Atomic scale observations of a strongly correlated topological insulator by spin and orbital resolved STM

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H02595
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 29020:Thin film/surface and interfacial physical properties-related
• Research Institution: Nagoya University (2020-2021); The University of Electro-Communications (2019)
• Principal Investigator: Miyamachi Toshio 名古屋大学, 未来材料・システム研究所, 准教授 (10437361)
• Co-Investigator(Kenkyū-buntansha): 小森 文夫 東京工業大学, 物質理工学院, 研究員 (60170388)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: トポロジカル絶縁体 / 走査トンネル顕微鏡 / 近藤効果 / スピン

Outline of Final Research Achievements

We performed spin and orbital resolved STM measurements for YbB12, which is a promising candidate as a topological Kondo insulator. The purpose of this work was to understand the origin of spin-polarized surface states of YbB12 by STM in terms of electron correlations. We first optimized surface preparation conditions and realized large-area and atomically homogeneous YbB12 surface. Orbital-resolved STM observations on this surface in combination with STM Imaging of quasiparticle interference enable to discuss the roles of s, p, d, f orbitals on the emergence of metallic surface states both from real-space and momentum-space. We further performed spin polarized STM to investigate the spin polarization of YbB12 surface.

Free Research Field

表面科学, ナノ磁性

Academic Significance and Societal Importance of the Research Achievements

本研究によって、トポロジカル近藤絶縁体候補物質YbB12の金属表面状態をSTMによりスピン・電子軌道ごとに分解して評価できることが明らかになった。このことは、強相関電子系特有の新奇なトポロジカル量子現象の発現が期待される系においてSTMが新規機能性の発現機構を理解する上で強力な手法であることを示している。本研究成果によって、強相関トポロジカル絶縁体のみならず、表面数原子層の様々な電子軌道のスピンが物性を担い、かつ将来のデバイス応用が見込まれる系の新しい研究展開が期待できる。