Berry phase in graphene: Semiclassical perspective

We derive a semiclassical expression for the Green’s function in graphene, in which the presence of a semiclassical phase is made apparent. The relationship between this semiclassical phase and the adiabatic Berry phase, usually referred to in this context, is discussed. These phases coincide for the perfectly linear Dirac dispersion relation. They differ, however, when a gap is opened at the Dirac point. We furthermore present several applications of our semiclassical formalism. In particular, we provide, for various configurations, a semiclassical derivation of the electron’s Landau levels, illustrating the role of the semiclassical “Berry-like” phase.