A study of the volt-ampere characteristics of S-c-N contacts based on the amorphous superconductor Zr2Ni

The volt-ampere characteristics of S-c-N contacts between Zr2Ni and a normal metal (Cu and Ag) were measured as the temperature was decreased below the critical temperature of 2.5 K. The volt-ampere characteristic became increasingly nonlinear as the temperature was lowered or as the contact resistance decreased. In the latter case, a singularity of the voltage discontinuity type was observed for a certain critical current value. The observed singularity is attributed to the generation of Abrikosov vortices and transition of the contact to the resistive state.