FIELD-INDUCED RESISTIVITY IN CRYSTALLINE YBA2CU3O7-DELTA - EVIDENCE FOR NANO-SCALE JUNCTION STRUCTURES

We have carried out a series of measurements of the resistivity of a high quality single crystal of Y-Ba-Cu-O, near the superconducting transition temperature, as a function of field varying to a maximum of 5 T applied in the a-b plane of the crystal. The results of the measurements are described accurately in terms of a model for phase-slip resistivity given by Tinkham which features phase-slip dissipation in small Josephson junctions. Since this is a crystal, the junctions are not present as a consequence of grain boundaries, but are believed to be a consequence of defects in oxygen (vacancy) ordering in the charge reservoir layers. As a result, the junctions are believed to be intrinsic to the material. The defects which give rise to the junctions are likely candidates for intrinsic pinning centers. This model is compared to a vortex-liquid state model discussed by Chien et al. © 1993 Academic Press. All rights reserved.