Substrate Surface Decoration With CeO2 Nanoparticles: An Effective Method for Improving Flux Pinning in YBa2Cu3O

We have demonstrated improved critical current density, J_c, in YBa₂Cu₃O_7-delta (YBCO) films through a controlled study of substrate surface modifications with nano-sized second-phase pre-formed CeO₂ particles. Nanoparticles were applied to single crystal SrTiO₃ surfaces using suspension-based techniques prior to YBCO film growth. With the introduction of CeO₂ nanoparticles, YBCO films showed more robust field dependence at intermediate fields (J_c prop B^-prop), where a smaller power law exponent of alpha ~ 0.3 is obtained. The self-flefd J_c(77K, Bparc) values of the YBCO films on reference and CeO₂ modified substrates are 1.1 and 1.9 MA/cm² ; and at 1 Tesla 0.1 and 0.52 MA/cm² , respectively. Consistent with this alpha-value, angular field dependent J_c and transmission electron microscopy studies indicate the presence of c-axis aligned correlated defects in these modified samples.