Scattering of normal excitations by superconducting fluctuations in single-crystal and granular copper oxide superconductors

By using a unified empirical procedure, the intrinsic paraconductivity in the ab plane, Δ${\mathrm{\sigma }}^{\mathit{i}}$, is extracted from different available data for resistivity rounding in single-crystal and granular ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$ samples, and from data in ${\mathrm{Bi}}_{1.5}$ ${\mathrm{Pb}}_{0.5}$ ${\mathrm{Sr}}_2$ ${\mathrm{Ca}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{\mathit{y}}$ granular samples. These results strongly suggest that both high-temperature superconductor systems will have relatively strong pair-breaking effects, and that Δ${\mathrm{\sigma }}^{\mathit{i}}$ may be explained by direct superconducting order-parameter-fluctuation effects alone.