An all-field-range description of the critical current density in superconducting YBCOfilms

Abstract

A new critical current density (Jc) model forhigh-quality YBCO (YBa2Cu3O7) thin films has been proposed, combining thermally activated flux creep with a vortex pinningpotential for columnar defects. The pinning for thermally activated vortices has been describedas strong pinning on chains of individual edge dislocations that form low-angle domainboundaries in high-quality YBCO thin films. The model yields an adequate description of theJc behaviour over the whole applied field range, as verified by direct measurements ofJc in YBCO thin films grown by pulsed-laser deposition. It also indicates that theeffective pinning landscape changes under the influence of the external conditions.Remarkably, the pinning potential obtained from the model is consistent with the valuesobtained for columnar defects, which confirms the validity of the overall approach.