Critical currents of superconducting aluminium - germanium and lead - germanium thin film alloys near the metal - insulator transition

The critical currents of Al-Ge and Pb-Ge thin film alloys have been measured as a function of the metal volume fraction x. They have been found to vary as (x - xc)v where xc is the value of x at the metal-insulator transition. This behaviour is similar to that of the conductances σ of the same samples in the normal state. We interpret these results in terms of current percolation theories.