Effect of radiation defects and implanted ions on the superconducting properties of vanadium films

The change in the critical parameters of superconducting vanadium films under irradiation with helium ions is studied. It is found that implanted inert gas impurities and radiation defects have the same effect on the critical temperature T/sub c/ and the upper critical field H/sub c/2 of vanadium. The decrease in T/sub c/ is due to a change in the characteristics of the electronic spectrum of vanadium due to disordering. The irradiation-induced increase in H/sub c/2 is explained qualitatively and quantitatively by the theory of type II superconductors. A small change in the critical parameters, due to the proximity effect, is also observed when a thin surface layer of the films, which is small compared to the film thickness, is irradiated