Dirac fermion confinement in graphene

We study the problem of Dirac fermion confinement in graphene in the presence of a perpendicular magnetic field B. We show, analytically and numerically, that confinement leads to anomalies in the electronic spectrum and to a magnetic-field-dependent crossover from √B, characteristic of Dirac-Landau-level behavior, to linear-in-B behavior, characteristic of confinement. This crossover occurs when the radius of the Landau level becomes of the order of the width of the system. As a result, we show that the Shubnikov--de Haas oscillations also change as a function of field, and lead to a singular Landau plot.