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Phys. Rev. B 76, 045302 (2007) [17 pages]

Topological insulators with inversion symmetry

Liang Fu and C. L. Kane
Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
Received 14 November 2006; revised 17 January 2007; published 2 July 2007

Topological insulators are materials with a bulk excitation gap generated by the spin-orbit interaction that are different from conventional insulators. This distinction is characterized by Z2 topological invariants, which characterize the ground state. In two dimensions, there is a single Z2 invariant that distinguishes the ordinary insulator from the quantum spin-Hall phase. In three dimensions, there are four Z2 invariants that distinguish the ordinary insulator from “weak” and “strong” topological insulators. These phases are characterized by the presence of gapless surface (or edge) states. In the two-dimensional quantum spin-Hall phase and the three-dimensional strong topological insulator, these states are robust and are insensitive to weak disorder and interactions. In this paper, we show that the presence of inversion symmetry greatly simplifies the problem of evaluating the Z2 invariants. We show that the invariants can be determined from the knowledge of the parity of the occupied Bloch wave functions at the time-reversal invariant points in the Brillouin zone. Using this approach, we predict a number of specific materials that are strong topological insulators, including the semiconducting alloy Bi1−xSbx as well as alpha-Sn and HgTe under uniaxial strain. This paper also includes an expanded discussion of our formulation of the topological insulators in both two and three dimensions, as well as implications for experiments.

©2007 The American Physical Society

URL: http://link.aps.org/doi/10.1103/PhysRevB.76.045302
DOI: 10.1103/PhysRevB.76.045302
PACS: 73.43.-f; 72.25.Hg; 73.20.-r; 85.75.-d
  • 73.43.-f
    Quantum Hall effects
  • 72.25.Hg
    Electrical injection of spin polarized carriers
  • 73.20.-r
    Electron states at surfaces and interfaces
  • 85.75.-d
    Magnetoelectronics; spintronics: devices exploiting spin polarized transport or integrated magnetic fields
  • YEAR: 2007
KEYWORDS: ground states, Brillouin zones, bismuth compounds, quantum Hall effect, mercury compounds, II-VI semiconductors

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