Light-induced band asymmetries seen by trARPES and their excitonic origin

ORAL

Abstract

We studied photoexcited band structure and ultrafast phenomena in bulk MoS2 by using extreme-UV time- and angle-resolved photoemission spectroscopy (XUV-trARPES). We observed a light-induced transient spectral signature near valence band maximum with explicit asymmetric distributions in energy and momentum, featuring an unusual two-component decay behavior. We conducted theoretical calculations to understand these observations. We found that the excitonic correlations between electrons and holes play the critical role in understanding these light-induced band asymmetries consistently in energy, momentum, and time. Our work provides a new frame for studying ultrafast excitonic phenomena in optically dark materials, such as bulk semiconductors and excitonic insulators, by using photoelectron spectroscopy.

*We acknowledge the support from U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division under Contract No. DE-AC02-05-CH11231 (Ultrafast Materials Science program KC2203) and (Theory of Materials Program KC2301).We acknowledge the support from the NSF Center for Dynamics and Control of Materials with grant No. DMR1720595, NSF-DMR 1808751, Welch Foundation F-1672 and US Airforce FA2386-18-1-4097.

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Presenters

  • Yi Lin

    • Lawrence Berkeley National Laboratory

Authors

  • Yi Lin

    • Lawrence Berkeley National Laboratory

  • Yang-hao Chan

    • Academia Sinica
    • Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
    • Institute of Atomic and Molecular Sciences, Academia Sinica
    • Lawrence Berkeley National Laboratory

  • Woojoo Lee

    • University of Chicago

  • Chih-Kang Shih

    • University of Texas at Austin

  • Steven G Louie

    • University of California at Berkeley
    • University of California, Berkeley
    • University Of California, Berkeley
    • University of California at Berkeley and Lawrence Berkeley National Lab
    • University of California at Berkeley; Lawrence Berkeley National Lab
    • UC Berkeley
    • University of California at Berkeley, and Lawrence Berkeley National Laboratory
    • UC berkeley
    • Lawrence Berkeley National Laboratory
    • Physics Department, UC Berkeley and Lawrence Berkeley National Lab
    • Department of Physics, University of California at Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory
    • LBNL & UC Berkeley

  • Alessandra Lanzara

    • University of California, Berkeley