Abstract
V-I curves of several Y-Ba-Cu-O samples have been measured in the temperature range 77–91 K in weak magnetic fields (H<150 Oe). For the well prepared low-resistivity samples ==dV/dI reaches a value of about 0.1 ( is the normal resistance just above transition) in the linear V-I regime. This is consistent with a picture of decoupled superconducting grains and does not yield any direct information about the flux-flow effects. Because of self-field effects, critical-current density () obtained from transport (and magnetization) measurements does not provide clear insight on the nature of intergrain coupling. Information on the distribution of critical currents, obtained from V/, supports the tunneling and/or proximity-effect coupling between the grains and seems to rule out large enhancements of in sintered samples with nonoriented grains.
- Received 23 October 1989
DOI:https://doi.org/10.1103/PhysRevB.41.6278
©1990 American Physical Society