Novel electronic structure stimulated in surface triangular lattice of strongly correlated topological materials

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K03859
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
• Research Institution: National Institutes for Quantum Science and Technology (2021-2022); Osaka University (2020)
• Principal Investigator: Ohtsubo Yoshiyuki 国立研究開発法人量子科学技術研究開発機構, 次世代放射光施設整備開発センター, 主任研究員 (70735589)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: トポロジカル近藤絶縁体

Outline of Final Research Achievements

Topological insulators hosting low-dimensional electronic states at the edge of the crystals are gathering broad attention in this decade. Among them, topological Kondo insulators derived from strong electron correlation are expected to exhibit various unconventional electronic phenomena, such as complex energy eigenvalues in a triangular lattice.
In this study, some new clean surfaces of samarium hexaboride (SmB6), one of a known topological Kondo insulator, are obtained by a new cleaning technique developed by us. On the surface triangular lattice of SmB6, temperature-driven evolution of the topological electronic states at the triple degenerate points in the surface Brillouin zone is traced. Moreover, we also discovered a new topological surface states exhibiting different symmetry from the 3D states in the crystal on the vicinal surface of SmB6.

Free Research Field

表面物理

Academic Significance and Societal Importance of the Research Achievements

本研究により、これまで作製が困難であったトポロジカル近藤絶縁体単結晶の清浄表面試料を得る方法がサマリウム六硼化物については確立できた。これまで理論的な予測が先行して十分に実験的面からの調査が行えていなかったトポロジカル電子状態と電子相関の協奏効果について、試料準備という実験研究の最初のハードルを大きく引き下げた意義は大きい。
得られた複数の清浄表面試料において観測したトポロジカル表面電子状態においては、三角格子系の温度変化や微傾斜表面の異方的トポロジカル電子状態など、これまでは試料の制限により得られなかった興味深い電子状態の存在が明らかになった。