Normal state properties of high angle grain boundaries in (Y,Ca)Ba2Cu3O7-delta

TL;DR

This study investigates the normal state electrical properties of high-angle grain boundaries in (Y,Ca)Ba2Cu3O7-delta superconductors, revealing how doping, oxygen content, and misorientation affect charge transport barriers.

Contribution

It provides detailed measurements of grain boundary resistance and conductance, linking these properties to structural and compositional factors in high-angle grain boundaries.

Findings

Grain boundary resistance varies with temperature and voltage.

Doping and oxygen content influence the potential barrier height.

Charge transport occurs through a tunnel barrier model.

Abstract

By lithographically fabricating an optimised Wheatstone bridge geometry, we have been able to make accurate measurements of the resistance of grain boundaries in Y1-xCaxBa2Cu3O7-d between the superconducting transition temperature, Tc, and room temperature. Below Tc the normal state properties were assessed by applying sufficiently high currents. The behaviour of the grain boundary resistance versus temperature and of the conductance versus voltage are discussed in the framework charge transport through a tunnel barrier. The influence of misorientation angle, oxygen content, and calcium doping on the normal state properties is related to changes of the height and shape of the grain boundary potential barrier.