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O: Fachverband Oberflächenphysik
O 3: Mini-Symposium: Ultrafast surface dynamics at the space-time limit I
O 3.4: Hauptvortrag
Montag, 1. März 2021, 11:45–12:00, R1
Probing the ultrafast electron dynamics in the quantum spin Hall system Bismuthene with time-resolved ARPES — •Julian Maklar1, Raul Stühler2, Maciej Dendzik1,3, Tommaso Pincelli1, Shuo Dong1, Samuel Beaulieu1, Martin Wolf1, Ralph Ernstorfer1, Ralph Claessen2, and Laurenz Rettig1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, D-14195 Berlin, Germany — 2Physikalisches Institut and Würzburg-Dresden Cluster of Excellence ct.qmat, University of Würzburg, D-97070 Würzburg, Germany — 3Department of Applied Physics, KTH Royal Institute of Technology, Stockholm, Sweden
Quantum spin Hall (QSH) systems are 2D topological insulators with promising device applications due to dissipationless, symmetry-protected spin currents in their edges. A promising high-temperature QSH material is Bismuthene -- a 2D honeycomb lattice of bismuth atoms on a silicon carbide substrate -- which features a wide bulk band gap and conductive 1D edge states located at substrate steps and domain boundaries.
Here, we investigate the electronic structure of Bismuthene upon ultrafast photoexcitation via time- and angle-resolved photoemission spectroscopy (trARPES). We map out the transiently occupied excited states in the conduction band and additionally observe faint spectral weight within the indirect band gap, which we attribute to metallic edge states. In addition, we observe a surprisingly fast recovery of excited carriers to the ground state -- a further hint towards the presence of topological metallic decay channels.