Topological Flat Bands in Graphene Super-moir\'e Lattices

TL;DR

This paper theoretically demonstrates that a monolayer graphene placed between two twisted boron nitride layers can host topological ultra-flat bands, providing a simple platform for exploring topological flat band physics.

Contribution

It introduces a novel method to realize topological flat bands in graphene using a double-boron nitride moiré superlattice with specific twist angles.

Findings

Topological ultra-flat bands emerge from the second hole band in the proposed setup.

The system provides a simple platform for designing and studying topological flat bands.

Potential for exploring correlated and topological phenomena in graphene-based heterostructures.

Abstract

Moir\'e-pattern based potential engineering has become an important way to explore exotic physics in a variety of two-dimensional condensed matter systems. While these potentials have induced correlated phenomena in almost all commonly studied 2D materials, monolayer graphene has remained an exception. We demonstrate theoretically that a single layer of graphene, when placed between two bulk boron nitride crystal substrates with the appropriate twist angles can support a robust topological ultra-flat band emerging from the second hole band. This is one of the simplest platforms to design and exploit topological flat bands.