1000 A cm⁻ ¹in a 2 µm thick YBa₂Cu₃O7 −xfilm with BaZrO₃and Y₂O₃additions

We report here on significant improvements to the in-field and self-field critical current densities ( J c ) of multilayer and single-layer YBa 2 Cu 3 O 7 − x (YBCO) thick films with BaZrO 3 (BZO) and Y 2 O 3 additions. In the former case, the composite film consisted of a five-layer architecture with three YBCO layers and two Y 2 O 3 interlayers in a total thickness of 1.8 µm. The multilayer film produced a J c (75.6 K, self-field) of 4.3 MA cm − 2 (775 A cm − 1 ) and a minimum J c (75.6 K, 1 T) of 1.0 MA cm − 2 (175 A cm − 1 ) over all field orientations in the maximum Lorentz force configuration. We achieved in a single-layer 2.0 µm thick film a J c (75.6 K, self-field) of 5.2 MA cm − 2 (1010 A/cm-w) and a minimum J c (75.6 K, 1 T) of 1.2 MA cm − 2 (234 A/cm-w) in the same measurement configuration. For both kinds of films, scanning transmission electron microscopy and transmission electron microscopy imaging were used to identify a uniformly dispersed second-phase microstructure consisting of short, tilted BZO nanorods and tilted Y 2 O 3 nanoparticle layers. We attribute the enhanced performance of the thick YBCO films to the uniformity of the microstructure and the interaction of two different second-phase materials during film growth.