▎ 摘　　要

We investigate the tunneling transport across a graphene p-n junction under the influence of a perpendicular magnetic field (B field). We observe a sideway deflection of the transmission profile, which can be quantitatively explained by invoking the classical Lorentz force. By considering the trajectory of the Dirac fermions along their cyclotron orbits, we analytically derive the incident angles for transmission across the graphene junction under a B field, as well as the critical magnetic field for full suppression of tunneling across the junction. These analytical predictions are consistent with the numerical results obtained via the non-equilibrium Green's function method. A stronger B-field conductance modulation is obtained for a p-n as opposed to an n-n or p-p type graphene junction. The magnetic field also induces a forbidden region of almost zero transmission for electron energy close to the Dirac point, which can be utilized to achieve a giant magnetoresistance effect. Based on our analysis, we devise an optimal magneto-electrical transport modulation, which can potentially realize a giant magnetoresistance effect in graphene p-n junction systems. (C) 2014 AIP Publishing LLC.