Magnetic-field-induced pair-breaking effects in granular Pb films near the superconductor-to-insulator transition

We have measured the magnetic-field dependence, 0{≤}H{≤}8 T, of the resistive transitions R(T) of ultrathin granular superconducting Pb films with normal-state sheet resistances, RQ{≤}RN{≤}100 k{Ω}, where RQ=h/4e²{}6.45 k{Ω}. The data suggest that the magnetic-field-induced superconductor-to-insulator transition in these films occurs in a field regime where pair-breaking effects have significantly reduced the amplitude of the superconducting order parameter. We compare our results with those obtained on systems with uniform morphologies.