A Detailed Study of Anisotropic Critical Currents in Ba sub 2 YCu sub 3 O sub 7 Single Crystals.

We have extended Bean's critical state model to include explicitly anisotropic critical currents. Measurements at 30K of the critical currents parallel to the Cu-O planes but with vortex motion either parallel or across twin boundaries shows twin boundaries are not an important cause of vortex pinning. In the critical state current flow perpendicular to the Cu-O planes is about 30 times smaller than flow parallel to these planes.