Evaluation of out-of-plane coeherence length of (103)/(013) YBCO films from electrical transport measurements

The out-of-plane plane coherence length xi c of YBa2Cu3O7-delta superconductor has been evaluated by analysing the thermally activated magnetic vortex flux creep across superconducting CuO2 layers. Current flow along CuO2 layers has been ensured by patterning (103)/(013) oriented films into several macro-bridges positioned at different angles with respect to the crystalline planes. The bridge in which vortex creep occurs across the intrinsic potential Of CuO2 layers has been selected on the basis of the superconducting transition and current-voltage characteristics. Current-voltage characteristics of the selected bridge were analysed in the framework of the theoretical model of Barone et al (1990 J. Supercond. 3 155), which accounts for a vortex creep in a periodic potential. The estimated out-of-plane coherence length, ranges between 0.11 and 0.30 nm for films with different oxygen and structural defect contents, consistently with values evaluated with different techniques and reported in the literature. The xi c value changes in different ways with changing critical temperature T-c depending on the dominating type of oxygen vacancies and defects.