Structural and flux-pinning properties of laser ablated YBa2Cu3O7-δ thin films: Effects of self-assembled CeO2 nanodots on LaAlO3 substrates

Self-assembled nanodots of CeO2 on (100) LaAlO3 substrates, generated in situ by means of a pulsed laser deposition method prior to the deposition of YBa2Cu3O7-delta (YBCO) films, have been used to modify the superconducting properties of resulting YBCO films. Structural characterization has indicated that CeO2 layers grow via van der Merwe three-dimensional mode and the islands eventually acquire a pancake type of structure with lateral dimension several times larger than vertical dimension. The three-dimensional growth of CeO2 islands with (100) preferred orientation is believed to be associated with its surface energy anisotropy. The magnetization versus temperature and magnetization versus field measurements and analysis have suggested that CeO2 can affect the superconducting properties of YBCO films favorably or adversely depending on the density of CeO2 nanodots on the substrate surfaces prior to the deposition of YBCO films. (C) 2008 Elsevier B.V. All rights reserved.