Ultrafast dephasing from phonon-emission assisted intervalley scattering in MoSe<sub>2</sub> bilayers

ORAL

Abstract

Exciton dynamics have been investigated extensively in transition metal dichalcogenide (TMDC) monolayers, but comparatively little is known of their behavior in bilayers, due to the presence of multiple low-energy valleys in bilayer TMDC band structures. We find that bright exciton decoherence occurs on a much faster time scale in MoSe2 bilayers than in monolayers, and is limited by pure dephasing processes. Remarkable agreements between the measured and calculated homogeneous linewidths in both the monolayer and bilayer are found by taking into account all relevant exciton-phonon scattering processes. Our microscopic model identies that phonon-emission processes facilitate scattering events from the K valley to lower energy Γ and Λ valleys in the bilayer and induce pure dephasing.

*We gratefully acknowledge funding from NSF DMR-1808042, Department of Energy grant DE-SC0019398, Deutsche Forschungsgemeinschaft grants GRK 1558, CRC 787, and SFB 951, support from Swedish Research Council, project number 2018-00734.

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Presenters

  • Kevin Sampson

    • University of Texas at Austin

Authors

  • Kevin Sampson

    • University of Texas at Austin

  • Sophia Helmrich

    • Department of Optics and Atomic Physics, Technische Universität Berlin

  • Di Huang

    • University of Texas at Austin

  • Malte Selig

    • Institute for Theoretical Physics, Technische Universität Berlin

  • Kai Hao

    • University of Texas at Austin

  • Kha Tran

    • University of Texas at Austin
    • Department of Physics, The University of Texas at Austin
    • United States Naval Research Laboratory

  • Carter Young

    • University of Texas at Austin

  • Andreas Knorr

    • Institute for Theoretical Physics, Technische Universität Berlin

  • Ermin Malic

    • Chalmers University, Sweden
    • Department of Physics, Chalmers University of Technology

  • Ulrike Woggon

    • Department of Optics and Atomic Physics, Technische Universität Berlin

  • Xiaoqin (Elaine) Li

    • University of Texas at Austin
    • Physics, University of Texas at Austin
    • Department of Physics, University of Texas at Austin
    • U.T. Austin
    • Department of Physics, The University of Texas at Austin
    • Department of Physics, Center of Complex Quantum Systems, University of Texas at Austin

  • Nina Owschimikow

    • Department of Optics and Atomic Physics, Technische Universität Berlin