Estudo dos efeitos de pressão hidrostática nas propriedades elétricas do supercondutor Y1-xCaxBa2Cu3O7-δ

Abstract

In this work we report the results of a study about the pressure effects on the electrical properties of Ca doped YBa2Cu3O7. Temperature dependent in-plane resistivity measurements were carried out on Y1-xCaxBa2Cu3O7-δ single crystals with x = 0, 0.01, 0.05, 0.10. Hydrostatic pressure conditions P < 15 kbar were generated in a Cu-Be piston-cylinder pressure cell specially developed for this purpose. Our results indicate that substitution of Ca2+ in the Y3+ site and application of hydrostatic pressures both affect the normal and superconducting properties. From the analysis of the contribution of superconducting fluctuations to the conductivity we identified a fluctuation regime described by the small exponent Tcr = 0.20 ± 0.01 in a narrow temperature range immediately above Tc(P). The origin of this fluctuation regime is still unclear. A possibility is that it may be a precursor to a weakly first-order pairing transition. Our results indicate the role played by Ca doping in the stabilization of this super-critical regime.