Proximity enhanced quantum spin Hall state in graphene

Kou, Liangzhi, Hu, Feiming, Yan, Binghai, Wehling, Tim, Felser, Claudia, Frauenheim, Thomas, & Chen, Changfeng (2015) Proximity enhanced quantum spin Hall state in graphene. Carbon, 87(C), pp. 418-423.

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Abstract

Graphene is the first model system of two-dimensional topological insulator (TI), also known as quantum spin Hall (QSH) insulator. The QSH effect in graphene, however, has eluded direct experimental detection because of its extremely small energy gap due to the weak spin–orbit coupling. Here we predict by ab initio calculations a giant (three orders of magnitude) proximity induced enhancement of the TI energy gap in the graphene layer that is sandwiched between thin slabs of Sb2Te3 (or MoTe2). This gap (1.5 meV) is accessible by existing experimental techniques, and it can be further enhanced by tuning the interlayer distance via compression. We reveal by a tight-binding study that the QSH state in graphene is driven by the Kane–Mele interaction in competition with Kekulé deformation and symmetry breaking. The present work identifies a new family of graphene-based TIs with an observable and controllable bulk energy gap in the graphene layer, thus opening a new avenue for direct verification and exploration of the long-sought QSH effect in graphene. © 2015 Elsevier Ltd. All rights reserved.

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ID Code: 98206
Item Type: Journal Article
Refereed: Yes
DOI: 10.1016/j.carbon.2015.02.057
ISSN: 0008-6223
Divisions: Current > Schools > School of Chemistry, Physics & Mechanical Engineering
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2015 Elsevier Ltd.
Deposited On: 25 Aug 2016 03:01
Last Modified: 26 Aug 2016 02:01

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