In-plane field-effect correction in quantitative magneto-optical analysis

We present a detailed analysis of the calibration procedure to be performed in order to extract from magneto-optical images the local values of magnetic induction and electric current density on a plane over and. inside the superconducting sample respectively. The interaction between the spontaneous magnetization of the indicator film and the full magnetic field distribution in the specimen region has been considered. In particular, the generally disregarded interaction of the indicator film with in-plane magnetic fields, that is with the component parallel to the indicator surface, is retained in the model. The current density distribution is obtained by the numerical inversion of the Biot-Savart law. In order to incorporate the in-plane field effect into the inversion scheme, we have constructed an iterative procedure which successfully takes into account the full magnetic induction field. A set of experimental data on a high-temperature superconducting YBa2Cu3O7-x, film is presented to show the actual impact of the new analysis method, for what concerns both the local values of the magnetic induction and the electrical current density evaluation.