Characteristics of ErBa2Cu3O7−δ films with BaWO4 doping

Abstract

BaWO4 (BWO) doped ErBa2Cu3O7−δ (Er-123) (BWO+Er-123) films are fabricated and their superconducting properties are evaluated. We discuss the effect of BWO doping into Er-123 films on their crystallinity and superconducting properties. The grown BWO+Er-123 films were in-plane aligned and c-axis oriented. We characterize in-plane crystallinity of the films by XRD in-plane rotation measurement (φ-scan). The full width at a half maximum of the φ-scan pattern (δφ) of the grown BWO+Er-123 films became wider as increasing BWO doping. The critical temperature (TC0) of 2.0wt% BWO+Er-123 films was about 90.5K. From this result, it was confirmed that the BWO+Er-123 films had as high TC as pure Er-123 films. Surface resistance (RS) of the BWO+Er-123 films was degraded comparing to that of a pure Er-123 film. The relationships between critical current density (JC) and applied magnetic field (JC–B) and the magnetic field angular dependence of JC of the grown 2.0wt% BWO+Er-123 film were evaluated at 77K. As a result, it is confirmed that the JC of the Er-123 films in magnetic fields decreased by the BWO doping comparing to that of the pure Er-123 film. However, it was also confirmed that the 2.0wt% BWO+Er-123 film had weak pining centers along the c-axis of Er-123 films. From the result of a cross-sectional transmission electron microscope (TEM) image, some rod structures were observed in the 2.0wt% BWO+Er-123 films. The diameter of the rod was about 20nm. These rods grew along the c-axis of Er-123 films from the substrate to the surface of the film.