Dresden 2026 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 63: Topology and symmetry protected materials & Topological insulators (joint session O/HL/TT)
O 63.5: Vortrag
Mittwoch, 11. März 2026, 16:00–16:15, HSZ/0401
Topology and Real-Space Obstruction: The Phase Diagram of the Triangular p-Orbital Lattice — •Jonas Erhardt1,2, Sven Schemmelmann3, Fabian Schöttke3, Jörg Schäfer1,2, Giorgio Sangiovanni2,4, Markus Donath3, and Ralph Claessen1,2 — 1Physikalisches Institut, Universität Würzburg — 2Würzburg-Dresden Cluster of Excellence ctd.qmat — 3Physikalisches Institut, Universität Münster — 4Institut für Theoretische Physik und Astrophysik, Universität Würzburg
Triangular p-orbital monolayers (MLs) host a rich topological phase diagram governed by the competition between spin-orbit coupling (SOC) and substrate-induced inversion-symmetry breaking (ISB). The SOC-dominated quantum spin Hall insulator (QSHI) phase arises from a band inversion in the p± manifold and was first realized in indenene, a triangular ML of In atoms on SiC [1]. Real-space interference shifts the associated Wannier centers away from the atoms to interstitial sites A/B, which for the QSHI phase produces an alternating ABAB energy sequence in the charge localization, as demonstrated by scanning tunneling microscopy (STM) [1]. Using the same STM approach, we identify the complementary ISB-dominated regime in a Tl ML on Si(111), where strong adsorption-induced ISB exceeds Tl’s SOC. The charge likewise shifts off the atoms but evidences a non-alternating AABB sequence, characterizing Tl/Si(111) as a trivial obstructed atomic insulator. These results complete the experimental validation of the topological phase diagram for triangular p-orbital MLs.
[1] Nat. Commun. 12, 5396 (2021).
Keywords: Topology; QSHI; Obstructed Atomic Insulator