Time-resolved ARPES study on Ta<sub>2</sub>NiSe<sub>5</sub>

ORAL

Abstract

Ta2NiSe5 has been long proposed as an excitonic insulator, in which remarkable band flattening below the structural transition temperature at 328 K, as a result of the strong Coulomb attractive interactions between the conduction and valence bands. Recently, photo-excitation has been intensively used to explore non-equilibrium phases. Our previous result also confirms that Ta2NiSe5 is an excitonic insulator from the characteristic dynamical behavior [1]. In this work, we have used time-resolved ARPES (TARPES) to investigate the photo-excited non-equilibrium phases in Ta2NiSe5. We have discovered that intense photo-excitation induce a transient semimetalic state, which could not be realized under equilibrium. In order to gain insight on the mechanism of this phase transition, we have pursued the TARPES measurements with better signal-to-noise ratio enabled by use of the higher repetition rate laser system. We have observed oscillating behaviors corresponding to the coherent phonons in the ARPES intensity maps, which allowed us to identify which phonon mode is relevant to the metallization.

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Presenters

  • Takeshi L. Suzuki

    • Univ of Tokyo-Kashiwanoha

Authors

  • Takeshi L. Suzuki

    • Univ of Tokyo-Kashiwanoha

  • Yasushi Shinohara

    • School of Engineering, The Univ of Tokyo
    • School of Engineering, Univ. of Tokyo

  • Yangfan Lu

    • Dept. of Science, Univ of Tokyo

  • Mari Watanabe

    • Univ of Tokyo-Kashiwanoha

  • Jiadi Xu

    • Univ of Tokyo-Kashiwanoha

  • Kenichi L. Ishikawa

    • School of Engineering, Univ. of Tokyo

  • Hide Takagi

    • Dept. of Science, Univ of Tokyo

  • Minoru Nohara

    • Research Institute for Interdisciplinary Science, Okayama University

  • Naoyuki Katayama

    • Applied Physics, Nagoya University
    • Department of Applied Physics, Nagoya University

  • Hiroshi Sawa

    • Applied Physics, Nagoya University
    • Department of Applied Physics, Nagoya University
    • Nagoya University

  • Masami Fujisawa

    • Univ of Tokyo-Kashiwanoha

  • Teruto Kanai

    • Univ of Tokyo-Kashiwanoha

  • Nobuhisa Ishii

    • Univ of Tokyo-Kashiwanoha

  • Jiro Itatani

    • Univ of Tokyo-Kashiwanoha

  • Takashi Mizokawa

    • Department of Applied Physics, Waseda University
    • School of Advanced Science and Engineering, Waseda University

  • Shik Shin

    • Univ of Tokyo
    • University of Tokyo
    • Institute for Solid State Physics, University of Tokyo
    • Univ of Tokyo-Kashiwanoha
    • Institute for Solid State Physics, The University of Tokyo

  • Kozo Okazaki

    • Institute for Solid State Physics, University of Tokyo
    • Univ of Tokyo-Kashiwanoha