▎ 摘　　要

We investigate the electron transport through a graphene nanoribbon (GNR) junction with zigzag edges. It is shown that the edge state and the magnetization properties of a GNR greatly influence its electron transport properties. By applying sufficient back-gate voltages to the lead parts of a zigzag GNR, the magnetization of the edges is quenched in the leadings parts, but is preserved in the center part of the junction. Without applying external transverse electric field, we show that, by preparing the junction in a ferromagnetic state, a strongly spin-polarized electron current can be obtained even though the incident electron current has no spin polarization.