The Realization of the Axion Insulator State in Quantum Anomalous Hall Sandwich Heterostructures

ORAL

Abstract

The topological magnetoelectric (TME) effect is a special version of the magnetoelectric effect, showing quantized response functions. The Z2 topological insulators (TIs) with gapped surfaces and time reversal invariant bulk state are predicted to show the TME effect, and are called axion insulators. We present the observation of the axion insulator state in a magnetically doped TI ((Bix, Sb1-x)2Te3) sandwich heterostructure, where the top and bottom layers are doped with V and Cr, respectively, and are separated by an undoped TI middle layer [arXiv: 1710.00471]. Magnetic force microscopy measurements confirm the existence of parallel and antiparallel magnetization of the two magnetic layers by sweeping the external magnetic field. Transport measurements unambiguously demonstrate the quantum anomalous Hall (QAH) state (parallel configuration), and the axion insulator state (antiparallel), where we observe a large longitudinal resistance and vanishing longitudinal and Hall conductance. Our findings thus show evidence for a phase of matter distinct from the established QAH state and provide a promising platform for the realization of the TME effect.

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Presenters

  • Di Xiao

    Department of Physics, Pennsylvania State University, Pennsylvania State University

Authors

  • Di Xiao

    Department of Physics, Pennsylvania State University, Pennsylvania State University

  • Jue Jiang

    Department of Physics, Pennsylvania State University

  • Jaeho Shin

    Department of Physics, Pennsylvania State University

  • Wenbo Wang

    Department of Physics and Astronomy, Rutgers University

  • Fei Wang

    Department of Physics, Pennsylvania State University

  • Yi-Fan Zhao

    Department of Physics, Pennsylvania State University

  • Chao-Xing Liu

    Department of Physics, Pennsylvania State University, Pennsylvania State University, The Pennsylvania State University, Physics, Pennsylvania State Univ, Department of Physics, Pennsylvania State Univ

  • Weida Wu

    Department of Physics and Astronomy, Rutgers University, Rutgers-Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Rutgers Univ, Physics and Astronomy, Rutgers Univ, Department of Physics and Astronomy, Rutgers, the State College of New Jersey

  • Moses Chan

    Department of Physics, Pennsylvania State University, Physics, Pennsylvania State Univ

  • Nitin Samarth

    Department of Physics and Material Research Institute, Pennsylvania State University, Department of Physics, Pennsylvania State University, Pennsylvania State University, Pennsylvania State Univ, Dept. of Physics, Pennsylvania State Univ, Physics, The Pennsylvania State University, Physics, Pennsylvania State University

  • Cui-Zu Chang

    Department of Physics, Pennsylvania State University, Pennsylvania State University, Department of Physics, The Pennsylvania State University, Physics, Pennsylvania State University