Abstract
Technological applications of high temperature superconductors (HTS) require high
critical current density, Jc, under operation at high magnetic field strengths. This requires
effective flux pinning by introducing artificial defects through creative processing.
In this work, we evaluated the feasibility of mixed-phase LaMnO3:MgO (LMO:MgO)
films as a potential cap buffer layer for the epitaxial growth and enhanced performance
of YBa2Cu3O7-d (YBCO) films. Such composite films were sputter deposited directly on
IBAD-MgO templates (with no additional homo-epitaxial MgO layer) and revealed the
formation of two phase-separated, but at the same time vertically aligned, self-assembled
composite nanostructures that extend throughout the entire thickness of the film. The
YBCO coatings deposited on these nanostructured cap layers showed correlated c-axis
pinning and improved in-field Jc performance compared to those of YBCO films
fabricated on standard LMO buffers. Microstructural characterization revealed additional
extended disorder in the YBCO matrix. The present results demonstrate the feasibility
of novel and potentially practical approaches in the pursuit of more efficient, economical,
and high performance superconducting devices.
