Evidence of vortex curvature and anisotropic pinning in superconducting films by quantitative magneto-optics

We present the experimental observation of magnetic field line curvature at the surface of a superconducting film by local quantitative magneto-optics. In addition to the knowledge of the full induction field at the superconductor surface yielding to the quantitative observation of the flux line curvature, our analysis method also allows local value measurements of the electrical current density inside the sample. Thus, we study the interplay between the electrodynamical constraints dictated by the film geometry and the pinning properties of the superconductor. In particular, we investigate the anisotropic vortex pinning, due to columnar defects introduced by heavy ion irradiation, as revealed in the local current density dependence on the vortex curvature during magnetic flux diffusion inside the superconducting film.