Observation of Moiré Excitons in WSe2/WS2 Heterostructure Superlattices

Abstract

Moiré superlattices provide a powerful tool to engineer novel quantum phenomena in two-dimensional (2D) heterostructures, where the interactions between the atomically thin layers qualitatively change the electronic band structure of the superlattice. For example, mini-Dirac points, tunable Mott insulator states, and the Hofstadter butterfly can emerge in different types of graphene/boron nitride moiré superlattices, while correlated insulating states and superconductivity have been reported in twisted bilayer graphene moiré superlattices. In addition to their dramatic effects on the single particle states, moiré superlattices were recently predicted to host novel excited states, such as moiré exciton bands. Here we report the first observation of moiré superlattice exciton states in nearly aligned WSe2/WS2 heterostructures. These moiré exciton states manifest as multiple emergent peaks around the original WSe2 A exciton resonance in the absorption spectra, and they exhibit gate dependences that are distinctly different from that of the A exciton in WSe2 monolayers and in large-twist-angle WSe2/WS2 heterostructures. The observed phenomena can be described by a theoretical model where the periodic moiré potential is much stronger than the exciton kinetic energy and creates multiple flat exciton minibands. The moiré exciton bands provide an attractive platform to explore and control novel excited state of matter, such as topological excitons and a correlated exciton Hubbard model, in transition metal dichalcogenides.

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• Moiré excitons: from programmable quantum emitter arrays to spin-orbit coupled artificial lattices
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Cited by in corpus (24)

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• Superlattices based on van der Waals 2D materials
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• The optical properties of few-layer InSe
• Nano-photocurrent mapping of local electronic structure in twisted bilayer graphene
• Theory of tunable flux lattices in the homobilayer moiré of twisted and uniformly strained transition metal dichalcogenides
• Electrically Controlled Two-Dimensional Electron-Hole Fluids
• Low-frequency Raman scattering in WSe${}_2$-MoSe${}_2$ heterobilayers: Evidence for atomic reconstruction
• Topological charge pumping in twisted bilayer graphene
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• A Cleanroom in a Glovebox
• Lithium intercalation in MoS${}_2$ bilayers and implications for moiré flat bands
• Interlayer exciton-polaron in atomically thin semiconductors
• High resolution imaging of reconstructed domains and moire patterns in functional van der Waals heterostructure devices
• WSe2/WS2 moiré superlattices: a new Hubbard model simulator
• Quantum Hall effects of exciton condensate in topological flat bands
• Moiré lattice-induced formation and tuning of hybrid dipolar excitons in twisted WS${}_2$/MoSe${}_2$ heterobilayers
• Electrically controllable router of interlayer excitons
• Highly tunable quantum light from moiré trapped excitons
• Exciton Transport under Periodic Potential in MoSe2/WSe2 Heterostructures
• Angle-dependence of interlayer coupling in twisted transition metal dichalcogenide heterobilayers