Researchers use graphene-like photonic crystal to demonstrate fourth edge state

Graphene and graphene-like materials can host—at their edges—localized states whose properties can differ dramatically from those of bulk states. Three types of edge states have been established in these materials—zigzag, bearded, and armchair—named after their geometry. Now, researchers from Nankai University and Shanxi University used a graphene-like photonic crystal to demonstrate the possibility of a fourth edge, called twig, with exotic topological features. Their results may broaden the understanding of graphene edge states, as well as open new avenues for realization of robust edge localization and nontrivial topological phases based on Dirac-like materials.