Transport Properties of the New High T sub c Superconductive Oxide Films

A general description of the electrical properties of thin films, bulk ceramics and crystals of mainly YBa sub 2 Cu sub 3 O sub 7, both below and above T sub c, will be presented in this talk. Because of anisotropy, transport and superconductivity is dominated by currents flowing in the a-b basal plane of the orthorhombic structure. The observation that the temperature dependence of the resistivity p||(T) in linear in temperature implies that electron-phonon coupling is too weak to explain the high T sub c. Analysis of high-temperature resistivity data is used to study effects of changes in oxygen stoichiometry: oxygen intercollation/desorption rates, electron scattering by oxygen-vacancy defects, the orthorhombic-to-tetragonal phase transition, the metal-semiconductor transition.