Electronic zero modes of vortices in Hall states of gapped graphene

The recent observation of a metal-insulator phase transition in the nu = 0 Hall state of graphene has inspired the idea that charge carriers in the metallic state could be fractionally charged vortices. We examine the question of whether vortices in particular gapped states of graphene and subject to external magnetic and pseudomagnetic fields could have the midgap zero mode electron states which would allow them to be charged.