.

Free Research Field

材料強度物性

Academic Significance and Societal Importance of the Research Achievements

本研究は、これまで理論的には予測されるにとどまっていたトポロジカル絶縁体中転位の金属状態について、初めて実験により実証した。この成果は、これまでトポロジカル絶縁体の表面/エッジに限られていた特殊な金属状態の研究対象をバルク内の転位に広げるものであり、そのような金属状態の基礎的物性研究の進展に寄与するものである。
また、Pb-(Bi,Sb)-(Te,Se)系トポロジカル絶縁体のバルク絶縁性向上の成果は、転位伝導だけでなく、従来のトポロジカル絶縁体の表面伝導の研究の進展にも寄与するものである。