Title : Moiré excitons in generalized wigner crystals: A first-principles GW-BSE study

Generalized Wigner crystals (GWCs) emerge in transition-metal dichalcogenide (TMD) moiré superlattices at fractional carrier fillings due to strong electron correlations in flat bands. When such correlated insulating ground states are photoexcited, they give rise to unusual excitonic phases, Wigner crystalline excitons (WCEs), where the interplay between electronic and excitonic correlations fundamentally reshapes the exciton internal structure. However, a microscopic understanding of WCEs has remained elusive. Here, by enabling large-scale first-principles many-body GW-Bethe-Salpeter equation (GW-BSE) calculations on systems with nearly 10,000 atoms per supercell, we directly reveal the internal structure of WCEs in an angle-aligned MoSe₂/MoS₂ moiré heterostructure at hole fillings ν_h = 1/3 and 2/3. We find that the symmetry-breaking charge order of the GWC ground state propagates into the excited states: the excited electron density of the lowest-energy exciton does not follow the conduction band wavefunctions but instead closely tracks the excited hole density, which itself is pinned by the Wigner crystal. The electron-hole interaction dominates over the kinetic energy of free electron-hole pairs by more than an order of magnitude (exciton binding energies ~98–118 meV vs. bandwidth ~2–3 meV), making WCEs intrinsically correlation-driven. We further propose a photocurrent tunneling microscopy (PTM) experiment that can directly visualize the strongly correlated electron-hole pair distribution, providing an unambiguous experimental signature. Our work establishes a general computational framework for studying correlated excited-state phenomena in moiré quantum matter and highlights WCEs as a highly tunable mixed boson-fermion platform for exploring many-body interactions.

Dr. Jingyang You is an Associate Professor at the International Frontier Interdisciplinary Science Institute, Beihang University (BUAA). He received his Ph.D. in Condensed Matter Physics from the University of Chinese Academy of Sciences in 2020. He then conducted postdoctoral research at National University of Singapore and University of Southern California before joining BUAA in 2025. His research focuses on first-principles calculations of correlated quantum materials, including moiré excitonics, electron-phonon coupling in kagome superconductors, and topological quantum states. He has published over 40 papers as first/corresponding author in journals such as PNAS, Phys. Rev. Lett., JACS, and Natl. Sci. Rev.