Intralayer moiré exciton states in transition metal dichalcogenide heterostructures: a GW-BSE study

ORAL

Abstract

Recent experimental measurements have shown signatures of novel exciton states in the moiré superlattices of transition metal dichalcogenide bilayer heterostructures. In the WS2/WSe2 heterostructure, the WSe2 “A” exciton resonance is found to split into multiple peaks as the twist angle between the two layers approaches zero [1]. This splitting is directly correlated to the formation of a large-scale (~8.5 nm) moiré pattern at zero twist angle. Computing the optical properties of this system by brute force using first principles is intractable owing to the large number of atoms (~4000) in the moiré superlattice and the requirement of a fine k-point sampling of the Brillouin zone. We demonstrate an efficient approximation to solve the GW plus Bethe-Salpeter equation of the reconstructed moiré which yields excitations with meV accuracy relative to the traditional approach. Using this method, we study the twist-angle dependence of the absorption spectrum of intralayer excitons in the WS2/WSe2 moiré superlattice.

[1] C. Jin, et al. Nature 567, 76–80 (2019)

*This work was supported by the US DOE at Lawrence Berkeley National Lab under contract no. DE-AC02-05CH11231 and the C2SEPEM under contract No. DE-AC02-05CH11231. Computational resources have been provided by NERSC, TACC and XSEDE.

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Presenters

  • Mit Naik

    • Department of Physics, University of California at Berkeley
    • University of California at Berkeley and Lawrence Berkeley National Laboratory
    • Department of physics, University of California at Berkeley, Berkeley, California

Authors

  • Mit Naik

    • Department of Physics, University of California at Berkeley
    • University of California at Berkeley and Lawrence Berkeley National Laboratory
    • Department of physics, University of California at Berkeley, Berkeley, California

  • Yang-hao Chan

    • Lawrence Berkeley National Laboratory
    • University of California at Berkeley and Lawrence Berkeley National Laboratory
    • University of California, Berkeley
    • Department of physics, University of California at Berkeley, Berkeley, California

  • Zhenglu Li

    • Department of Physics, University of California, Berkeley
    • UC Berkeley & Lawrence Berkeley National Laboratory
    • University of California at Berkeley, and Lawrence Berkeley National Laboratory
    • University of California at Berkeley and Lawrence Berkeley National Laboratory
    • Lawrence Berkeley National Laboratory
    • University of California, Berkeley
    • Lawrence Berkeley National Laboratory and University of California at Berkeley
    • Department of physics, University of California at Berkeley, Berkeley, California

  • Chin Shen Ong

    • University of California at Berkeley, and Lawrence Berkeley National Laboratory
    • Department of physics, University of California at Berkeley, Berkeley, California

  • Felipe Da Jornada

    • Stanford University
    • Materials Science and Engineering, Stanford University
    • Department of Materials Science and Engineering, Stanford University
    • Stanford Univ
    • Department of Materials Science and Engineering, Stanford University, Stanford, California

  • Steven G Louie

    • University of California, Berkeley
    • Department of Physics, University of California, Berkeley
    • University of California at Berkeley and Lawrence Berkeley National Laboratory
    • UC Berkeley & Lawrence Berkeley National Laboratory
    • University of California at Berkeley, and Lawrence Berkeley National Laboratory
    • Lawrence Berkeley National Laboratory
    • Department of physics, University of California at Berkeley, Berkeley, California