▎ 摘　　要

By employing a self-consistent approach, we reveal a number of unique properties of zigzag graphene nanoribbons under crossed electric and magnetic fields: (1) a very strong electrical polarization along the transverse direction of the ribbon, and (2) a strong nonlinear Hall current under a rather moderate electrical field. At the field strength of 5000 V/cm, the ratio of the nonlinear current to the linear current is around 1 under an applied magnetic field of 7.9 T. Our results suggest that graphene nanoribbons are an ideal system to achieve a large electrical polarizability. Our results also suggest that the nonlinear effect in graphene nanoribbons has been grossly underestimated without the self-consistent scheme proposed here. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3647783]