Spin diffusion in the double-exchange model at intermediate temperatures

Using a combined numerical and analytic approach, we evaluate the spin-diffusion coefficient D for the double-exchange model in the limit t ≪ T ≪ J_H, where t is the hopping energy, T is the temperature, and J_H is the Hund's coupling. To lowest order, D ∝ tq(1 - 2q)/T χ where q is given in terms of the band filling p by either p(p < 1/2 ) or 1 - p(p > 1/2 ). Hence, the spin-diffusion coefficient vanishes when the electrons are unable to hop between singly-occupied sites in a half-filled (p = 1/2 ) band.