Strong flux-pinning in epitaxial NdBa₂Cu₃O _7-δ films with columnar defects comprised of self-assembled nanodots of BaZrO₃

Epitaxial NdBa₂Cu₃O_7-δ (NdBCO) films with and without the incorporation of self-assembled nanodots of BaZrO₃ (BZO) were grown on rolling-assisted-biaxially-textured substrates (RABiTS) by pulsed laser deposition. Compared to epitaxial YBa ₂Cu₃O_7-δ (YBCO) films on RABiTS, NdBCO films are found to have superior performance in applied fields at all field orientations, suggesting the presence of an increased density of pinning centres. The incorporation of columns of self-assembled nanodots of BZO within the NdBCO films results in further enhancement of the in-field J_c at all field orientations. J_c varies as J_c∼H ^-α at intermediate fields, with α values for NdBCO and BZO-doped NdBCO films being ∼0.37 and ∼0.43, respectively, which are significantly lower than α∼0.52 for YBCO film.