The incorporation of nanoscale columnar defects comprised of self-assembled BaZrO₃ nanodots to improve the flux pinning and critical current density of NdBa₂Cu₃O_7-δ films grown on RABiTS

We report significant enhancement in the flux-pinning of epitaxial NdBa₂Cu₃O_7-δ (NdBCO) films on rolling-assisted biaxially textured substrates (RABiTS) via the incorporation of a two-dimensional array of columnar defects comprised of self-assembled BaZrO₃ (BZO) nanodots. Pure NdBCO films and NdBCO films incorporating BZO nanodots, both with the same thickness of 0.6νm, were epitaxially grown on RABiTS by pulsed laser deposition. A very dense and homogeneous distribution of BZO nanodot columns with typical intercolumn spacing of around 15-20nm oriented along the c-axis of the film was observed in the NdBCO+BZO film. Compared to the pure NBCO film on RABiTS, the NdBCO+BZO film on RABiTS has an in-field critical current density (J_c) of a factor of more than 2 in 0.1-1.5T and a smaller power-law exponent α∼0.21 in the field regime where J_c∼H^-α.