Electron-state tuning of multilayer graphene by defects

Electronic band structures of graphene thin films, in which the topmost layer possesses atomic and topological defects, are studied using the density functional theory. Our calculations showed that all graphene thin films studied here have a finite energy gap in their π electron states, although the thin films possess defect-free hexagonal networks, because of the spatially undulated local potential on pristine graphene layers induced by the defects. The energy gap in π states slightly decreases with increasing number of layers, while the gap sensitively depends on the interlayer stacking arrangement. Our analyses clarify that the interlayer interaction plays a crucial role for mediating the effect of the defects on the π electrons of pristine layers