Flat bands in bilayer graphene induced by proximity with polar $h$-BN superlattices

TL;DR

This study demonstrates how proximity to polarization superlattices in twisted h-BN multilayers can induce flat bands in bilayer graphene, offering a new way to engineer electronic properties at the atomic scale.

Contribution

The paper introduces a combined first-principles and tight-binding approach to show flat-band formation in bilayer graphene influenced by h-BN superlattices, extending beyond continuum models.

Findings

Flat bands can be induced in bilayer graphene via h-BN superlattices.

Band structures depend on local inversion symmetry breaking.

Flat-band manifolds appear at superlattice periodicities above ~30 nm.

Abstract

Motivated by the observation of polarization superlattices in twisted multilayers of hexagonal boron nitride ($h$-BN), we address the possibility of using these heterostructures for tailoring the properties of multilayer graphene by means of the electrostatic proximity effect. By using the combination of first-principles and large-scale tight-binding model calculations coupled via the Wannier function approach, we demonstrate the possibility of creating a sequence of well-separated flat-band manifolds in AB-stacked bilayer graphene at experimentally relevant superlattice periodicities above $\sim$30 nm. Our calculations show that the details of band structures depend on the local inversion symmetry breaking and the vertical electrical polarization, which are directly related to the atomic arrangement. The results advance the atomistic characterization of graphene-based systems in a superlattice potential beyond the continuum model.