Topological Flat Minibands and Fractional Chern Insulators in Rashba Systems with Tunable Superlattice Potentials

TL;DR

This paper introduces a tunable platform using Rashba systems with superlattice potentials to create flat topological minibands that support fractional Chern insulators, offering a new route for experimental exploration of correlated topological phases.

Contribution

It demonstrates a method to engineer topological flat minibands with Chern number one in Rashba systems using tunable superlattice potentials, supporting fractional Chern insulators.

Findings

Isolated flat miniband with Chern number 1 achieved

Fractional Chern insulators at 1/3 and 2/3 filling demonstrated

Realistic material candidates identified for experimental realization

Abstract

We propose a programmable platform for engineering topological flat minibands by imposing a tunable electrostatic superlattice potential on a Rashba spin-orbit-coupled thin film subject to a Zeeman field. The interplay between the superlattice potential and Zeeman coupling produces an isolated flat miniband with Chern number $\mathcal{C}=1$. Using many-body exact diagonalization, we show that this miniband supports fractional Chern insulators at filling factors $n = 1/3$ and $2/3$, both of which remain robust over broad parameter ranges. We further identify realistic material candidates and the corresponding device conditions that enable experimental realization. These results establish a versatile and experimentally accessible platform for engineering topological flat minibands and exploring correlated topological phases.