Field behavior of the critical current in quasi-single-crystalline YBCO films

Magnetic field, angular and temperature dependencies of the critical current density were measured by SQUID-magnetometry, ac magnetic susceptibility, and transport techniques in single-crystalline epitaxial YBCO films. The mechanism of vortex depinning from growth-induced linear defects consistently quantitatively describes the measured Jc(H)-dependencies. The model takes into account a distribution of domain size as well as the dislocation spacing within domain boundaries. Structure parameters of YBCO films extracted from Jc(H parallel c,T)-curves and X-ray diffraction studies agree