LITTLE-PARKS OSCILLATIONS OF TC IN PATTERNED MICROSTRUCTURES OF THE OXIDE SUPERCONDUCTOR YBA2CU3O7 - EXPERIMENTAL LIMITS ON FRACTIONAL-STATISTICS-PARTICLE THEORIES

We report observation of Little-Parks oscillations in arrays with a 4-m2 plaquette area, fabricated from -axis-oriented YBa2Cu3O7 films. Near the mean-field transition temperature the magnitude of the oscillations implies a zero-temperature coherence length (0)=152 A. For temperatures more than 1 K below the mean-field transition, the magnitude of the oscillations increases dramatically, apparently signaling a crossover to the dynamics of a Josephson-coupled network. Precise experimental limits can be placed on the value of the flux quantum, severely restricting any anomalous value which may be proposed on the basis of fractional-statistics-particle theories. © 1990 The American Physical Society.