Specific features of inverse exchange current switching in ferromagnetic nanojunctions

The theory of exchange current switching in ferromagnetic nanojunctions is developed. Included in a junction are two contacting layers: a layer with fixed lattice magnetization and a free layer. The theory takes into account two concurrent effects induced by a polarized current in the junction: (1) transfer of transverse spins from the current carriers directly to the magnetic lattice and (2) injection of longitudinal spins into the free layer and the subsequent generation of a nonequilibrium sd-exchange field. A vector condition that requires continuity of the total spin flux of the electrons and the lattice is applied at the layer boundaries. The equation of motion that meets the vector boundary condition is derived for the magnetization values. The obtained solution exhibits specific features characteristic of inverse switching: Switching occurs when electrons are moving in an efficient injection field and, at the same time, involves transfer of torque to the lattice.[PUBLICATION ABSTRACT]