Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 18: Poster Session: Topological Topics (joint session TT/MA)

TT 18.2: Poster

Montag, 1. April 2019, 15:00–18:30, Poster D

Potassium-Induced n-Doping of the High-Temperature Quantum Spin Hall System Bismuthene on SiC(0001) — •Johannes Weis, André Kowalewski, Felix Reis, Raul Stühler, Felix Spriestersbach, Lenart Dudy, Victor Rogalev, Jörg Schäfer, and Ralph Claessen — Physikalisches Institut und Röntgen Center for Complex Material Systems, Universität Würzburg, D-97074 Würzburg, Germany

Bismuthene, a monolayer of Bi-atoms bonded onto a SiC(0001) substrate in a honeycomb lattice, has recently been experimentally realized [1]. This 2D system has a large band gap of approx. 0.8 eV and is a most promising candidate for the realization of the quantum spin Hall effect at room-temperature. Theoretical tight-binding and DFT calculations consistently predict the existance of helical edge states forming Dirac branches. While Reis et al. [1] showed proof for 1D metallic edge states spanning the 2D bulk band gap by means of STM and STS, up to date a direct experimental observation of the linear electron dispersion has not been reported and ARPES would be highly desirable.

One major obstacle here is the Fermi level being too close to the 2D bulk valence band maximum. Here we present the adsorption of potassium as a tool to shift the Fermi level above the predicted Dirac point in a controlled way. The effect of the dopant has been investigated both on an atomic level by STM and STS and spacially integraged by ARPES.

[1] F. Reis et al., Science 357,287-290 (2017)