Flat bands by latent symmetry

Abstract

The geometry of a lattice may cause energy eigenstates to localize compactly by destructive interference, resulting in flat energy bands. This effect is often induced by symmetry. A ``latent'' symmetry, inspired from graph theory, is a hidden permutation symmetry revealed upon reduction of the original system onto a subsystem; here, an effective two-site dimer. Combined with collective symmetries between possible pathways connecting the dimer sites to special site subsets in the lattice unit cell, latent symmetry provides a novel systematic way to explore and construct flat bands.

Topics & Concepts