Vanadium impurity state in the doped Sb$_{2}$Te$_{3}$ quantum anomalous Hall system

ORAL

Abstract

The quantum anomalous Hall (QAH) effect has recently been reported in the ferromagnetic topological insulator V-doped (Sb,Bi)$_{2}$Te$_{3}$. However, the microscopic origin of the insulating ferromagnetic ground state is unclear. We employed scanning tunnelling microscopy and spectroscopy on (Sb$_{1-x}$V$_{x}$)$_{2}$Te$_{3}$, and identified two types of V substitutions, in the first and second Sb layers beneath the surface. We found that, second-layer V substitutions induce a peak within the bulk gap, which may form an impurity band at high impurity concentration. However, first-layer V substitutions suppress the impurity state and locally induce a gap in the surface state. Our results clarified the contribution of the V impurity state to the electronic structure of this QAH system.

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Authors

  • Pengcheng Chen

    Harvard University

  • Yu Liu

    Harvard University

  • Yau Chuen Yam

    Harvard University, Harvard University and Univerisity of British Columbia

  • Yang He

    Harvard University

  • Chris Eckberg

    University of Maryland, Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park 20742, USA, Univ of Maryland-College Park

  • Joshua Samuel

    University of Maryland

  • Johnpierre Paglione

    Univ of Maryland-College Park, Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park 20742, USA, University of Maryland, Department of Physics, University of Maryland, MD, USA; Canadian Institute for Advanced Research, Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park, MD 20742, USA

  • Mohammad Hamidian

    Harvard Univeristy, University of California, Davis, Harvard University and University of California, Davis

  • Jennifer Hoffman

    Harvard University and University of British Columbia, Harvard University, Harvard University and Univerisity of British Columbia