Regensburg 2019 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 12: HL Poster I
HL 12.23: Poster
Montag, 1. April 2019, 17:30–20:00, Poster E
Quantum Spin Hall Insulator Phase in Graphene/Bismuthene Quantum Well Heterostructure — Hamoon Fahrvandi1, •Ebrahim Nadimi1,2, and Michael Schreiber2 — 1Faculty of Electrical Engineering, Center for Computational Micro and Nanoelectronics, K. N. Toosi University of Technology, Tehran, Iran. — 2Institute of Physics, Chemnitz University of Technology, 09107 Chemnitz, Germany.
Quantum spin Hall insulators (QSHI) have attracted much research interest due to their unique electronic properties. Time-reversal-symmetry-protected helical edge states provide dissipationless conductance at the boundaries of these two-dimensional (2D) systems. On the other hand, graphene another prominent 2D material, possesses just an ignorable QSHI phase with a small gap of about 1 meV. This is due to the weak spin-orbit coupling (SOC) in C atoms. In order to combine superior properties of graphene with unique electronic properties of novel QSHI, the idea of increasing SOC in graphene by proximity effect of a strong topological insulator has been proposed. This motivated us to investigate a vertical quantum well heterostructure of bismuthene-graphene-bismuthene (B-G-B) employing first-principles density-functional theory. We found that the proximity-enhanced SOC effect originating from bismuthene, leads to an enhancement in nontrivial topological nature of graphene. A weak van-der-Waals interaction in B-G-B heterostructure protects QSHI states with a sizable nontrivial gap. This structure can be a suitable candidate for realizing room temperature spintronic applications.