Optimizing superlattice bilayer graphene for a fractional Chern insulator

TL;DR

This paper investigates how to optimize superlattice parameters in bilayer graphene to realize stable fractional Chern insulators by analyzing band structures and quantum geometry.

Contribution

It provides a detailed calculation of band structures and quantum geometry for bilayer graphene under various superlattices, identifying optimal conditions for FCI stability.

Findings

Optimal parameter regimes for FCI stability identified

Band structure and quantum geometry characterized across superlattice types

Guidelines provided for experimental realization of FCIs in bilayer graphene

Abstract

Bernal-stacked bilayer graphene modulated by a superlattice potential is a highly tunable system predicted to realize isolated topological flat bands. In this work we calculate the band structure and quantum geometry of bilayer graphene subject to both triangular and square superlattices, across a wide range of gate voltages. We identify the parameter regime that optimizes the "single-particle indicators" for the stability of a fractional Chern insulator (FCI) when a topological flat band is partially filled. Our results guide the experimental realization of an FCI in this platform.