Spin-polarized transport in a coupled-double-quantum-dot system with ferromagneticelectrodes

Abstract

Based on the Keldysh non-equilibrium Green function method, the spin-polarized transportproperties in a coupled-double-quantum-dot (CDQD) system with ferromagnetic electrodes(FM–CDQD–FM) are investigated. It is clearly seen that, in contrast to the steplike orbasin-like behaviors of the spin (electrical) current in the FM–QD–FM system (Mu et al 2006 Phys. Rev. B 73 054414), the resonant tunneling determines the main features of thespin (electrical) current in the FM–CDQD–FM system. It must originate from the couplingeffect between two dots, which destroys the Coulomb blockade (CB) effect and makeselectron spin transport mainly depend on the cotunneling. Furthermore, it is alsofound that spin-polarized transport in the system is evidently modulated by thecoupling strength between two dots, which results from the non-equilibrium spinaccumulation and the spin precession for the presence of ferromagnetic electrodes.