Proceedings Article | 18 September 2018
KEYWORDS: Silicon carbide, Magnetism, Lithium, Antimony, System on a chip, Quantum wells, Glasses
Due to their large bulk band gap, bismuthene, Sb and As on SiC offer intriguing new opportunities for room-temperature quantum spin Hall (QSH) applications. Although edge states have been observed in the local density of states (LDOS) of bismuthene/SiC [1], there has been no experimental evidence until now that they are spin-polarized and topologically protected. We predict experimentally testable fingerprints of these properties originating from magnetic fields, such as changes in the LDOS and in ballistic magnetotransport [2]. We show that the edge termination, zigzag versus armchair, and large Rashba SOC result in fundamental differences of the helical edge states and their protection in bismuthene/SiC compared to those in the better studied HgTe quantum wells [3,4]. In particular, for armchair edges we find a distinctive behavior for out-of-plane fields (gap of a few meV between the QSH states) and fields along the edge direction (no gap). While we focus on bismuthene/SiC, our main findings are also applicable to other honeycomb-lattice-based QSH systems, revealing an unexpected robustness of the QSH states in these systems against magnetic fields due to the interplay between topology and geometry.
[1] F. Reis, G. Li, L. Dudy, M. Bauernfeind, S. Glass, W. Hanke, R. Thomale, J. Schäfer, R. Claessen, Science 357, 287 (2017)
[2] F. Dominguez, B. Scharf, G. Li, J. Schäfer, R. Claessen, W. Hanke, R. Thomale, E. M. Hankiewicz, preprint
[3] G. Tkachov, E. M. Hankiewicz, Phys. Rev. Lett. 104, 166803 (2010)
[4] B. Scharf, A. Matos-Abiague, J. Fabian, Phys. Rev. B 86, 075418 (2012); B. Scharf, A. Matos-Abiague, I. Zutic, J. Fabian, Phys. Rev. B 91, 235433 (2015)
