Influence of the anisotropy in the c-axis resistivity measurements of high- Tc superconductors

Abstract

The cross-measurement configuration, commonly used in the determination of the c-axis resistivity was the matter of our theoretical analysis. We obtained an analytical expression for the measured resistivity which depends on a `effective anisotropy' factor, identified here as Γ, and takes into account the non-homogeneous current distribution into the sample. We showed that the best experimental results are obtained for superconductor samples with the largest Γ. In particular, for samples with Γ>1, the distance between the voltage contacts and the current ones should be a third of the length of the sample in order to obtain the real ρ c and to avoid the use of other complicated experimental set-up.