Thermokinetic approach of the generalized Landau-Lifshitz-Gilbert equation with spin polarized current

Abstract

In order to describe the recently observed effect of current induced magnetization reversal in magnetic nanostructures, the thermokinetic theory is applied to a metallic ferromagnet in contact with a reservoir of spin polarized conduction electrons. The spin flip relaxation of the conduction electrons is described thermodynamically as a chemical reaction. The diffusion equation of the chemical potential (or the giant magnetoresistance) and the usual Landau-Lifshitz-Gilbert (LLG) equation are derived from the entropy variation. The expression of the conservation laws of the magnetic moments, including spin dependent scattering processes, leads then to the generalized LLG equation with spin polarized current. The equation is applied to the measurements obtained on single magnetic Ni nanowires.