Improving the Flux Pinning With Artificial BCO Nanodots and Correlated Dislocations in YBCO Films Grown on IBAD-MgO Based Template
To improve the performance of high-temperature superconductors in electrical power systems, a modified IBAD-MgO based template is used as a substrate for the growth of YBa<inline-formula><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula>Cu<inline-formula><tex-math notation="LaTeX">$_{3}$</tex-math></inline-formula>O<inline-formula><tex-math notation="LaTeX">$_{6+x}$</tex-math></inline-formula>(YBCO) doped with various concentrations of BaCeO<inline-formula><tex-math notation="LaTeX">$_{3}$</tex-math></inline-formula>(BCO). The highest critical current density (<inline-formula><tex-math notation="LaTeX">$J_\mathrm{c}$</tex-math></inline-formula>) in a wide applied field and angular range is realized in the films doped with 2<inline-formula><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> and 4<inline-formula><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> BCO content. This is explained to arise from the optimized BCO dopant concentration, which helps to immobilize more vortices both in low and high field ranges. Besides the vortex pinning by randomly distributed BCO nanoparticles, the edge-type dislocations, mainly occurring due to the underlying IBAD-MgO based template, are also a main source of pinning the vortices as seen by the appearance of <inline-formula><tex-math notation="LaTeX">$c$</tex-math></inline-formula>-axis peak of <inline-formula><tex-math notation="LaTeX">$J_\mathrm{c} (\theta)$</tex-math></inline-formula> in undoped and 2<inline-formula><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> doped films. The disappearance of c-peak in films doped with higher concentration can be qualitatively explained by the vortex path model, where the paths of the vortices arising because of high density of BCO particles disguise the columnar type pinning effect coming from the threading dislocations within the films. Therefore, the BCO nanodots can be used for improving the flux pinning besides the threading dislocations in YBCO films on metal substrates.