Disentangling Lattice and Electronic Instabilities in the Excitonic Insulator Candidate Ta2NiSe5 by Nonequilibrium Spectroscopy

Kota Katsumi, Alexandr Alekhin, Sofia-Michaela Souliou, Michael Merz, Amir-Abbas Haghighirad, Matthieu Le Tacon, Sarah Houver, Maximilien Cazayous, Alain Sacuto, and Yann Gallais
Phys. Rev. Lett. 130, 106904 – Published 8 March 2023
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Abstract

Ta2NiSe5 is an excitonic insulator candidate showing the semiconductor or semimetal-to-insulator (SI) transition below Tc=326K. However, since a structural transition accompanies the SI transition, deciphering the role of electronic and lattice degrees of freedom in driving the SI transition has remained controversial. Here, we investigate the photoexcited nonequilibrium state in Ta2NiSe5 using pump-probe Raman and photoluminescence spectroscopies. The combined nonequilibrium spectroscopic measurements of the lattice and electronic states reveal the presence of a photoexcited metastable state where the insulating gap is suppressed, but the low-temperature structural distortion is preserved. We conclude that electron correlations play a vital role in the SI transition of Ta2NiSe5.

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  • Received 15 November 2022
  • Accepted 14 February 2023

DOI:https://doi.org/10.1103/PhysRevLett.130.106904

© 2023 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Kota Katsumi1, Alexandr Alekhin1, Sofia-Michaela Souliou2, Michael Merz2,3, Amir-Abbas Haghighirad2, Matthieu Le Tacon2, Sarah Houver1, Maximilien Cazayous1, Alain Sacuto1, and Yann Gallais1

  • 1Université Paris Cité, CNRS, Matériaux et Phénoménes Quantiques, F-75013 Paris, France
  • 2Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
  • 3Karlsruhe Nano Micro Facility (KNMFi), Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany

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Issue

Vol. 130, Iss. 10 — 10 March 2023

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