Critical current fluctuations in disordered superconducting wire networks

We report results of an investigation of magnetic-field dependent critical currents in artificially disordered superconducting Al wire networks well below T-c. Aperiodic but reproducible variations with field are found, in sharp contrast with the periodic oscillations observed close to T-c. Critical currents also exhibited strong variations on cycling the current at low fields reflecting variations in frozen-in metastable vortex patterns. Both the variations in field and on cycling vanished above a critical field set by the disorder strength.