Dipole Ladders with Giant Hubbard U in a Moiré Exciton Lattice

ORAL

Abstract

Two-dimensional semiconductor moiré superlattices have emerged as a powerful platform for engineering correlated electronic phenomena. Moreover, optical excitation creates charge neutral interlayer excitons with an out-of-plane electric dipole. Strong onsite dipole-dipole interaction promises the formation of correlated bosonic states, akin to the Mott states of electrons, but its observation remains elusive. Here, we report a giant exciton Hubbard U and consequent dipole ladders with spin- and electron-filling dependence in WSe2/WS2 moiré superlattices. By measuring interlayer exciton photoluminescence as a function of excitation intensity, we identify successive new peaks emerge with an energy separation of ~34 meV above the ground state. This corresponds to the sequential injection of excitons into a single site with an energy cost to overcome the remarkably large exciton Hubbard U, forming a dipole ladder. By measuring time-resolved photoluminescence, we also find that the interlayer exciton decay dynamics display a sequential cascaded decay down the dipole ladder. Based on findings of local magnetic moments at two holes per moiré cell, we show that excitons can also fill a second moiré orbital, establishing the two-orbital nature of the moiré potential landscape. Our results pave the way for investigating the Bose-Hubbard model with possible exciton crystal phases in interacting opto-moiré quantum matter.

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Publication: 1. Dipole Ladders with Giant Hubbard U in a Moiré Exciton Lattice, H. Park et. al, (2022, under revision)
2. Intercell Moiré Exciton Complexes in Electron Lattice, X. Wang*, X. Zhang*, J. Zhu*, H. Park* et. al, arXiv:2206.08424 (2022, under revision)

Presenters

  • Heonjoon Park

    • University of Washington

Authors

  • Heonjoon Park

    • University of Washington

  • Jiayi Zhu

    • University of Washington

  • Xi Wang

    • University of Washington

  • Yingqi Wang

    • University of Washington

  • William G Holtzmann

    • University of Washington

  • Kyle Hwangbo

    • University of Washington

  • 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

  • Jiaqiang Yan

    • Oak Ridge National Laboratory
    • Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA

  • Liang Fu

    • Massachusetts Institute of Technology MIT
    • Massachusetts Institute of Technology

  • Ting Cao

    • University of Washington
    • Department of Materials Science & Engineering, University of Washington

  • Di Xiao

    • University of Washington
    • 1. Department of Materials Science & Engineering, University of Washington, Seattle WA 98915 2. Department of Physics, University of Washington, Seattle WA 98915
    • Department of Materials Science & Engineering, Department of Physics, University of Washington; Pacific Northwest National Laboratory

  • Daniel R Gamelin

    • University of Washington

  • Hongyi Yu

    • Sun Yat-Sen University

  • Wang Yao

    • The University of Hong Kong

  • Xiaodong Xu

    • University of Washington