Ultrafast Electronic Band Gap Control in an Excitonic Insulator

Selene Mor, Marc Herzog, Denis GoleŽ, Philipp Werner, Martin Eckstein, Naoyuki Katayama, Minoru Nohara, Hide Takagi, Takashi Mizokawa, Claude Monney, Julia Stähler

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    Abstract

    We report on the nonequilibrium dynamics of the electronic structure of the layered semiconductor Ta2NiSe5 investigated by time- and angle-resolved photoelectron spectroscopy. We show that below the critical excitation density of FC=0.2 mJ cm-2, the band gap narrows transiently, while it is enhanced above FC. Hartree-Fock calculations reveal that this effect can be explained by the presence of the low-temperature excitonic insulator phase of Ta2NiSe5, whose order parameter is connected to the gap size. This work demonstrates the ability to manipulate the band gap of Ta2NiSe5 with light on the femtosecond time scale.

    Original languageEnglish
    Article number086401
    JournalPhysical Review Letters
    Volume119
    Issue number8
    DOIs
    Publication statusPublished - 2017 Aug 23

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    ASJC Scopus subject areas

    • Physics and Astronomy(all)

    Cite this

    Mor, S., Herzog, M., GoleŽ, D., Werner, P., Eckstein, M., Katayama, N., Nohara, M., Takagi, H., Mizokawa, T., Monney, C., & Stähler, J. (2017). Ultrafast Electronic Band Gap Control in an Excitonic Insulator. Physical Review Letters, 119(8), [086401]. https://doi.org/10.1103/PhysRevLett.119.086401