▎ 摘　　要

The magnetoresistance (MR) of Co/multilayer graphene/Co spin valve structures has been studied. A positive MR of up to 0.39% at 2 K with switching at magnetic fields that are consistent with the magnetization orientations inferred from anisotropic MR data obtained for the Co contacts has been observed. The positive MR decreases with increasing excitation current and eventually changes sign. The positive MR decreases with increasing temperature, but the negative MR has no temperature dependence. (c) 2007 American Institute of Physics.