Flux-pinning mechanisms in thin films of YBa2Cu3Ox.

Abstract

We consider data from several experiments taken at very small induction in order to discern the nature of the pinning interaction in some thin-film samples of ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{\mathit{x}}$ with very large critical current densities. Analysis of typical pinning energies and critical current densities indicate that the pinning is due to a large density of point defects. We propose a simple model of pinning by point defects in the ${\mathrm{CuO}}_{2}$ planes that predicts a spacing between defects of 53 \AA{}. This large defect density may help to explain other properties of these films.