LOW-FIELD MAGNETORESISTANCE IN GRANULAR PB FILMS NEAR THE INSULATOR-SUPERCONDUCTOR TRANSITION

We have studied the insulator-superconductor transition in quench-condensed granular Pb films from 0.1 to 10 K. Resistance measurements were made in zero magnetic field and low noise conditions. Magnetoresistance measurements were also performed for low magnetic fields (less than 100 G). The magnetoresistance results on the superconducting side of the transition suggest that we are directly probing the finite length scales associated with the range of phase coherence in these granular materials.