Quantum spin Hall effect in two-dimensional transition metal dichalcogenides

  • Xiaofeng Qian
    Department of Nuclear Science and Engineering and Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
  • Junwei Liu
    Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
  • Liang Fu
    Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
  • Ju Li
    Department of Nuclear Science and Engineering and Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

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説明

<jats:p> Quantum spin Hall (QSH) effect materials feature edge states that are topologically protected from backscattering. However, the small band gap in materials that have been identified as QSH insulators limits applications. We use first-principles calculations to predict a class of large-gap QSH insulators in two-dimensional transition metal dichalcogenides with 1T′ structure, namely, 1T′-MX <jats:sub>2</jats:sub> with M = (tungsten or molybdenum) and X = (tellurium, selenium, or sulfur). A structural distortion causes an intrinsic band inversion between chalcogenide- <jats:italic>p</jats:italic> and metal- <jats:italic>d</jats:italic> bands. Additionally, spin-orbit coupling opens a gap that is tunable by vertical electric field and strain. We propose a topological field effect transistor made of van der Waals heterostructures of 1T′-MX <jats:sub>2</jats:sub> and two-dimensional dielectric layers that can be rapidly switched off by electric field through a topological phase transition instead of carrier depletion. </jats:p>

収録刊行物

  • Science

    Science 346 (6215), 1344-1347, 2014-12-12

    American Association for the Advancement of Science (AAAS)

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