Magneto-optical analysis is a powerful tool to analyse local magnetic field distribution across superconducting and magnetic materials. We present a careful procedure of non-linear calibration for quantitative evaluation of the local magnetic field in superconducting and magnetic materials. In particular the in-plane field distribution must be carefully taken into account to avoid under-estimation of the out of plane component [1,2,3]. The experimental results concern imaging of different superconducting and magnetic materials ranging from low temperature superconductors to magnetic superconducting heterostructures. In particular we present a detailed imaging of a YBa₂Cu₃O₇/La_0.7Sr_0.3MnO₃/LaAlO₃ multilayer. The substrate exhibits a tri-crystal twinned structure. At the tri-crystal centre point substrates twins meet each other in three different directions: the developed magnetic domains exhibit the expected annihilation on twins due to opposite in-plane orientation of the magnetization and form out-of-plane domain-walls. After cooling below YBCO critical temperature, vortices are nucleated over out-of-plane magnetic domain-walls. Following their own stray-field orientation they nicely decorate such magnetic domain-walls.

The italian members of the working group acknowledge the contributions of the Istituto Nazionale per la Fisica della Materia and of the Istituto Nazionale di Fisica Nucleare-Italy. The polish members of the working group acknowledge the contribution of the Polish State Committee for Scientific Research (Contract No. 5 P03B06220).

[1] F. Laviano, E. Mezzetti et al., Supercond. Sci. Technol., 16 (2003), 71
[2] F. Laviano, E. Mezzetti et al., Physical Review B 68 (2003), 014507
[3] F. Laviano, E. Mezzetti et al., Physica C 404 (2004), 220
[4] P. Przyslupski, M. Sawicki et al., J. Appl. Phys. 95 (2004), 2906
[5] P. Przyslupski, M. Sawickiet et al., Phys. Rev. B 69 (2004), in press