Transport Property Improvement by Means of BZO Inclusions in PLD Grown YBCO Thin Films

A detailed study on YBa₂Cu₃O_7-delta (YBCO) films with BaZrO₃ (BZO) inclusions (YBCO-BZO) deposited on SrTiO₃ substrate with different BZO contents is presented. X ray diffraction, SEM imaging and superconductive critical temperature (T _c) measurements were performed to evaluate film growth quality. Independently from the BZO content, all YBCO-BZO films showed T _c values close to that of pure YBCO indicating that the T _c reduction which is usually observed on YBCO-BZO films can be successfully recovered by changing the deposition conditions. All YBCO-BZO films showed an improved critical current density (J _c) dependence on magnetic field if compared to the typical J _c(H) of YBCO, resulting in higher irreversibility fields up to 9 T at 77 K. SEM observation on etched samples suggests a direct link between the defect density measured in YBCO-BZO samples and that calculated from the observed in field performances. The analysis of J _c(B) as a function of applied magnetic field direction revealed that the pinning due to isotropic pinning centers typical for YBCO is coupled with a c-axis correlated pinning in YBCO-BZO which can be ascribed to BZO induced columnar defects. J _c (B) recorded at several temperatures down to 10 K revealed matching effect features.