MAGNETIC-FLUX PINNING IN EPITAXIAL YBA2CU3O7-DELTA THIN-FILMS

The influence of microstructure on the critical current density of las er ablated YBa2Cu3O70-delta thin films has been examined. Scanning tun neling microscopy was used to examine the morphologies of YBa2Cu3O7-de lta films and the morphology data were then correlated with measuremen ts of the critical current density. The films were found to grow by an island nucleation and growth mechanism. The critical current densitie s of the films are similar to those of films with screw dislocation gr owth, indicating that screw dislocation growth is not necessary for go od pinning. The data suggest that the critical current density in appl ied magnetic field may be higher in films with higher densities of gro wth features.