Fluctuation conductivity in unconventional superconductors near critical disorder

The fluctuation conductivity σ_S in bulk superconductors with non s-wave pairing and with nonmagnetic disorder of strength D is studied at low T and within the Gaussian approximation. It is shown by assuming a quasi two-dimensional (2D) electronic state that, only if the gap function d_μ (p) is, as in a 2D p-wave pairing state, linear in the in-plane (relative) momentum p_⊥, the in-plane fluctuation conductivity on the line D = D_c is weakly divergent in low T limit. The present result may be useful in clarifying the true gap function of spin-triplet Sr₂RuO₄ through resistivity measurements.