Pore formation and increased critical current density in YBa2Cu3Ox films deposited on a substrate surface modulated by Y2O3 nanoparticles

YBa2Cu3O7−x (YBCO) films of thicknesses from 0.1 to 0.6 µm were grown on a 20 nm base layer of Y2O3 particles. The particles typically have dimensions of ∼140 nm (radial) by ∼26 nm, and provide an isotropically modulated surface morphology on which the YBCO films are deposited. It was observed that the surface morphology of the YBCO film grown on the particles resembles the highly porous structure seen previously in vicinal YBCO films deposited on anisotropically modulated miscut SrTiO3 substrates. Magnetic measurements also showed similarly enhanced critical current densities Jc as observed in the vicinal films. The results provide a critical confirmation of strain-induced pore formation and improved Jc by pore surface pinning.

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