ORDER-PARAMETER DIMENSIONALITY, RESISTIVITY AND TRANSITION-TEMPERATURE IN PURE AND ZINC-DOPED YBA2CU3O7-Y THIN-FILMS

In pure and 0.33% Zn doped (at Cu-site) c-axis oriented laser ablated epitaxial thin films of YBa2Cu3O7-y superconductors the excess conduct ivity, order parameter dimensionality (delta) and the effects of their variation on dimensionality cross-over have been studied. Relative to the dimensionality crossover in pure film the Zn doped film shows fas t suppression of superconductivity fluctuations. Comparison with other studies indicates: (1) high mean field critical temperature (T-c(mf)) does not necessarily imply that rho(T) will be less; (2) for pure fil ms, crossover correlates more with rho(T) than T-c(mf) (3) in Zn doped sample order parameter dimensionality delta has an uncertain correlat ion with rho(T), but the pure films have an inverse variation; (4) in pure and Zn doped samples delta is directly proportional to T-c(mf). T hese suggest inverse correlation between T-c(mf) and resistivity in th e pristine system, which is absent in the case of Zn doped sample.