Critical current anomaly in superconducting proximity-effect bridges

The current-voltage characteristics of long Ag-Sn proximity-effect bridges obtained at helium bath temperature (T) close to the lambda-point of helium (Tsub(lambda)) show an abnormal jump in the critical current (Isub(c)) at T=Tsub(lambda)). It is observed that Isub(c)sup(2/3) varies linearly with T which is similar to what has been reported by previous workers, but the slope changes at T=Tsub(lambda). The implications of the observed phenomena are examined. (Auth.)