Critical current anisotropy and pinning in (103)YBCO superconducting thin films on SrTiO3(110) substrates

Abstract

High quality (103) oriented YBCO superconducting thin films with T-c approximate to 89 K have been prepared by pulsed laser deposition on SrTiO3 (110) substrates. The grain morphology of the films, as revealed by both scanning electron microscopy and atomic force microscopy, shows distinct brick wall structure. The critical current densities measured along (001) direction of the substrates are about an order of magnitude higher than that measured on the other in-plane direction with no apparent weak-link behavior observed. The critical current densities in both directions, however, show a similar linear temperature dependence over a wide temperature range, indicative of a flux-creep limited mechanism. The creep rate in both cases, as fit to the Anderson-Kim creep model, is of order of 1 which is about an order of magnitude higher than that of conventional type-II superconductors. Samples co-ablated with silver were also studied. Detail mechanisms of pinning as wall as grain morphology evolutions are discussed.