Magnetic flux pinning in epitaxial YBa2Cu3O7−δ thin films

The influence of microstructure on the critical current density of laser ablated YBa₂Cu₃O_7−δ thin films has been examined. Scanning tunneling microscopy was used to examine the morphologies of YBa₂Cu₃O_7−δ films and the morphology data were then correlated with measurements of the critical current density. The films were found to grow by an island nucleation and growth mechanism. The critical current densities of the films are similar to those of films with screw dislocation growth, indicating that screw dislocation growth is not necessary for good pinning. The data suggest that the critical current density in applied magnetic field may be higher in films with higher densities of growth features.