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TT: Fachverband Tiefe Temperaturen
TT 57: Topology and Symmetry-protected Materials (joint session O/TT)
TT 57.4: Vortrag
Freitag, 21. März 2025, 11:15–11:30, H25
Bismuthene at the Graphene/SiC Interface: A Protected Quantum Spin Hall Insulator — •Niclas Tilgner1, Susanne Wolff1, Serguei Soubatch2, Andres D. P. Unigarro1, Sibylle Gemming1, F. Stefan Tautz2, Christian Kumpf2, Thomas Seyller1, Fabian Göhler1, and Philip Schädlich1 — 1Institute of Physics, Chemnitz University of Technology, Germany — 2Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, Germany
Quantum spin Hall insulators (QSHIs) hold the potential to revolutionize next-generation technologies. Kane and Mele identified 2D honeycomb structures of heavy atoms with strong spin-orbit coupling as promising candidates for these materials. To realize this potential, however, the QSHI must be shielded from environmental influences. Previous research has demonstrated the intercalation of 2D Bi layers beneath graphene on SiC, resulting in the formation of two distinct phases. Among those, the β-phase exhibits a (√3 × √3)R30∘ periodicity relative to the substrate. We identify the Bi adsorption site using x-ray standing wave imaging, a method which deterimes the element specific, 3D atomic distribution with respect to the bulk unit cell. After subsequent hydrogen intercalation, the Bi position changes significantly from hollow to top site adsorption. Further measurements with angle-resolved photoelectron spectroscopy reveal the band structure of the QSHI bismuthene with a pronounced Rashba splitting and slight p-type doping. We propose that the initial β-phase has to be considered as an electronically inactive layer of bismuthene, whose electronic structure can be established by subsequent hydrogen intercalation.
Keywords: topological insulator; quantum spin Hall insulator; bismuthene; graphene; intercalation