Two-Dimensional Topological Insulator State and Topological Phase Transition in Bilayer Graphene

Zhenhua Qiao, Wang-Kong Tse, Hua Jiang, Yugui Yao, and Qian Niu
Phys. Rev. Lett. 107, 256801 – Published 14 December 2011

Abstract

We show that gated bilayer graphene hosts a strong topological insulator (TI) phase in the presence of Rashba spin-orbit (SO) coupling. We find that gated bilayer graphene under preserved time-reversal symmetry is a quantum valley Hall insulator for small Rashba SO coupling λR, and transitions to a strong TI when λR>U2+t2, where U and t are, respectively, the interlayer potential and tunneling energy. Different from a conventional quantum spin Hall state, the edge modes of our strong TI phase exhibit both spin and valley filtering, and thus share the properties of both quantum spin Hall and quantum valley Hall insulators. The strong TI phase remains robust in the presence of weak graphene intrinsic SO coupling.

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  • Received 6 September 2011

DOI:https://doi.org/10.1103/PhysRevLett.107.256801

© 2011 American Physical Society

Authors & Affiliations

Zhenhua Qiao1,*, Wang-Kong Tse1,†, Hua Jiang2,1, Yugui Yao3,1, and Qian Niu1,2

  • 1Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
  • 2International Center for Quantum Materials, Peking University, Beijing 100871, China
  • 3School of Physics, Beijing Institute of Technology, Beijing 100081, China

  • *zhqiao@physics.utexas.edu
  • wktse@physics.utexas.edu

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Vol. 107, Iss. 25 — 16 December 2011

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