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O: Fachverband Oberflächenphysik
O 10: Poster Session I: Topological insulators
O 10.2: Poster
Monday, March 1, 2021, 10:30–12:30, P
Dirac Fermions in a Two-Dimensional Triangular Indium Layer on SiC(0001) — •Maximilian Bauernfeind1,3, Jonas Erhardt1,3, Philipp Eck2,3, Jörg Schäfer1,3, Simon Moser1,3, Domenico Di Sante2,3, Ralph Claessen1,3, and Giorgio Sangiovanni2,3 — 1Physikalisches Institut, Universität Würzburg, D-97074 Würzburg, Germany — 2Institut für Theoretische Physik und Astrophysik, Universität Würzburg, D-97074 Würzburg, Germany — 3Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074 Würzburg, Germany
The Kane-Mele model provides an intuitive strategy to realize nontrivial topology in two-dimensional honeycomb lattices. Graphene, the most prominent representative of this class, lacks spin-orbit coupling (SOC), which prevents the formation of a sizeable bulk band gap and the utilization of the topological phase at reasonable temperatures. By enriching the orbital subspace and concomitantly switching to a triangular lattice, new possibilities arise. Here, we demonstrate by angle-resolved photoelectron spectroscopy that a triangular indium lattice grown on SiC(0001) - indenene - hosts massive, i.e., gapped Dirac Fermions at the K-point. The opening of this topologically non-trivial gap of approx. 100 meV relies on the strong local SOC. The in-plane inversion symmetry breaking induced by the substrate counteracts the topology but produces on the other hand a distinctive charge localization that directly reflects the non-trivial topological character of indenene, which allowed us to identify this new quantum spin Hall insulator by scanning tunneling microscopy.