Transport times and conductivity in graphene in the presence of random electric and magnetic fields

We calculate the conductivity tensor for a deformed graphene sheet, in the presence of an external in plane magnetic field and random neutral and charged impurities. We use the semiclassical Boltzmann transport equation to find the transport times due to each scattering mechanism. For random scalar potentials (isotropic scattering) both backward and forward scattering are suppressed. This suppression of backscattering can be understood as a consequence of the overlap between incoming and outgoing states. However, we explicitly show that for random magnetic field (anisotropic scattering) the overlap between states has a hidden angular dependency that actually favours backward scattering and only forward scattering is suppressed, like in conventional two dimensional electron gas (2DEG). This opens the possibility for weak localisation without inter valley scattering in graphene.