Weak topological insulator state in quasi-one-dimensional bismuth iodide observed by surface-selective nano-ARPES

ORAL

Abstract

Recently, various materials have been confirmed to be topologically non-trivial by angle-resolved photoemission spectroscopy (ARPES) [1]. Despite intensive research on topological materials, a weak topological insulator (WTI) has so far remained hypothetical, since topological surface states (TSS) emerge only on the side surfaces, which are usually undetectable by conventional ARPES. We have overcome this difficulty by employing newly developed nano-ARPES. Its high spatial resolution allows us to perform surface selective measurements, which is necessary for the discovery of a WTI state in real 3D crystals.
In this contribution, we provide first experimental evidence for a WTI state in quasi-one-dimensional β-Bi4I4. The crystal has naturally cleavable top and side surfaces both stacked via van-der-Waals forces, and TSSs emerge only on the side surface as the WTI phase [2,3]. Our nano-ARPES results reveal quasi-1D Dirac-like surface state emerge only on the side surface whlie the top surface is topologically dark, which is the hall mark of the WTI state in β-Bi4I4 [4].
[1] M. Z. Hasan and C. L. Kane, Rev. Mod. Phys. 82, 3045 (2010).
[2] G. Autès et al., Nat. Mater. 15, 154 (2015).
[3] C.-C. Liu et al., Phys. Rev. Lett. 116, 66801 (2016).
[4] R. Noguchi et al., arXiv: 1802.03860 (2018).

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Presenters

  • Ryo Noguchi

    Institute for Solid State Physics, University of Tokyo

Authors

  • Ryo Noguchi

    Institute for Solid State Physics, University of Tokyo

  • Takanari Takahashi

    Materials and Structures Laboratory, Tokyo Institute of Technology

  • Kenta Kuroda

    Institute for Solid State Physics, University of Tokyo

  • Masayuki Ochi

    Department of Physics, Osaka University, Osaka University

  • Tetsuro Shirasawa

    National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology

  • Cédric Bareille

    Institute for Solid State Physics, University of Tokyo

  • Masato Sakano

    Institute for Solid State Physics, University of Tokyo

  • Mitsuhiro Nakayama

    Institute for Solid State Physics, University of Tokyo

  • Matthew Watson

    University of St Andrews, School of Physics and Astronomy, University of St. Andrews, Diamond Light Source, School of Physics and Astronomy, University of St Andrews, St. Andrews KY16 9SS, United Kingdom

  • Koichiro Yaji

    Institute for Solid State Physics, University of Tokyo

  • Ayumi Harasawa

    Institute for Solid State Physics, University of Tokyo

  • Hideaki Iwasawa

    Diamond Light Source

  • Pavel Dudin

    Diamond Light Source

  • Timur Kim

    Diamond Light Source, Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, United Kingdom

  • Moritz Hoesch

    DESY, Photon Science, Deutsches Elektronen-Synchrotron

  • Viktor Kandyba

    Elettra-Sincrotrone Trieste, Elettra - Sincrotrone Trieste S.C.p.A

  • Alessio Giampietri

    Elettra-Sincrotrone Trieste

  • Alexei Victorovich Barinov

    Elettra-Sincrotrone Trieste, Elettra - Sincrotrone Trieste S.C.p.A

  • Shik Shin

    Institute for Solid State Physics, the University of Tokyo, Japan, Institute for Solid State Physics, University of Tokyo, Institute for Solid State Physics, The University of Tokyo

  • Ryotaro Arita

    RIKEN, RIKEN Center for Emergent Matter Science, Department of Applied Physics and Quantum-Phase Electronics Center, University of Tokyo, University of Tokyo, University of Tokyo and RIKEN CEMS

  • Takao Sasagawa

    Materials and Structures Laboratory, Tokyo Institute of Technology, Tokyo Inst. of Tech.

  • Takeshi Kondo

    ISSP, University of Tokyo, Institute for Solid State Physics, University of Tokyo, University of Tokyo