Resistance oscillations and magnetic fingerprints in superconducting Au0.7In0.3 cylinders - art. no. 144521

Magnetoresistance of hollow Au0.7In0.3 cylinders of submicron diameter was measured in the superconducting transition regime. Depending on the amount of disorder present in the samples, resistance oscillations were either abs ent or found only below a certain temperature in the transition regime. For those samples where the resistance oscillations were completely suppressed , reproducible sample-specific magnetoresistance fluctuations (magnetic fin gerprints) were observed, also in the low-temperature part of the transitio n regime. The amplitude of the conductance fluctuation exceeded that of the universal conductance fluctuation in normal metals by several orders of ma gnitude. The fluctuation disappeared as superconductivity in the samples wa s suppressed by increasing either temperature or magnetic field. Thermal cy cling to temperatures much higher than the superconducting critical tempera ture resulted in irreversible changes in the fingerprint pattern. In additi on, a negative magnetoresistance was found just above the transition temper ature in some samples. The physical origin of these observations is discuss ed in the context of mesoscopic effects in disordered superconductors.