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Spatial and spectral signatures of intralayer moiré excitons in layered superlattices

ORAL

Abstract

Stacking of individual monolayers of layered materials like transition metal dichalcogenides with precise control of twist angle offers an unconventional bottom-up approach to design artificial superlattices of nanoscale periodicity. The concomitant moiré patterns in such superlattices modulate the spectral contribution and the spatial distribution of the excitonic states. These twist-tunable moiré excitons typically probed by optical spectroscopy techniques lack nanoscale spatial resolution and hence it is imperative to correlate these spectral signatures with other suitable nanoscale characterization techniques [1]. In this study, we demonstrate spatially and spectrally resolved signatures of distinct intralayer moire excitons by employing monochromated electron energy loss spectroscopy (EELS) on prototypes of closely aligned WS2/WSe2 stacks. The distinct moiré exciton spectral signatures at cryogenic temperatures from EELS correlate quite well with the energy resonances of the corresponding reflection contrast spectra for both WSe2 and WS2.

[1] Susarla, Sandhya, et al. arXiv:2207.13823 (2022).

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Presenters

  • Medha Dandu

    Lawrence Berkeley National Laboratory

Authors

  • Medha Dandu

    Lawrence Berkeley National Laboratory

  • Jordan Hachtel

    Oak Ridge National Lab

  • 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

  • Patrick Hays

    Arizona State University

  • Sriram Sankar

    Arizona State University

  • Elyse Barre

    Lawrence Berkeley National Laboratory

  • Takashi Taniguchi

    National Institute for Materials Science, Kyoto Univ, International Center for Materials Nanoarchitectonics, National Institute of Materials Science, Kyoto University, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-044, Japan, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, National Institute for Materials Science, Japan, National Institute For Materials Science, NIMS, National Institute for Material Science, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan, NIMS Japan

  • Kenji Watanabe

    National Institute for Materials Science, Research Center for Functional Materials, National Institute of Materials Science, Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-044, Japan, NIMS, Research Center for Functional Materials, National Institute for Materials Science, National Institute for Materials Science, Japan, Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan, NIMS Japan

  • 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

  • Felipe H da Jornada

    Stanford University, Stanford

  • Sefaatin Tongay

    Arizona State University

  • Peter Ercius

    Lawrence Berkeley National Laboratory

  • Archana Raja

    Lawrence Berkeley National Laboratory

  • Sandhya Susarla

    Arizona State University