Berlin 2024 – scientific programme
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O: Fachverband Oberflächenphysik
O 40: Poster: Topological Materials
O 40.5: Poster
Tuesday, March 19, 2024, 18:00–20:00, Poster D
A new Bi4Br4 surface structure — •Jonathan K. Hofmann1,2, Hoyeon Jeon3, Saban M. Hus3, An-Ping Li3, Mingqian Zheng4, Jin-Jian Zhou5, Zhiwei Wang4, Yugui Yao4, F. Stefan Tautz1,2, Bert Voigtländer1,2, and Felix Lüpke1 — 1Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, Germany — 2Lehrstuhl für Experimentalphysik IV A, RWTH Aachen University, Germany — 3Center for Nanophase Materials Science, Oak Ridge National Laboratory, Tennesse, USA — 4Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, China — 5Institute of Physics, Chinese Academy of Sciences and Beijing National Laboratory for Condensed Matter Physics, China
Bi4Br4 is a higher-order topological insulator with a quasi-one dimensional crystal structure [1]. We present a new Bi4Br4(001) surface structure analysed with Scanning Tunneling Microscopy/Spectroscopy (STS/STS) at 5 K. STM topography shows an oblique surface structure with characteristic parallel chains shifted by ∼ b/3 with respect to each other, as opposed to the shift of b/2 on α-Bi4Br4(001) [1]. We also observe AB-layer stacking, similar to α-Bi4Br4 [1]. STS reveals the presence of metallic edge states at surface steps, indicating that this new Bi4Br4 structure is also a topological insulator. We propose a crystallographic model for this surface and support our results by density-functional theory calculations.
[1] Shumiya, N.; Hossain, M. S.; Yin, J.-X.; Wang, Z.; Litskevich, M.; Yoon, C.; et al., Nat. Mater. 2022, 21, 1111*1115.