Conduction electron spin relaxation in the superconducting state

By considering the way in which various interactions that flip the spin transform under time reversal, the BCS coherence factors that are associated with the spin-flip matrix element of these interactions are determined. For spin-orbit scattering by non-magnetic impurities the temperature dependence of the relaxation rate below Tsub(c) is calculated and compared with the experimental results on niobium reported in the preceding paper. (orig.)