Single buffer layer technology for YBCO coated conductors

In an effort to develop alternative single buffer layer technology for YBa₂Cu₃O_7-δ (YBCO) coated conductors, we have investigated LaMnO₃ (LMO) as a potential buffer layer. High-quality LMO films were grown directly on biaxially textured Ni and Ni-W (3%) substrates using rf magnetron sputtering. YBCO films were then grown on LMO buffers using pulsed laser deposition. Detailed X-ray studies have shown that both YBCO and LMO layers were grown with a single epitaxial orientation. Rutherford backscattering spectroscopy (RBS) analyses have indicated the ratio of La to Mn ratio is 1:1. SEM micrographs indicated that 3000-Å-thick LMO films on biaxially textured Ni (100) substrates were dense, continuous and crack-free. A high J_c of over 1 MA/cm² at 77 K and self-field was obtained on YBCO films grown on LMO-buffered Ni or Ni-W substrates. We have identified LaMnO₃ as a good diffusion barrier layer for Ni and it also provides a good template for growing high current density YBCO films.