Inhibition of the photoinduced structural phase transition in the excitonic insulator Ta2NiSe5

Selene Mor, Marc Herzog, Johannes Noack, Naoyuki Katayama, Minoru Nohara, Hide Takagi, Annette Trunschke, Takashi Mizokawa, Claude Monney, Julia Stähler

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    34 Citations (Scopus)


    Femtosecond time-resolved midinfrared reflectivity is used to investigate the electron and phonon dynamics occurring at the direct band gap of the excitonic insulator Ta2NiSe5 below the critical temperature of its structural phase transition. We find that the phonon dynamics show a strong coupling to the excitation of free carriers at the Γ point of the Brillouin zone. The optical response saturates at a critical excitation fluence FC=0.30±0.08 mJ/cm2 due to optical absorption saturation. This limits the optical excitation density in Ta2NiSe5 so that the system cannot be pumped sufficiently strongly to undergo the structural change to the high-temperature phase. We thereby demonstrate that Ta2NiSe5 exhibits a blocking mechanism when pumped in the near-infrared regime, preventing a nonthermal structural phase transition.

    Original languageEnglish
    Article number115154
    JournalPhysical Review B
    Issue number11
    Publication statusPublished - Mar 26 2018

    ASJC Scopus subject areas

    • Electronic, Optical and Magnetic Materials
    • Condensed Matter Physics


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