Signatures of the excitonic insulator phase of monolayer WTe<sub>2</sub> from photoemission spectra

ORAL

Abstract

Evidence has recently been presented that, in the two-dimensional WTe2 monolayer, electrons and holes bound by Coulomb attraction—excitons—spontaneously form at thermal equilibrium [1]. The ground state, which has been probed so far mostly by electrical transport measurements, is naturally interpreted within the paradigm of the long-sought-after ‘excitonic insulator’. Here, we report angle-resolved photoemission spectra of WTe2 monolayers for different temperatures and doping levels, controlled by in-situ electrostatic gating, and compare them with spectral weight maps from a self-consistent many-body theory of the excitonic insulator. This theory, built on density functional theory calculations, takes into account both spin-orbit and inter-valley coupling. The measured and predicted spectra are consistent, signaling that improved experimental intensity should be sufficient to establish the quantitative correctness of the predicted spectral modifications due to the excitonic insulator formation.

[1] Sun et al., Nature Physics 18, 94 (2022).

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Presenters

  • Massimo Rontani

    • CNR Institute for Nanoscience

Authors

  • Paul V Nguyen

    • University of Washington

  • Claudia Cardoso

    • CNR Institute for Nanoscience

  • Aalok Tiwari

    • Carnegie Mellon University

  • SOUVIK SASMAL

    • Carnegie Mellon University

  • I-Hsuan Kao

    • Carnegie Mellon University

  • Christopher Jozwiak

    • ALS, LBNL, Berkeley
    • Lawrence Berkeley National Lab
    • Lawrence Berkeley National Laboratory
    • Advanced Light Source, E.O. Lawerence Berkeley National Laboratory
    • Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA

  • Aaron Bostwick

    • ALS, LBNL, Berkeley
    • Lawrence Berkeley National Lab
    • Lawrence Berkeley National Laboratory
    • Advanced Light Source, LBNL
    • Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA

  • Eli Rotenberg

    • ALS, LBNL, Berkeley
    • Lawrence Berkeley National Laboratory
    • Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA

  • Jyoti Katoch

    • Carnegie Mellon University

  • Daniele Varsano

    • CNR Institute for Nanoscience

  • Elisa Molinari

    • University of Modena & Reggio Emilia

  • Massimo Rontani

    • CNR Institute for Nanoscience

  • David H Cobden

    • University of Washington