Controllable Spin Polarization of Charge Current by Rashba Spin Orbital Coupling

We report a theoretic study on modulating the spin polarization of charge current in a mesoscopic four-terminal device of cross structure by using the inverse spin hall effect. The scattering region of device is a two-dimensional electron gas (2DEG) with Rashba spin orbital interaction (RSOI), one of lead is ferromagnetic metal and other three leads are spin-degenerate normal metals. By using Landauer-Buttiker formalism, we found that when a longitudinal charge current flows through 2DEG scattering region from FM lead by external bias, the transverse current can be either a pure spin current or full-polarized charge current due to the combined effect of spin hall effect and its inverse process, and the polarization of this transverse current can be easily controlled by several device parameters such as the Fermi energy, ferromagnetic magnetization, and the RSOI constant. Our method may pave a new way to control the spin polarization of a charge current.