Electric-field-switchable exciton polarons involving Γ-valley or K-valley Fermi sea in trilayer WSe<sub>2</sub>

ORAL

Abstract

The exciton polaron, a quasiparticle arising from many-particle interactions, is a well-explored phenomenon in optical spectra of charged monolayer transition metal dichalcogenides (TMDs). However, the exciton-polaron properties in multilayer TMDs are still not well understood. In this study, we investigate optical spectra of exciton polarons in 2H-stacked trilayer WSe2 dual-gate devices encapsulated by boron nitride. We find that the application of electric field can induce an abrupt change in the exciton-polaron spectra, which is attributed to the switching of the valence band maximum (VBM) between the Γ and K valleys. At weak electric fields, the VBM resides in the Γ valley, leading to the formation of exciton polarons involving the Fermi sea in the Γ valley. When the electric field exceeds a critical value, the VBM switches to the K valley, leading to the formation of exciton polarons involving the Fermi sea in the K valley. Our study elucidates the influence of band structure on the exciton polarons in trilayer WSe2, shedding light on the intriguing nature of exciton polarons in multilayer TMDs.

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Presenters

  • Tianyi Ouyang

    • University of California, Riverside

Authors

  • Tianyi Ouyang

    • University of California, Riverside

  • Ao Shi

    • University of California, Riverside

  • Takashi Taniguchi

    • Kyoto Univ
    • National Institute for Materials Science
    • Research Center for Materials Nanoarchitectonics
    • Research Center for Materials Nanoarchitectonics, National Institute for Materials Science
    • National Institute for Materials Sciences
    • NIMS
    • International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
    • National Institute for Material Science
    • International Center for Materials Nanoarchitectonics, NIMS, Japan
    • International Center for Materials Nanoarchitectonics, Tsukuba
    • National Institue for Materials Science
    • Kyoto University
    • National Institute of Materials Science
    • International Center for Materials Nanoarchitectonics and National Institute for Materials Science

  • Kenji Watanabe

    • National Institute for Materials Science
    • NIMS
    • Research Center for Electronic and Optical Materials, National Institute for Materials Science
    • Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
    • National Institute for Material Science

  • Yia-Chung Chang

    • Research Center for Applied Sciences, Academia Sinica, Taipei
    • Sinica

  • Chun Hung Lui

    • University of California, Riverside