Quantum Spin Hall Effect in Silicene and Two-Dimensional Germanium

Cheng-Cheng Liu, Wanxiang Feng, and Yugui Yao
Phys. Rev. Lett. 107, 076802 – Published 9 August 2011

Abstract

We investigate the spin-orbit opened energy gap and the band topology in recently synthesized silicene as well as two-dimensional low-buckled honeycomb structures of germanium using first-principles calculations. We demonstrate that silicene with topologically nontrivial electronic structures can realize the quantum spin Hall effect (QSHE) by exploiting adiabatic continuity and the direct calculation of the Z2 topological invariant. We predict that the QSHE can be observed in an experimentally accessible low temperature regime in silicene with the spin-orbit band gap of 1.55 meV, much higher than that of graphene. Furthermore, we find that the gap will increase to 2.9 meV under certain pressure strain. Finally, we also study germanium with a similar low-buckled stable structure, and predict that spin-orbit coupling opens a band gap of 23.9 meV, much higher than the liquid nitrogen temperature.

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  • Received 18 April 2011

DOI:https://doi.org/10.1103/PhysRevLett.107.076802

© 2011 American Physical Society

Authors & Affiliations

Cheng-Cheng Liu, Wanxiang Feng, and Yugui Yao*

  • Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

  • *To whom correspondence should be addressed. ygyao@aphy.iphy.ac.cn

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Vol. 107, Iss. 7 — 12 August 2011

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