Spin-valve effect in zigzag graphene nanoribbons by defect engineering

We report on the possibility for a spin-valve effect driven by edge defect engineering of zigzag graphene nanoribbons. Based on a mean-field spin-unrestricted Hubbard model, electronic band structures and conductance profiles are derived, using a self-consistent scheme to include gate-induced charge density. The use of an external gate is found to trigger a semiconductor-metal transition in clean zigzag graphene nanoribbons, whereas it yields a closure of the spin-split band gap in the presence of Klein edge defects. These features could be exploited to make charge- and spin-based switches and field-effect devices.