Robust Moire Exciton Coherence in a Twisted MoSe2 Bilayer

ORAL

Abstract

Moire superlattices provide a versatile platform to engineer many-body excited states in atomically thin semiconductors. Transition metal dichalcogenides (TMDs) are known host exciton resonances with large oscillator strength, and thus, rapidly radiative decays. While exciton quantum dynamics in TMD monolayers and natural bilayers are found to be determined by exciton radiative decay and phonon-assisted valley scatterings, respectively, quantum dynamics of moire excitons have never been experimentally investigated.

Here, we study a twisted MoSe2 bilayer with a small twist angle from the near-H stacking style. The homogeneous linewidth or the dephasing time of moire excitons is measured using two-dimensional electronic coherence spectroscopy (2DCES) and compared with a MoSe2 monolayer. Although the homogeneous linewidth of the moire exciton is broader than that of monolayer excitons at low temperatures, it is remarkably robust against temperature increases. This temperature-independent exciton coherence is unexpected and likely arises from a modified exciton–phonon interaction in moire superlattices.

*We gratefully acknowledge funding the Department of Energy, Office of Basic Energy Sciences under grant DE-SC0019398, the Army Research Office via grant W911NF-25-1-0058, and the Welch Foundation Chair F-0014.

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Presenters

  • Xiaohui Liu

    • University of Texas at Austin

Authors

  • Xiaohui Liu

    • University of Texas at Austin

  • Kai Hao

    • University of Texas at Austin

  • Jiwoong Kim

    • University of Texas at Austin

  • Albert Liu

    • Brookhaven National Laboratory (BNL)

  • Zhida Liu

    • University of Texas at Austin

  • Madalyn Gragg

    • University of Texas at Austin

  • Huda Hashmi

    • University of Texas at Austin

  • Kenji Watanabe

    • National Institute for Materials Science
    • Research Center for Functional Materials, National Institute of Materials Science, 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan

  • Takashi Taniguchi

    • National Institute for Materials Science
    • Research Center for Materials Nanoarchitectonics, National Institute for Materials Science
    • International Center for Materials Nanoarchitectonics, National Institute of Materials Science, 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan
    • Research Center for Functional Materials, National Institute of Materials Science, 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan

  • Jesper Levinsen

    • Monash University

  • Meera Parish

    • Monash University

  • Mit Naik

    • University of Texas, Austin
    • University of Texas at Austin
    • The University of Texas at Austin

  • Xiaoqin Elaine Li

    • University of Texas at Austin