Reason for high critical current in thin YBCO films prepared by laser ablation from nanostructured target

Thin YBCO films prepared by laser ablation from a nanocrystalline target have a high critical current density Jc approx.= 107 A cm-2 at 77 K. To clarify the reason for the high value of Jc, the composition and structure of these films are compared with those deposited from a typical coarse-grained target. According to energy-dispersive x-ray and photoelectron spectroscopic analysis the contents of Y, Ba and Cu are similar in the films of both origins, despite some differences in the compositions of the targets. It is concluded that the high value of Jc in the films prepared from the nanocrystalline target can be explained by pinning of magnetic flux vortices to extended structural defects. (author)