Theory of the self-diffusion (spin diffusion) coefficient of an electron gas

Abstract

The self-diffusion (spin-diffusion) coefficient D of an electron gas is investigated by means of a proper connected diagram expansion which treats a collision in a medium (rather than in vacuum) in a natural manner. By calculating real and virtual interaction processes to the order e 4 (second order in interaction strength), we obtain D = 0.3597 ℏ 1 2 e -2(k BT) 5 4 n 0 -1 2 M -3 4 for a non-degenerate gas where n 0 represents the density. The square-root density ( n 0) dependence is noteworthy. In the calculation, no cut-off limiting low momentum transfer in collision is introduced; the screening effect which is important at higher densities, is neglected.