Effect of antiferromagnetic spin fluctuations on superconductivity

The effect of antiferromagnetic spin fluctuations on the superconducting transition temperature is discussed for the weak-coupling BCS model. The paramagnon-mediated depairing interaction μsub(s) and the mass enhancement due to paramagnons lambda sub(s) near the antiferromagnetic instability (α=1) are given as a function of α by μsub(s)(α) = lambda sub(s)(α) = xi - eta(1-α) sup(1/2) (α = Ix0(Q), I is the electron-electron interaction, x0(Q) the staggered susceptibility for I=0, xi and eta constants). It is shown that the paramagnon effect is considerable on the BCS transition temperature as it is on the linear specific heat coefficient in the normal state. Semi-quantitative analysis is made for CrMo alloys. (auth.)