GW-BSE Study on the Interlayer Moiré Excitonic States in Twisted Bilayer WSe<sub>2</sub>

ORAL

Abstract

Recent experiments on twisted bilayer WSe2 have shown signatures of interlayer moiré excitons in a wide range of twist angles. The emission spectra of the excitonic states manifest strong valley polarization which is absent in naturally occurring 2H stacked homobilayer counterparts. However, the underlying mechanism of the excitonic states and their exotic polarization properties is still elusive. In this work, we investigate the interlayer moiré excitonic states in the twisted bilayer WSe2 using first-principles GW-BSE calculations. We first perform density functional theory (DFT) calculations and study how moiré potential and interlayer hybridization affect the spin-valley properties of the system. To investigate the quasiparticle and optical properties, we next perform GW and GW-BSE calculations with the recently developed pristine unit-cell matrix projection (PUMP) [1] method and explore the role of spin and valley degrees of freedom in the polarization properties of interlayer moiré excitons.

*This work is supported by the U.S. Department of Energy and the National Science Foundation.

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Publication: Naik, M. H. et al. Intralayer charge-transfer moiré excitons in van der Waals superlattices. Nature 609, 52–57 (2022)

Presenters

  • Woochang Kim

    • University of California at Berkeley and Lawrence Berkeley National Lab
    • University of California, Berkeley

Authors

  • Woochang Kim

    • University of California at Berkeley and Lawrence Berkeley National Lab
    • University of California, Berkeley

  • Mit H Naik

    • University of California, Berkeley
    • University of California at Berkeley and Lawrence Berkeley National Lab
    • University of California at Berkeley; Lawrence Berkeley National Lab

  • 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