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

摘要

Thin YBCO films prepared by laser ablation froma nanocrystalline target have a high critical current density J_c?10~7 A cm~(-2) at 77K. To clarify the reason for the highvalue of J_c, the composition and structure of these films arecompared with those deposited from a typical coarse-grainedtarget. According to energy-dispersive x-ray and photoelectronspectroscopic analysis the contents of Y, Ba and Cu are similarin the films of both origins, despite some differences in thecompositions of the targets. It is concluded that the high value ofJ_c in the films prepared from the nanocrystalline target can beexplained by pinning of magnetic flux vortices to extended structural defects.