Influence of oxygen deficiency on anisotropy and -axis critical current densities in single crystals

Abstract

The coupling between the layers has been studied in a series of six single crystals, together with a and a crystal, in terms of the magnetically measured interlayer critical current. The Ginzburg-Landau thermodynamic anisotropies have been estimated too. As oxygen is removed, the coupling weakens and both and the anisotropy between inter- and intralayer critical current densities, , increases rapidly. The current anisotropy appears to be larger than , and increases as the temperature is reduced, whereas should be temperature independent. These results are discussed in terms of Abrikosov versus Josephson vortices, and their effective dimensionality; possible pinning mechanisms are considered.