▎ 摘　　要

We imposed screwing operation to a metallic ferromagnetic zigzag-edged graphene nanoribbon (ZGNR) with a narrow width and a finite length, and the polarized charge transport is investigated by using Nonequilibrium Green's function in combination with density functional theory. The current are nearly completely suppressed when the ZGNRs are overturned. Inspiringly, this metal-to-semiconductor transition tuned by screwing operation is reversible. Hence our investigation brings forward a novel electromechanical switch, and such a switch is equivalent to a spill valve without resort to an external magnetic field. (C) 2012 Elsevier B.V. All rights reserved.