Moving domain walls by spin-polarized current

A phenomenological model is proposed for magnetic junction consisting of two ferromagnetic layers (electrodes) separated by a nonmagnetic ultrathin layer (spacer). One of the electrodes has a magnetization pinned parallel to interfaces and the other one is free and may contain magnetic domain structure. Electrical current flows through the spacer from the pinned layer to free one and it can effect on the free layer magnetic state due to spin injection. Current-dependent energy of s-d exchange interaction between injected carriers and localized spins is calculated. From the condition that a total magnetic energy of the junction is to be minimal, the domain structure period and the relative width of preferential domains are found as functions of an external magnetic field and the spin-polarized current. With increasing in the current, the preferential domains grow due to moving the domain walls. A possibility is shown of magnetic saturation and magnetization reversal in the free layer by a current of ∼10⁵ A/cm².