Influence of radiation-induced defects and implanted ions on the superconductive properties of vanadium films

The authors have studied the alteration of the critical parameters of superconducting vanadium films, subjected to irradiation by helium ions. It was found that implanted noble gas impurities and radiation-induced defects produce similar effects on the critical temperature Tsub(c) and the upper critical field Hsub(c2) of vanadium. Depression of Tsub(c) due to changes in characteristics of the V electronic spectrum caused by disordering. Increase of Hsub(c2) as a result of radiation is qualitatively and quantitatively explained in terms of the type 2 superconductor theory. A minor change in the critical parameters due to the proximity effect is also revealed in case of irradiation of the thin surface of the layer film which is small in comparison with the whole film thickness