Speaker
Description
Designed band engineering via perturbative superlattice potentials, inspired by graphene on hexagonal boron nitride substrate, potentially allows to induce topological bands. Making use of the general form of a substrate potential as dictated by symmetry, we derive the low-energy mini-bands of an hexagonal superstructure. Assuming a large supercell, we focus on a single Dirac cone (or valley) and find all possible arrangements of the low-energy electron- and hole bands in a complete six-dimensional parameter space. We identify the sectors hosting topological mini bands and also characteris complex band crossings that generate a Valley Chern number atypically larger than one. Our map provides a starting point for the systematic design of topological bands by substrate engineering.