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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)

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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