Angular dependence of irreversibility field in Y-123 coated tape

It is known that the critical current density vs. field angle of an Y-123 coated tape has a broad peak around the field direction normal to the tape surface. In this work, the angular dependencies of the irreversibility field and the critical current density are analytically investigated using the flux creep-flow theory with an assumption of the angular dependence of flux pinning strength, and these results are compared with the experimental results. The angular dependence of flux pinning strength obtained so as to get a good agreement between the experimental and theoretical results suggests an existence of long pinning centers along the c-axis.