Hybrid classical-quantum models for charge transport in graphene with sharp potentials

We give a concise account on the derivation of hybrid quantum-classical models for stationary electron transport in graphene, in presence of sharp potential steps of barriers. A quantum region (an asymptotically thin strip around the potential step or barrier) is coupled through the quantum scattering data to a classical region, where electron transport is described in terms of semiclassical kinetic equations. The diffusive limit of the kinetic model is derived by means of the Chapman-Enskog method, which requires the introduction of a boundary layer corrector and the discussion of a system of coupled Milne problems.