Fresh from the Oven

Abstract --- We discuss the generation of a spin current by an edge plasmon in a graphene ribbon, which is a kind of surface plasmon that is localized near the edges of the ribbon. In contrast with a surface plasmon on the surface of a three-dimensional metal, the electric field of the edge plasmon rotates as a function of the time in the plane of graphene, which means that the optical spin-angular momentum of the edge plasmon is out of plane. We found that the electric-field-induced spin current flows by the inverse Faraday effect between the edges of the ribbon with spin polarization of electrons in the out-of-plane direction. The symmetric mode of the edge plasmon gives a larger magnitude of the spin current than the antisymmetric mode does. Moreover, the magnitude and direction of the spin current are tunable not only by the frequency of the edge plasmon, but also by the Fermi energy of graphene, which enables application to a spin-switching device controlled by a gate voltage.