Edges and interactions for graphene in quantum Hall states

We study the electronic structure near a graphene edge in a strong perpendicular magnetic field. In high Landau levels these edge states are similar in structure to those of standard two-dimensional electron gas systems (s-2DEG's). The lowest Landau supports half as many edge states as those of higher Landau levels, leading to a quantization of the Hall conductance that is shifted relative to s-2DEG's. The presence of both hole-like and electron-like edge states is shown to lead to the existence of a domain wall at the edge of an undoped graphene armchair edge when one considers the effect of quantum Hall ferromagnetism. The domain wall supports both collective and charged gapless excitations whose consequences for tunnelling experiments are discussed. (c) 2007 Elsevier Ltd. All rights reserved.