▎ 摘　　要

Based on the mean-field Hubbard model (J. Guo et al., Appl. Phys. Lett. 92, 163109 (2008)), ballistic spin transport in zigzag graphene nanoribbons is investigated theoretically. A giant magnetoresistance effect is found with 100% change in resistance as the two transverse electrodes switch from the parallel to antiparallel magnetic configuration. Such change is shown to arise from different coupling between the subbands near the Fermi level, which is dependent of the orbital symmetry. In addition, the operating energy window of giant magnetoresistance exists in a wide range of ribbon widths, easing the way for experimental validation of the proposed device. (C) 2011 American Institute of Physics. [doi:10.1063/1.3619817]