Spin diffusion in the double-exchange model far above the Curie temperature

A double-exchange model for studying spin diffusion in itinerant systems was presented. Spin relaxation in the itinerant system occurred while the electronic spin current left a region of the magnetic disturbance and the outgoing electronic polarization relaxed by coupling with the randomized spins outside the region. Analysis showed that for intermediate and finite temperature ranges, the integral over spin conductivity was proportional to the average kinetic energy and inversely proportional to the magnetic susceptibility. The double exchange model was suggested to be a good starting point for describing spin diffusion in manganites.