EFFECTS OF THERMAL-PROCESSING AND OXYGEN COMPOSITION ON FLUX PINNING IN HIGH-JC EPITAXIAL Y1BA2CU3O7-X THIN-FILMS

High-J(c), c-axis epitaxial Y1Ba2Cu3O7-x thin films were produced by post-annealing of Y, BaF2, and Cu precursor films in wet oxygen. The films were reacted either at 835-degrees-C in 1 atm, or at 800-degrees-C in a low oxygen partial pressure p(O2); the chain-site oxygen deficiency x was subsequently varied by low temperature anneals below 550-degrees-C in various p(O2) less-than-or-equal-to 1 atm. All films showed a monotonic decrease in J(c) with increasing x, but exhibited a T(c)(x) that was dependent on the initial formation conditions. The effects are of electronic origin, and are consistent with a simple model of carrier density influence on near-optimal flux pinning.