Dresden 2026 – scientific programme

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O: Fachverband Oberflächenphysik

O 63: Topology and symmetry protected materials & Topological insulators (joint session O/HL/TT)

O 63.11: Talk

Wednesday, March 11, 2026, 17:30–17:45, HSZ/0401

Defect-induced displacement of topological surface state in magnetic topological insulator MnBi₂Te₄ — •Felix Lüpke^1,2, Marek Kolmer^3,4, Hengxin Tan⁵, Adam Kaminski^3,4, and Binghai Yan^5,6 — ¹Peter Grünberg Institute (PGI-3) and JARA-FIT, Forschungszentrum Jülich, 52425 Jülich, Germany — ²Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany — ³Ames National Laboratory, Ames, Iowa 50011, USA — ⁴Iowa State University, Ames, Iowa 50011, USA — ⁵Weizmann Institute of Science, Rehovot 7610001, Israel — ⁶The Pennsylvania State University, University Park, Pennsylvania 16802, USA

The gapped topological surface states of MnBi₂Te₄ (MBT) are an attractive platform for the realization of quantum anomalous Hall and Axion insulator states. However, experimentally observed surface state gaps fail to meet theoretical predictions, with the exact mechanism behind the gap suppression still being debated. We report on the effect of intrinsic anti-site defects on the MBT surface states, which we study using scanning tunneling microscopy (STM), angle-resolved photoemission (ARPES), and density functional theory (DFT). Our results show that high defect concentrations lead to a displacement of the surface states into the interior of the MBT crystal, consistent with theoretical predicitons [PRL 130, 126702 (2023)].

Keywords: Magnetic topological insulators; Lattice defects; Scanning tunneling microscopy; Angle-resolved photoemission spectroscopy; Density functional theory