Three ranges of the angular dependence of critical current of BaZrO₃ doped YBa₂Cu₃O_7−δ thin films grown at different temperatures

The growth of BaZrO₃ (BZO) in pulsed laser deposited YBa₂Cu₃O_7−δ (YBCO) thin films was studied by varying the deposition temperature. It was found that there are three deposition temperature ranges based on the properties of J_c(θ), the angular dependence of critical current density. Samples made at a relatively low temperature (low-T samples) do not show a c-axis peak in J_c(θ) whereas mid-T samples exhibit a peak as B∥c-axis of YBCO. In high-T samples the c-peak disappears again. In the low-T samples BZO rods are too splayed and short for a c-axis peak whereas in the high-T samples vortices move along correlated, but shortened rods as well as along stacking faults, which causes the c-axis peak to disappear. The superconducting properties of the films were studied with both magnetic and transport measurements and the structural properties were characterized using X-ray diffraction and transmission electron microscopy. Correlations between the structural and superconducting properties were analyzed using the vortex path model. - Highlights: • Growth temperature (T_dep) dependent pinning structure in YBa₂Cu₃O_7−δ is revealed. • Three different regimes of T_dep related to BaZrO₃ pinning structure are found. • A c-axis peak in angular dependence of critical current density J_c at certain T_dep. • The theoretical vortex path model explains the behavior of angular dependence of J_c. • The model is in good agreement with structural properties