Emergence of excitonic superfluid at topological-insulator surfaces

ORAL

Abstract

Excitons are spin integer particles that were predicted to condense into a coherent quantum state at sufficiently low temperature more than 50 years ago. Nonetheless, transport of exciton condensates is not yet understood and it is unclear whether an exciton condensate is a superfluid or an insulating electronic crystal. Topological insulators (TIs) with massless particles and unique spin textures have been theoretically predicted as a promising platform for achieving exciton condensation. Here we report experimental evidence of excitonic superfluid phase at the surface of three-dimensional (3D) TIs. We unambiguously confirmed that electrons and holes are paired into charge neutral bound states by the electric field independent photocurrent distributions. And we observed a millimetre-long transport distance of these excitons up to 40 K, which strongly suggests dissipationless propagation. The robust macroscopic quantum states achieved with simple device architecture and broadband photoexcitation at relatively high temperature are expected to find novel applications in quantum computations and spintronics.

*This work was supported by National Science Foundation Grant DMR-1838532 and DMR-1710737.

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Presenters

  • Yasen Hou

    • University of California, Davis
    • University of california, Davis

Authors

  • Yasen Hou

    • University of California, Davis
    • University of california, Davis

  • Rui Wang

    • Shanghai Jiao Tong University

  • Rui Xiao

    • University of California, Davis
    • University of california, Davis

  • Luke McClintock

    • University of California, Davis
    • University of california, Davis

  • Henry Clark Travaglini

    • University of California, Davis
    • University of california, Davis

  • John Paulus Francia

    • University of California, Davis
    • University of california, Davis

  • Harry Fetsch

    • Harvey Mudd College

  • Onur Erten

    • Arizona State University
    • Rutgers University, New Brunswick
    • Department of Physics, Arizona State University

  • Sergey Savrasov

    • Physics, UC Davis
    • University of California, Davis
    • University of california, Davis

  • Baigeng Wang

    • Nanjing University

  • Antonio Rossi

    • University of California, Davis
    • University of california, Davis

  • Inna Vishik

    • University of California, Davis
    • University of california, Davis
    • Physics, University of California, Davis

  • Eli Rotenberg

    • Advanced Light Source, E.O. Lawrence Berkeley National Lab, Berkeley, CA 94720, USA
    • Advanced Light Source, Lawrence Berkeley National Laboratory
    • ALS, Lawrence National Berkeley Laboratory
    • Advanced Light Source, Lawrence Berkeley National Lab
    • Lawrence Berkeley National Laboratory
    • Advanced Light Source (ALS), E. O. Lawrence Berkeley National Laboratory, USA
    • Advanced Light Source, E. O. Lawrence Berkeley National Laboratory

  • Dong Yu

    • University of California, Davis
    • University of california, Davis