Spatially Resolved Characterization of the Local Superconducting Properties of Compositional Gradient REBCO Films

We have succeeded in developing a high-resolution and high-throughput measurement method for local sheet current density (J_s) and critical temperature (T_c) in a thin film sample prepared by Transient Liquid-Assisted Growth using Chemical Solution Deposition (TLAG-CSD), based on magnetic microscopy. Drop-on-demand inkjet printing (IJP) has been adopted to design and fabricate a combinatorial sample with a one-dimensional compositional gradient of Rare Earth (RE) elements within the REBa₂Cu₃O_7-δ (REBCO, RE = Y_ϵGd_1-ϵ) crystal. The quality of the epitaxial REBCO film has been assessed in several sample locations by means of EDX, XRD and SEM characterization techniques to unravel the Rare Earth influence on the growth. However, the relationship with superconducting properties is not yet fully understood. In this study, we have developed a high-resolution and high-throughput measurement method for local J_s at low temperature and in-field conditions, as well as T_c in a film sample by low-temperature in-field scanning Hall probe microscopy. Corresponding J_s distributions are obtained at 5 K and up to 4.5 T, which J_s is greatly influenced by the composition because the Gd rich compositions exhibit polycrystallinity and ab-oriented grain. The optimum compositions for the highest J_s are close to the 50% of Y and Gd composition at 4.5 T and at self-field. Furthermore, the temperature dependence of J_s distribution is studied up to 88.0 K at self-field and the spatial T_c distribution is derived to study the relationship between T_c and compositions. T_c dependence with the Rare Earth composition is similarly to that of J_s.