Observation of Magnetic Fingerprints in Superconducting Au₀.7In₀.3 Cylinders

Reproducible, sample-specific magnetoresistance fluctuations (magnetic fingerprints) have been observed experimentally in the low-temperature part of the superconducting transition regime of disordered superconducting Au_0.7In_0.3 cylinders. The amplitude of the fluctuation 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 discussed in the context of mesoscopic fluctuations of the superconducting condensation energy in disordered superconductors.