Superconducting fluctuations in the destructive regime of ultrathin, superconducting cylinders

We have carried out experiments on ultrathin superconducting cylinders, which revealed the existence of a destructive regime predicted to occur around half-integer flux quanta in doubly connected samples with diameters smaller than the zero-temperature superconducting coherence length. At half-integer flux quanta, the resistance showed a broad resistance drop as the temperature was lowered, followed by a temperature independent resistance at the lowest temperatures. We show that the temperature dependence of the conductance at half-integer flux quanta can be attributed to superconducting fluctuations.