Importance of spin fluctuations for the thermodynamic properties of superconducting V and VN

Solving Eliashberg's equation on the imaginary $\omega$ axis, we calculate thermodynamic properties of superconducting V and VN including the influence of spin fluctuations within the theory of Berk and Schrieffer. We find that, besides the specific-heat coefficient $\gamma$, which is already known to be changed by spin fluctuations, the thermodynamic critical field $H_c\mathrm{}\left(0\right)\mathrm{}$ and the specific-heat jump $\Delta C$ are also strongly affected in both superconductors. For VN, we predict substantial increases of $H_c\mathrm{}\left(0\right)\mathrm{}$ and $\Delta C$ above those values which would be obtained without consideration of spin fluctuations. Therefore, specific-heat measurements on stoichiometric samples of VN could establish the importance of these effects.