Spin Fluctuation Depressed Superconductivity in Nb‐V Alloys

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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, Tc has been estimated. A calculation of Tc based on experimental resistivity, susceptibility, and specific heat and with one adjustable parameter shows qualitative agreement with the observed Tc 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 Tc with V concentration, published band structure calculations for V, and published Knight shift relaxation times.