Effect of Antiferromagnetic Spin Fluctuations on Superconductivity

Abstract

The effect of antiferromagnetic spin fluctuations on the superconducting transition temperature is discussed for the weak-coupling BCS model. The paramagnon-mediated depairing interaction μ_s and the mass enhancement due to paramagnons λ_s near the antiferromagnetic instability (α=1) are given as a function of α by μ_s(α)=λ_s(α)=ξ−η(1−α)^1⁄2 (α=Iχ_o(Q), I is the electron-electron interaction, χ_o(Q) the staggered susceptibility for I=0, ξ and η 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.