Moiré fractional Chern insulators from topological bosons and trivial fermions

ORAL

Abstract

Recent realizations of fermionic fractional Chern insulators (FCIs) and anomalous Hall crystals have established moiré systems as a powerful platform for exploring correlated topological phases. Here, we predict the emergence of robust bosonic topological order arising from long-lived interlayer excitons consisting of holes in twisted bilayer WSe₂ and electrons in an additional MoSe₂ layer. In particular, exact diagonalization reveals that realistic long-range interactions stabilize Laughlin and non-Abelian Moore–Read states at filling factors 1/2 and 1 of the exciton Chern band present in this system. In parallel, we uncover Laughlin-like fermionic FCIs in topologically trivial bands of twisted multilayer graphene, where a strongly inhomogeneous quantum geometry drives topological order independent of band topology. Together, these results highlight the extraordinarily rich landscape of moiré quantum matter, encompassing both bosonic and fermionic topological order shaped by quantum geometry.

*We acknowledge funding by the Swedish Research Council (2018-00313 and 2024-04567), the Knut and Alice Wallenberg Foundation (2018.0460 and 2023.0256), and the Göran Gustafsson Foundation for Research in Natural Sciences and Medicine.

Publication: R. Perea-Causin, H. Liu, E. J. Bergholtz, Exciton fractional Chern insulators in moiré heterostructures, accepted in Physical Review Research, Preprint at arXiv:2504.08026 (2025).
H. Liu, R. Perea-Causin, Z. Liu, E. J. Bergholtz, Topological order without band topology in moiré graphene, Preprint at arXiv:2510.15027 (2025).

Presenters

  • Raul Perea-Causin

    • Stockholm University

Authors

  • Raul Perea-Causin

    • Stockholm University
  • Hui Liu

    • Stockholm University
  • Zhao Liu

    • Zhejiang University
  • Emil J. Bergholtz

    • Stockholm Univ
    • Stockholm University