How to transfer spins from the electric current to the ferromagnetic degree of freedom?

Abstract

We present the last developments of the approach of spin-transfer in terms of mesoscopic non-equilibrium thermodynamics. The modification of the ferromagnetic states due to the presence of a spin-accumulation process is investigated. The spin accumulation (also responsible for giant magnetoresistance) is generated by an electric current at the interfaces with a ferromagnetic nanostructure. The dynamical coupling that links the ferromagnetic degree of freedom to the spin of the conduction electrons is investigated with taking into account longitudinal and transverse spin accumulation. It seems that the coupling with the transverse spin-accumulation may be equivalent to the usual spin-transfer-torque mechanisms deduced from microscopic transmission- reflection coefficients at the interface. In contrast, the coupling with the longitudinal spin- accumulation generates fluctuations and seems to play important role in the activation process at larger time scales only.