Interplay between structural anisotropy and order parameter symmetry effects in transport properties of YBa Cu O grain boundary Josephson junctions

Abstract:

We have designed an experiment that could allow to investigate, on the same sample, the interplay between the morphological anisotropy of high critical temperature superconductors and the effects related to the order parameter symmetry. To this aim we have employed c-axis tilt biepitaxial grain boundary YBa₂Cu₃O _{7 - δ} Josephson junctions and measured the junction properties for different junction interface orientations. The results give evidence of the possibility to tune normal state resistance and critical current density of a Josephson junction almost independently of each other. We interpret the results of this experiment as an indication that Cooper pairs and quasi-particles transport properties may be ruled by different mechanisms. Measurements apparently give evidence of the possibility to determine to some extent the presence of “π-loops” and “0” loops along the same grain boundary line.