Large quantum-spin-Hall gap in single-layer 1T′ WSe2

Large quantum-spin-Hall gap in single-layer 1T′ WSe2

Abstract Two-dimensional (2D) topological insulators (TIs) are promising platforms for low-dissipation spintronic devices based on the quantum-spin-Hall (QSH) effect, but experimental realization of such systems with a large band gap suitable for room-temperature applications has proven difficult. H...

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Bibliographic Details
Published in:Nature communications 2018-05, Vol.9 (1), p.1-7, Article 2003
Main Authors: Chen, P., Pai, Woei Wu, Chan, Y.-H., Sun, W.-L., Xu, C.-Z., Lin, D.-S., Chou, M. Y., Fedorov, A.-V., Chiang, T.-C.
Format: Article
Language:eng
Subjects:
Band gap
Boundary layers
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
First principles
MATERIALS SCIENCE
Microscopy
Photoelectric emission
Scanning tunneling microscopy
Short term memory
Spectroscopy
Spectrum analysis
Topological insulators
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Summary:Abstract Two-dimensional (2D) topological insulators (TIs) are promising platforms for low-dissipation spintronic devices based on the quantum-spin-Hall (QSH) effect, but experimental realization of such systems with a large band gap suitable for room-temperature applications has proven difficult. Here, we report the successful growth on bilayer graphene of a quasi-freestanding WSe 2 single layer with the 1 T ′ structure that does not exist in the bulk form of WSe 2 . Using angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy/spectroscopy (STM/STS), we observe a gap of 129 meV in the 1 T ′ layer and an in-gap edge state located near the layer boundary. The system′s 2D TI characters are confirmed by first-principles calculations. The observed gap diminishes with doping by Rb adsorption, ultimately leading to an insulator–semimetal transition. The discovery of this large-gap 2D TI with a tunable band gap opens up opportunities for developing advanced nanoscale systems and quantum devices.
ISSN:2041-1723
2041-1723