RESISTIVITY-PEAK ANOMALY IN YUBA2CU3O7-DELTA CRYSTALS AND NONUNIFORMLY DISTRIBUTED CRITICAL-TEMPERATURE INHOMOGENEITIES

We report the observation of a sharp peak (20% of the normal resistivi ty), just above the superconducting transition, in the curve of the ab -plane electrical resistivity versus temperature of some nonfully oxyg enated YBa2Cu3O7-delta crystals, with transition temperatures below 90 K. This resistivity anomaly may easily be explained by assuming the p resence of critical temperature inhomogeneities associated with small stoichiometric (oxygen content) inhomogeneities, at long length scales , nonuniformly distributed in the crystals. Our findings directly appl y to the resistivity, the thermopower, and the Hall effect behavior in other superconducting materials having nonuniformly distributed T(c) inhomogeneities.