Stability of symmetry required 2D topological insulators: ab-inito calculations of point defects in monolayer WTe2

ORAL

Abstract

The prediction of a 2D TI state in monolayer WTe2 has stimulated large excitement and an immense experimental effort. In what we call symmetry required TIs, such as graphene or WTe2, defects can act as trivial mass terms that can destroy the 2D TI state at a low critical disorder strength or defect concentration. However little is known about the types and energetics of defects that can occur in monolayer WTe2 and their effects on the electronic structure.We therefore calculate the formation energies of point defects of monolayer WTe2 in the 1T' structure. Three defects, all of them adatoms, have negative formation energies, while all other defects have large positive formation energies. The small difference in electronegativity between W and Te leads to a covalent network of bonds with strong contributions of both W-d and Te-p states around the Fermi energy. We show that the adatoms with negative formation energies are weak perturbations that do not influence the 2D TI state, while the other defects can induce a phase transition to a trivial, insulating state. Additionally, we present STM images of Te-adatoms on mono-, bi- and trilayers of WTe2 that agree well with STM images reported in the literature.

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Presenters

  • Lukas Muechler

    Chemistry, Princeton University, Department of Chemistry, Princeton University

Authors

  • Lukas Muechler

    Chemistry, Princeton University, Department of Chemistry, Princeton University

  • Wei Hu

    Institute of Physics,Chinese Academy of Sciences, National Lab for Superconductivity, Institute of Physics, Chinese Academy of Sciences (CAS), Computational Research Division, Lawrence Berkeley National Laboratory

  • Chao Yang

    Lawrence Berkeley National Laboratory, Computational Research Division, Lawrence Berkeley National Laboratory

  • Lin Lin

    Department of Mathematics, University of California Berkeley

  • Roberto Car

    Department of Chemistry, Princeton, Department of Chemistry, Princeton Univ, Department of Chemistry , Princeton University, Princeton University, Physics, Princeton University, Department of Chemistry, Princeton University