Composite fermions in ideal Chern bands

Abstract

The composite-fermion framework maps the strongly correlated fractional quantum Hall state onto a weakly interacting integer quantum Hall state in a reduced effective magnetic field. We ask how this framework is modified for fractional Chern insulators, where the role of a uniform magnetic field is replaced by the nonuniform Berry curvature of a Chern band. Specifically, we construct composite-fermion wave functions for Jain states and their quasiparticles and quasiholes in Aharonov-Casher bands, a widely used model for ideal Chern bands. We find that these states overlap closely with exact eigenstates over a broad range of field modulation. Using these wave functions, we demonstrate that the emergent composite-fermion band structure goes beyond the conventional picture of effective Landau levels, correctly capturing the quasiparticle dispersion. Remarkably, we find that an isolated quasiparticle band carries a total Berry flux that is different from a Landau level. These results establish a composite-fermion description for mobile fractional Chern insulator anyons and provide a framework to understand their stability.