Electronic states of graphene grain boundaries

Recent scanning tunneling spectroscopy measurements on graphite grain boundaries have identified zero energy peaks in the local density of states. These features are tied to intriguing magnetic properties observed in such samples, but are not found in existing theoretical models. We therefore study amorphous grain boundaries in graphene, and find stable structures along the boundary, responsible for local density of states enhancements both at zero and finite energies. We also consider the low energy continuum theory of arrays of dislocations forming a grain boundary in graphene. It predicts the appearance of localized zero energy states, pending the atomic scale dislocation core structure. We discuss possible stable dislocation core structures that actually carry such states.