Electronic states and magnetotransport in unipolar and bipolar graphene ribbons

The electronic structure and the current profiles of n- and p-doped graphene ribbons are investigated within the Keldysh-Green's function method in the tight-binding framework. The low energy spectrum, at the heart of the relativisticlike quantum transport, is studied numerically and relevant features are understood analytically by means of the continued fraction tool. Simulations of charge transport and spatial distribution of spectral currents in field-effect controlled graphene ribbons are then carried out in the absence and in the presence of uniform magnetic fields. The role of gated regions and threading magnetic fields for manipulating the flow of Dirac particles is investigated.