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Evidence for a topological excitonic insulator in InAs/GaSb bilayers

Author

Listed:
  • Lingjie Du

    (Rice University)

  • Xinwei Li

    (Rice University)

  • Wenkai Lou

    (Institute of Semiconductors, Chinese Academy of Sciences)

  • Gerard Sullivan

    (Teledyne Scientific and Imaging)

  • Kai Chang

    (Institute of Semiconductors, Chinese Academy of Sciences)

  • Junichiro Kono

    (Rice University
    Rice University
    Rice University)

  • Rui-Rui Du

    (Rice University
    Peking University)

Abstract

Electron–hole pairing can occur in a dilute semimetal, transforming the system into an excitonic insulator state in which a gap spontaneously appears at the Fermi surface, analogous to a Bardeen–Cooper–Schrieffer (BCS) superconductor. Here, we report optical spectroscopic and electronic transport evidence for the formation of an excitonic insulator gap in an inverted InAs/GaSb quantum-well system at low temperatures and low electron–hole densities. Terahertz transmission spectra exhibit two absorption lines that are quantitatively consistent with predictions from the pair-breaking excitation dispersion calculated based on the BCS gap equation. Low-temperature electronic transport measurements reveal a gap of ~2 meV (or ~25 K) with a critical temperature of ~10 K in the bulk, together with quantized edge conductance, suggesting the occurrence of a topological excitonic insulator phase.

Suggested Citation

  • Lingjie Du & Xinwei Li & Wenkai Lou & Gerard Sullivan & Kai Chang & Junichiro Kono & Rui-Rui Du, 2017. "Evidence for a topological excitonic insulator in InAs/GaSb bilayers," Nature Communications, Nature, vol. 8(1), pages 1-8, December.
    • Handle: RePEc:nat:natcom:v:8:y:2017:i:1:d:10.1038_s41467-017-01988-1
    DOI: 10.1038/s41467-017-01988-1
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