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Title: Large quantum-spin-Hall gap in single-layer 1T' WSe 2

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 1T' 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 1T' 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.

Authors:
ORCiD logo [1];  [2];  [3];  [4]; ORCiD logo [5];  [4];  [6];  [7];  [8]
  1. University of Illinois at Urbana-Champaign, Urbana, IL (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. National Taiwan Univ., Taipei (Taiwan)
  3. Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei (Taiwan)
  4. National Tsing Hua University, Hsinchu (Taiwan)
  5. University of Illinois at Urbana-Champaign, Urbana, IL (United States)
  6. National Taiwan Univ., Taipei (Taiwan); Georgia Inst. of Technology, Atlanta, GA (United States)
  7. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  8. University of Illinois at Urbana-Champaign, Urbana, IL (United States); National Taiwan Univ., Taipei (Taiwan)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
OSTI Identifier:
1506388
Grant/Contract Number:  
AC02-05CH11231; FG02-07ER46383
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 9; Journal Issue: 1; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats

Chen, P., Pai, Woei Wu, Chan, Y. -H., Sun, W. -L., Xu, C. -Z., Lin, D. -S., Chou, M. Y., Fedorov, A. -V., and Chiang, T. -C. Large quantum-spin-Hall gap in single-layer 1T' WSe2. United States: N. p., 2018. Web. doi:10.1038/s41467-018-04395-2.
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. Large quantum-spin-Hall gap in single-layer 1T' WSe2. United States. doi:10.1038/s41467-018-04395-2.
Chen, P., Pai, Woei Wu, Chan, Y. -H., Sun, W. -L., Xu, C. -Z., Lin, D. -S., Chou, M. Y., Fedorov, A. -V., and Chiang, T. -C. Mon . "Large quantum-spin-Hall gap in single-layer 1T' WSe2". United States. doi:10.1038/s41467-018-04395-2. https://www.osti.gov/servlets/purl/1506388.
@article{osti_1506388,
title = {Large quantum-spin-Hall gap in single-layer 1T' WSe2},
author = {Chen, P. and Pai, Woei Wu and Chan, Y. -H. and Sun, W. -L. and Xu, C. -Z. and Lin, D. -S. and Chou, M. Y. and Fedorov, A. -V. and Chiang, T. -C.},
abstractNote = {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 WSe2 single layer with the 1T' structure that does not exist in the bulk form of WSe2. Using angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy/spectroscopy (STM/STS), we observe a gap of 129 meV in the 1T' 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.},
doi = {10.1038/s41467-018-04395-2},
journal = {Nature Communications},
issn = {2041-1723},
number = 1,
volume = 9,
place = {United States},
year = {2018},
month = {5}
}

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