Superconducting properties ofVNxsputtered films including spin fluctuations and radiation damage of stoichiometric VN

We have made well-ordered, stoichiometric films of VN using reactive sputtering and studied the effects of disordering due to deviations from stoichiometry and radiation damage. An unexpected local minimum of $T_c$ for the well-ordered, stoichiometric VN was found. The principal result was that the peak in $T_c$ for substoichiometric ${\mathrm{VN}}_{0.96}$ can be shown to be consistent with a competition between spin fluctuations and electron–phonon coupling, but we find the effect of the former is smaller than previously predicted. The superconducting properties measured in radiation-damaged VN have been extrapolated to pure, stoichiometric VN.