上海科技大学知识管理系统

In this work, we theoretically study the fractional Chern insulator (FCI) states in rhombohedral multilayer graphene moiré superlattices. We start from the highest energy scale (∼2eV) of the continuum model, and construct a renormalized low-energy model that applies to a lower cutoff ∼0.15eV using a renormalization group approach. Then, we study the ground states of the renormalized low-energy model at filling 1 under the Hartree-Fock approximation in the presence of tunable but self-consistently screened displacement field D with several experimentally relevant background dielectric constants ϵr. Focusing on the pentalayer moiré graphene system, two competing Hartree-Fock states are obtained at filling 1, which give rise to two types of topologically distinct isolated flat bands with Chern numbers 1 and 0, respectively. By hole-doping the isolated topological flat bands, both Laughlin-type and composite-fermion-type FCI states can be obtained through exact-diagonalization calculations at different fractional filling factors, which exhibit quantitative consistency with experimental measurements. We further explore the correlated topological states in generic rhombohedral multilayer graphene moiré superlattices, and find that FCI states may also emerge in tetralayer and hexalayer moiré graphene systems. © 2024 American Physical Society.