Spin Fluctuation Depressed Superconductivity in Nb‐V Alloys

Abstract

Abstract The electrical resistivity of Nb‐V alloys has been measured around 250°C. Together with published values of the susceptibility and the electronic part of the specific heat the contribution of spin fluctuations t o the depression of the superconducting transition temperature, T c has been estimated. A calculation of T c based on experimental resistivity, susceptibility, and specific heat and with one adjustable parameter shows qualitative agreement with the observed T c over the whole alloy system and reasonable quantitative agreement in the dilute B V region. Further evidence for the existence of spin fluctuations in Nb‐V and an enhanced electron‐phonon coupling constant γ in V is derived from the observed rate of depression of T c with V concentration, published band structure calculations for V, and published Knight shift relaxation times.