Observation of anomalous low-field magnetoresistance in a mesoscopic Al loop near the superconducting transition

We have observed anomalous low-magnetic-field resistance oscillations in a mesoscopic Al loop slightly above the superconducting transition temperature Tc. We interpret the anomaly as a consequence of a combined field dependence of the enhanced superconductivity at the nodes of the voltage probes and of the normal-electron coherence-effect oscillations in the loop itself. (orig.)