MAGNETIC FIELD DEPENDENCE OF THE ULTRASONIC ATTENUATION AND RESISTANCE OF A SUPERCONDUCTING GRANULAR LEAD FILM

Abstract

We report on the measurements of the ultrasonic attenuation and the d.c. resistance of a superconducting granular lead film as a function of both temperature and applied magnetic field. In the absence of an applied magnetic field, the d.c. resistance and ultrasonic attenuation can be accounted for, qualitatively, by using percolation theory. When a magnetic field is applied, we find that if we assume that both the ultra-sonic attenuation and the resistivity are proportional to the effective area through which the field penetrates the film, we can deduce magnetization curves for the film from the normalized attenuation and resistance data. The shapes of these magnetization curves are consistent with those of a type II superconductor.