Berlin 2018 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 7: Topological insulators I (joint session HL/TT)

HL 7.9: Vortrag

Montag, 12. März 2018, 11:45–12:00, A 151

Testing Topological Protection of Edge States in Bismuthene on SiC — •Fernando Dominguez1, Benedikt Scharf1, Gang Li2, Werner Hanke3, Ronny Thomale3, and Ewelina Hankiewicz11Institute for Theoretical Physics and Astrophysics, TP4, University of Würzburg, Am Hubland, 97074 Würzburg, Germany — 2School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China — 3Institute for Theoretical Physics and Astrophysics, TP1, University of Würzburg, Am Hubland, 97074 Würzburg, Germany

Due to its large bulk band gap, bismuthene on SiC offers intriguing new opportunities for room-temperature quantum spin Hall (QSH) applications. Although edge states have been observed in the local density of states (LDOS), there has been no experimental evidence until now that they are spin polarized and topologically protected. Here, we predict experimentally testable fingerprints of these properties originating from magnetic fields, such as changes in the LDOS and in ballistic magnetotransport due to a gap of a few meV opened at the crossing point between the QSH states. For armchair edges in particular, we find a distinct difference of behavior under out-of-plane (gap opening between the QSH states) and in-plane (no or tiny gap) fields. This unexpected robustness of armchair QSH edge states against in-plane fields can be understood from an effective low-energy model, where a helicity operator provides an additional protection of the QSH states. While we focus here on bismuthene on SiC, our main findings should also be applicable to other honeycomb-lattice-based QSH systems.

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