A topological excitonic insulator

ORAL

Abstract

We will discuss the observation of a topological excitonic insulator phase in Ta₂Pd₃Te₅, where Coulomb interactions lead to exciton formation and condensation below T = 100 K, opening a topological gap. This excitonic insulator spontaneously breaks mirror symmetries but shows minimal structural coupling, as confirmed through spectroscopy, thermodynamic, and structural analyses. Scanning tunneling microscopy reveals gapless, topological boundary modes within this bulk excitonic insulator phase. Additionally, a secondary excitonic instability occurs near T = 5 K, breaking translational symmetry. Our findings reveal two symmetry-distinct correlated topological phases in one material, offering new insights into excitonic physics and potential technological applications.

*We acknowledge support from the Gordon and Betty Moore Foundation (GBMF9461), the US Department of Energy under the Basic Energy Sciences program (grant no. DOE/BES DE-FG-02-05ER46200), and Quantum Science Center (at Oak Ridge National Laboratory).

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Publication: https://arxiv.org/abs/2312.15862

Presenters

  • Shafayat Hossain

    • Princeton University

Authors

  • Shafayat Hossain

    • Princeton University

  • Zahid M Hasan

    • Princeton University

  • Zijia Cheng

    • Princeton University

  • Tyler A Cochran

    • Princeton University

  • Titus M Neupert

    • University of Zürich
    • University of Zurich
    • University of zurich

  • Songbo Zhang

    • University of Zürich
    • University of Zurich

  • Xiaoxiong Liu

    • University of Zurich

  • Zhiwei Wang

    • Beijing Institute of Technology

  • Yuxiao Jiang

    • Princeton University

  • Luis M Balicas

    • National High Magnetic Field Laboratory
    • Florida State University, National High Magnetic Field Laboratory