Who: Alessando de Martino (City Univeristy of London)
Place: Donostia International Physics Center
Date: Tuesday, 12 September 2017, 12:00
In the last few years, the ballistic transport regime has become routinely accessible in high-quality graphene devices. This development has generated a renewed interest in the transport properties of graphene pn junctions. In this talk, I will present a theoretical study of the interface states which form near pn junctions in a graphene monolayer subject to a perpendicular magnetic field. I will discuss the exact and essentially analytical solution of the quantum-mechanical eigenproblem for both a straight and a disc-shaped junction. In both cases, the spectrum consists of localized Landau-like and unidirectional propagating interface states. The semiclassical limit of these states corresponds to trajectories propagating along the pn interface by a combined skipping-snaking motion. For a straight junction, the group velocity of the chiral mode originating from the zeroth Landau level interpolates as function of the potential step height between the classical drift velocity in a crossed electromagnetic field and the semiclassical value expected for a purely snaking motion. Away from the Dirac point, the chiral interface states resemble the conventional skipping orbits found also in the corresponding Schro?dinger problem. In the case of a circular geometry, the chiral interface states are predicted to carry sizeable circulating currents.