Current-density inhomogeneity throughout the thickness of superconducting films and its effect on their irreversible magnetic properties

We calculate the distribution of the current density (Formula presented) in superconducting films along the direction of an external field applied perpendicular to the film plane. Our analysis reveals that in the presence of bulk pinning (Formula presented) is inhomogeneous on a length scale of the order of the intervortex distance. This inhomogeneity is significantly enhanced in the presence of surface pinning. We introduce a critical state model, which takes into account the current-density variations throughout the film thickness, and show how these variations give rise to the experimentally observed thickness dependence of (Formula presented) and magnetic relaxation rate.