Local photo-excitation of spin current generation in a one-dimensional system

Abstract

We investigate the dynamics of spin current generation in a one-dimensional system under light illumination by using the time-dependent nonequilibrium Green’s function formalism. To demonstrate the mechanism of spin current generation, we first consider a spinless system with an asymmetric on-site potential. Thus, the system under light irradiating exhibits a DC particle current, which is an odd function of the parameter to characterize the asymmetric potential. Based on that, we design a model, in which the asymmetric potential experienced by the spin-up electrons is opposite to that for the spin-down electrons. Consequently, the DC polarized currents from the spin-up electrons and from the spin-down ones may travel along opposite directions, and thus a pure DC spin current is realized. The spin current as a function of the light frequency is also discussed briefly. These results could be useful for the design of spin devices based on electronic materials.