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Updated: Apr 2, 2026
08:04
Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
9.1K
Moiré excitons in generalized Wigner crystals
Jing-Yang You1, Chih-En Hsu1,2, Zien Zhu1
1Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089.
Summary
Strong Coulomb interactions in moiré superlattices create Wigner crystals. This study reveals the structure of Wigner crystalline excitons (WCEs) using advanced calculations, offering insights into correlated electronic and excitonic phases.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Mechanics
Background:
- Moiré superlattices in transition-metal dichalcogenide bilayers exhibit strong Coulomb interactions and narrow bands, leading to correlated insulating states known as Wigner crystals.
- Excited states in these systems involve moiré excitons, whose formation is influenced by Wigner-crystal ground states, indicating a complex interplay of electronic and excitonic correlations.
Purpose of the Study:
- To provide a microscopic description of Wigner crystalline excitons (WCEs) in moiré heterostructures.
- To understand the influence of ground-state Wigner crystals on excited-state excitonic properties.
- To explore potential experimental probes for these correlated excitonic states.
Main Methods:
- First-principles many-body GW-Bethe-Salpeter equation calculations.
- Investigation of angle-aligned MoSe2/MoS2 moiré heterostructures at specific hole fillings (1/3 and 2/3).
Main Results:
- Directly revealed the internal structures of WCEs.
- Demonstrated the propagation of correlation effects from ground to excited states, influencing WCE real-space characteristics.
- Found that strong two-particle excitonic correlations dominate over kinetic energy, similar to strong single-particle correlations in flat bands.
Conclusions:
- WCEs exhibit strong excited-state correlation effects.
- Proposed photocurrent tunneling microscopy (PTM) as an experimental method to probe these effects.
- Established WCEs as a tunable platform for studying many-body interactions and mixed boson-fermion phenomena.
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