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The advent of moiré platforms for engineered quantum matter has led to discoveries of integer and fractional quantum anomalous Hall effects, with predictions for correlation-driven topological states based on electron crystallization. Here, we report an array of trivial and topological insulators formed in a moiré lattice of rhomobohedral pentalayer graphene (R5G). At a doping of one electron per moiré unit cell ( ), we see a correlated insulator with a Chern number that can be tuned between and by an electric displacement field. This is accompanied by a series of additional Chern insulators with originating from fractional fillings of the moiré lattice— , , and —associated with the formation of moiré-driven topological electronic crystals. At the system exhibits an integer quantum anomalous Hall effect at zero magnetic field, but further develops hints of an incipient fractional Chern insulator in a modest field. Our results establish moiré R5G as a fertile platform for studying the competition and potential intertwining of integer and fractional Chern insulators. Published by the American Physical Society2025
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Stability of anomalous Hall crystals in multilayer rhombohedral graphene
Recent experiments showing an integer quantum anomalous Hall effect in pentalayer rhombohedral graphene have been interpreted in terms of a valley-polarized interaction-induced Chern band. The resulting many-body state can be viewed as an anomalous Hall crystal (AHC), with a further coupling to a weak moiré potential. We explain the origin of the Chern band and the corresponding AHC in the pentalayer system. To describe the competition between AHC and Wigner crystal (WC) phases, we propose a simplified low-energy description that predicts the Hartree-Fock phase diagram to good accuracy. This theory can be fruitfully viewed as “superconducting ring” in momentum space, where the emergence of Chern number is analogous to the flux quantization in a Little-Parks experiment. We discuss the possible role of the moiré potential, and emphasize that even if in the moiréless limit, the AHC is not favored (beyond Hartree-Fock) over a correlated Fermi liquid, the moiré potential will push the system into a “moiré-enabled AHC”. We also suggest that there is a range of alignment angles between R5G and hBN where a 𝐶=2 insulator may be found at integer filling.
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- Award ID(s):
- 2206305
- PAR ID:
- 10650591
- Publisher / Repository:
- Physical Review B
- Date Published:
- Journal Name:
- Physical Review B
- Volume:
- 110
- Issue:
- 20
- ISSN:
- 2469-9950
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1103/PhysRevB.110.205130
