Phonon dispersion and self energy evolution in S-doped quasi-1D Ta<sub>2</sub>NiSe<sub>5</sub>

ORAL

Abstract

Ta2NiSe5 is considered as an excitonic insulator candidate where Coulomb interaction between electrons and holes leads to an ostensible exciton condensation. However, phonons are considered to play an important role [1]. Using inelastic x-ray scattering, an anomalous shortening of the phonon lifetime near Brillouin zone center is observed, indicating the instability of the phonons. Combining the electronic density of state extracted from angle-resolved photoemission spectra with the imaginary part of phonon self energy, the electron-phonon coupling strength is estimated to fall in a strong coupling regime. We also report structural hardening with S-doping indicated in the low-energy phonon spectra. In this process, rapidly dwindling electron phonon coupling is seen to accompany the precipitous drop of the structural transition temperature.

[1] C. Chen et al. arXiv:2203.06817

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Presenters

  • zhibo kang

    • Yale University

Authors

  • zhibo kang

    • Yale University

  • Ayman H Said

    • Argonne National Laboratory

  • Ahmet Alatas

    • Argonne National Laboratory

  • Weichen Tang

    • University of California, Berkeley

  • Jacob Ruff

    • Cornell University

  • Xiang Chen

    • University of California, Berkeley

  • Robert J Birgeneau

    • University of California, Berkeley

  • Steven G Louie

    • University of California at Berkeley
    • University of California, Berkeley
    • University Of California, Berkeley
    • University of California at Berkeley and Lawrence Berkeley National Lab
    • University of California at Berkeley; Lawrence Berkeley National Lab
    • UC Berkeley
    • University of California at Berkeley, and Lawrence Berkeley National Laboratory
    • UC berkeley
    • Lawrence Berkeley National Laboratory
    • Physics Department, UC Berkeley and Lawrence Berkeley National Lab
    • Department of Physics, University of California at Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory
    • LBNL & UC Berkeley

  • Yao Wang

    • Clemson University

  • Yu He

    • Yale University