Graphene-based topological insulator with an intrinsic bulk band gap above room temperature

Kou, Liangzhi, Yan, Binghai, Hu, Feiming, Wu, Shu-Chun, Wehling, Tim O., Felser, Claudia, Chen, Changfeng, & Frauenheim, Thomas (2013) Graphene-based topological insulator with an intrinsic bulk band gap above room temperature. Nano Letters, 13(12), pp. 6251-6255.

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Abstract

Topological insulators (TIs) represent a new quantum state of matter characterized by robust gapless states inside the insulating bulk gap. The metallic edge states of a two-dimensional (2D) TI, known as the quantum spin Hall (QSH) effect, are immune to backscattering and carry fully spin-polarized dissipationless currents. However, existing 2D TIs realized in HgTe and InAs/GaSb suffer from small bulk gaps (<10 meV) well below room temperature, thus limiting their application in electronic and spintronic devices. Here, we report a new 2D TI comprising a graphene layer sandwiched between two Bi2Se3 slabs that exhibits a large intrinsic bulk band gap of 30-50 meV, making it viable for room-temperature applications. Distinct from previous strategies for enhancing the intrinsic spin-orbit coupling effect of the graphene lattice, the present graphene-based TI operates on a new mechanism of strong inversion between graphene Dirac bands and Bi2Se3 conduction bands. Strain engineering leads to effective control and substantial enhancement of the bulk gap. Recently reported synthesis of smooth graphene/Bi2Se3 interfaces demonstrates the feasibility of experimental realization of this new 2D TI structure, which holds great promise for nanoscale device applications.

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45 citations in Web of Science®

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ID Code: 98215
Item Type: Journal Article
Refereed: Yes
Keywords: band inversion, graphene, large bandgap, quantum well, strain engineering, Topological insulator
DOI: 10.1021/nl4037214
ISSN: 1530-6992
Divisions: Current > QUT Faculties and Divisions > Science & Engineering Faculty
Deposited On: 31 Aug 2016 03:57
Last Modified: 01 Sep 2016 22:48

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