▎ 摘　　要

Sign-changeable spin-filter efficiency is predicted in both the ferromagnetic and antiferromagnetic configurations of a zigzag graphene nanoribbon bridging two half-planar graphene electrodes from ab initio quantum transport calculations. By changing edge spin-polarization configuration, we obtain giant room-temperature magnetoresistance, which is one order of magnitude larger than the maximum experimental results. (C) 2011 Elsevier B.V. All rights reserved.