Model of spin transport in noncollinear magnetic systems: Effect of diffuse interfaces

We propose a theoretical model to study the spin transport, particularly the interfacial resistance in a noncollinear system with a diffuse interface. The realistic interface region arising from the sputtering process is first modeled by using Fick's law. Subsequently, the spin transport behavior in magnetic system is determined via a generalized spin accumulation model taking into account spin dephasing term. Our model is able to deal with magnetic systems with arbitrary orientation of magnetization by employing the transfer matrix approach. The model is first used to investigate spin accumulation in a bilayer system consisting of a ferromagnet (FM) and a non-magnet (NM). The influence of important transport parameters: spin dephasing, interdiffusion, injected current density and spin polarization on magnetoresistance (MR) are studied. Next we investigate the transport properties of a FM/NM/FM system where the interface disorder giving rise to enhanced spin dephasing is modeled. We found that the interdiffusion of the FM/NM/FM interface gives rise to large spin scattering, which enhances the GMR. The results also show that including the disorder arising from interface diffusion is an important contribution to the transport properties.