SKM 2023 – scientific programme

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O: Fachverband Oberflächenphysik

O 94: Topology and Symmetry-Protected Materials

O 94.7: Talk

Friday, March 31, 2023, 12:00–12:15, GER 38

Orbital angular momentum in indenene measured by circular dichroism in ARPES — •Jonas Erhardt, Cedric Schmitt, Simon Moser, and Ralph Claessen — Physikalisches Institut and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, Würzburg D- 97074, Germany

Indenene, a monolayer of In atoms arranged in a triangular lattice on SiC(0001), has recently been identified as a quantum spin Hall insulator (QSHI) [1]. Its topological character is encoded in a characteristic energy staggering of its orbital angular momentum (OAM) polarized Dirac states [1]. This makes indenene an ideal test case for recent claims that circular dichroism in angle-resolved photoelectron spectroscopy (CD-ARPES) gives access to local Berry curvature signatures via the OAM [2]. However, a particular challenge of such experiments is the extraction of the intrinsic OAM-related CD signal, requiring its distinction from final state effects and extrinsic contributions induced by experimental geometry.
In this talk, I will present a systematic photon energy dependent CD-ARPES study of indenene’s Dirac states and use simple geometric considerations to disentangle experimental from OAM induced CD. The resulting OAM sequence confirms indenene to be a QSHI and thus establishes a new approach to experimentally identify the topological character of a 2D quantum material directly from its bulk states.
[1] M. Bauernfeind et al., Nat. Commun., 12, 5396 (2021)
[2] M. Schüler et al., Sci. Adv., 6, 2730 (2020)