Self-organized artificial pinning structure in small-scale YBCO films grown on an advanced IBAD-MgO based template

For applying high-temperature superconductors (HTS) in electrical applications, such as many electrical power systems, single crystalline substrates can not be used as they lack flexibility. Using coated conductors with the metallic tape-based template is the necessity to overcome such deficiencies. However, how these structures would pin the magnetic vortices and thus positively affect the superconducting properties especially in high external magnetic field range, is not easy to implement with coated conductors and therefore we have concentrated on small-scale thin films. In this work, the films of YBa3CuO6+x (YBCO) doped with non-superconducting BaCeO3 (BCO) and BaZrO3 (BZO) phases were deposited separately on C276 IBAD-MgO based buffered metallic tapes by using pulsed laser deposition method. As mobile vortices cause resistance in superconductors, doping was done to pin them into artificially created defects besides naturally available defects. Two sets of films, one BCO doped YBCO and another BZO doped YBCO, producing isotropic randomly distributed particles and correlated columnar defects, respectively, were prepared at temperatures ranging from 650 °C – 800 °C. Structural, microstructural, magnetic and transport properties were measured by X-ray diffractometer (XRD), atomic force microscope (AFM) and Quantum Design physical property measurement system (PPMS) respectively. We have mainly focused on angular dependent measurements because of their significance in application of superconducting wires. Several temperature and field ranges were used during transport measurements, in order to get a reliable picture where different dopants are optimally distributed. As a conclusion of this work, the films prepared at 750 ℃ showed the best superconducting properties in both BCO and BZO doped YBCO films grown on the buffered metallic substrates. On the other hand, the films prepared at 750 °C also revealed highest critical current densities in wide magnetic fields and angular (0 ° to 360 °) ranges. In addition, the angular dependent critical current properties show significant difference in vortex pinning anisotropy, which again is an extremely important factor when optimizing these materials for future electric power systems