Year: 2026
Type: preprint
Abstract: The experimental observation of the fractional quantum anomalous Hall effect in rhombohedral graphene multilayers has raised questions about the nature of the fractional Chern insulator (FCI) states and the role of the moiré potential. In this Letter we develop a composite fermion (CF) description and discuss how moiré modulation and Coulomb interactions stabilize the FCI ground states. Under a flux-attachment transformation and mean-field approximation, the CF spectrum forms Landau levels that are further split by the moiré potential. At moiré filling fractions in the Jain sequence, an integer number of CF bands are occupied, resulting in an incompressible ground state with fractionally quantized Hall response. Remarkably, when the attached flux opposes the Berry curvature of the conduction band of rhombohedral graphene, the CF Landau levels are widely spaced in energy and delocalized across layers, leading to a reduced density of states that helps protect the CF mean-field state and amplifying effects of the moiré potential acting on the layer away from the doped electrons. Interactions between CFs further enlarge the moiré-induced band gap and stabilize the FCI ground state. Our work sheds light on the nature of the FCI states in rhombohedral graphene and provides a new theoretical framework for further studies.
Source: arXiv (Cornell University)
Authors: Ding, Peize, Millis, Andrew J., Zeng, Yongxin
Institutions: Columbia University, Flatiron Institute, Yale University
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, U.S. Department of Energy, Yale University, Flatiron Health, Office of Science, Materials Research Science and Engineering Center, Harvard University, Division of Materials Research, Basic Energy Sciences, Air Force Office of Scientific Research, Energy Frontier Research Centers
OpenAlex ID: W7220982417