Magnetic Fingerprints in Superconducting Au_(0.7)In_(0.3) Cylinders

Reproducible, sample-specific magnetoresistance fluctuations (magnetic fingerprints) were observed in the low-temperature part of the superconducting transition regime of hollow Au$_{0.7}$In$_{0.3}$ cylinders of submicron diameter. The amplitude of the fluctuations was found to exceed that of the universal conductance fluctuation in normal metals by several orders of magnitude. The physical origin of these observations is related to mesoscopic fluctuations of the superconducting order parameter.