APS Logo

Gapped surface states in axion insulator candidate EuIn2As2 imaged by Scanning Tunneling Microscopy

ORAL

Abstract

Axion insulators are a proposed class of magnetic topological insulators in which time-reversal-symmetry (TRS) is broken either intrinsically or externally. EuIn2As2 is predicted to be an axion insulator that intrinsically breaks TRS. Here we use scanning tunneling microscopy (STM) and quasiparticle interference (QPI) imaging to measure the band structure of EuIn2As2. We discover three types of cleaved surfaces through imaging on pristine, La-doped, and Sb-doped samples: a 2x1 reconstructed Eu surface, a maze-like reconstruction of the In layer, and an intermediate As layer. Our QPI imaging on the Eu 2x1 surface shows scattering vectors corresponding to both bulk bands and surface states. We identify a bulk band gap ~ 150 meV and a surface state gap ~ 50 meV, which support the theoretical prediction that EuIn2As2 is an axion insulator. Our findings support EuIn2As2 as a platform to study axion insulator related phenomena.

–

Publication: One planned paper: Gapped surface states in axion insulator candidate EuIn2As2 imaged by Scanning Tunneling Microscopy

Presenters

  • Yizhe Sun

    Harvard University

Authors

  • Yizhe Sun

    Harvard University

  • Yu Liu

    Harvard University

  • Christian E Matt

    Harvard University

  • Harris S Pirie

    Harvard University

  • Jennifer E Hoffman

    Harvard University, Physics, Harvard University, Department of Physics, Harvard University

  • Lin-Lin Wang

    Ames National Laboratory, Ames Lab

  • Brinda Kuthanazhi

    Iowa State University

  • Paul C Canfield

    Iowa State University, Ames National Laboratory, Ames National Laboratory/Iowa State University

  • Sergey L Bud'ko

    Iowa State University, Ames National Laboratory, Ames Laboratory, U.S. DOE and Department of Physics and Astronomy, Iowa State University, Ames Laboratory