DETERMINATION OF THE CRITICAL CURRENT-DENSITY IN SUPERCONDUCTING FILMS - COMPARISON OF A MEASURED MAGNETIC-FLUX DISTRIBUTION WITH MODEL-CALCULATIONS

We have investigated the magnetic field distribution of an epitaxial YBa2Cu3O7-x film and compared the result with a theoretical calculation which has recently been proposed. This model takes into account the strong demagnetization effects that occur if a thin superconducting film is exposed to an external magnetic field perpendicular to the sample plane. It describes the magnetic field distribution of a two-dimensional current distribution under the assumption that there are two opposing current bands, both carrying the critical current density j(c). We use j(c) as a fit parameter and find very good agreement between the measured and the calculated field distributions.