DISCONTINUITY LINES IN RECTANGULAR SUPERCONDUCTORS WITH INTRINSIC AND EXTRINSIC ANISOTROPIES

Magneto-optical investigations of the flux distributions in the critical state of a {ital c}-axis-oriented square YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} thin film with an extrinsic anisotropy induced by an in-plane magnetic field are presented. The dependence of the anisotropy ratio of the critical currents on the orientation of the in-plane field with respect to the direction of current flow is determined. The results are compared with flux distributions in a rectangular DyBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} single crystal with a microstructural anisotropy induced by the introduction of oblique linear defects. For the intrinsic anisotropy the flux is found to penetrate parallel to the inclination direction of the pins even if the flux motion is then not parallel to the Lorentz force exerted by the shielding currents. The angular distribution of the critical currents in general is different from the elliptic distribution, which was found for the extrinsic anisotropy.