Vertical Bloch lines in garnet-type ferrite films for different dark-fieldmicroscopy geometries: Analysis of the visualization mechanism

Using the electrodynamic dyadic Green's function technique, the magnetoopti c diffraction of light and the formation of the magnetic structure's image in dark-field microscopy are considered. On the basis of the developed theo ry, the images of domain boundaries and vertical Bloch lines in garnet-type ferrite films are calculated for different observation geometries. Compari son of the numerical results with the experimental data indicate that, if t he light is incident in the plane of the domain boundaries, the Bloch lines are visualized due to the direct magnetooptic diffraction of light by the distribution of magnetization along the line.