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Probing Topological Surface States at Room Temperature in (Bi<sub>1-x</sub>Sb<sub>x</sub>)<sub>2</sub>Te<sub>3 </sub>Films

POSTER

Abstract

BiSbTe alloys are a part of an intriguing class of quantum materials known as topological insulators (TIs). We present our investigation of the local band structure of topologically insulating (Bi1-xSbx)2Te3 thin films using scanning tunneling microscopy/spectroscopy (STM/S) and magneto-transport (MT) measurements. Both STS and Hall transport measurements reveal a tunable electronic structure, with a n-type to p-type crossover for (Bi1-xSbx)2Te3 thin films at x ≈ 0.6. However, Hall measurements show n-type conduction while STS shows p-type conduction for films of varying thicknesses. This n/p anomaly is due to the distinct transport behaviors of the bulk and surface states. We directly probe both bulk and surface states in these films using STS. Both the Fermi level and the Dirac point are located inside the bulk band gap, indicating bulk-like insulating behavior with accessible surface states. We further discuss bulk and surface contributions to conduction. Prior to this work, direct detection of topological surface states in BiSbTe systems has been achieved only for T<10 K. This work demonstrates the first direct measurement of topological surface states using STS at room temperature for any material.

Presenters

  • Christian Greenhill

    Materials Science and Engineering, University of Michigan, Department of Materials Science & Engineering, University of Michigan, Department of Materials Science & Engineering, Northwestern University, University of Michigan

Authors

  • Christian Greenhill

    Materials Science and Engineering, University of Michigan, Department of Materials Science & Engineering, University of Michigan, Department of Materials Science & Engineering, Northwestern University, University of Michigan

  • Jenna C Walrath

    Intel Corporation

  • Vladimir A Stoica

    Pennsylvania State University, Argonne National Laboratory, Department of Physics, University of Michigan

  • Alexander Chang

    Department of Materials Science & Engineering, Northwestern University, Northwestern University

  • Yen-Hsiang Lin

    Department of Physics, University of Michigan, Physics, National TsingHua University

  • Carl T Boone

    Department of Physics, University of Michigan

  • Roy Clarke

    Department of Physics, University of Michigan

  • Ctirad Uher

    Department of Physics, University of Michigan

  • Cagliyan Kurdak

    Department of Physics, University of Michigan, University of Michigan

  • Rachel Goldman

    Materials Science and Engineering, University of Michigan, Department of Materials Science & Engineering, University of Michigan, Department of Materials Science and Engineering, University of Michigan, University of Michigan, Materials Science Engineering, University of Michigan