Intensity-based Wide-field Magneto-optical Microscopy

In conventional Kerr- and Faraday microscopy the sample is illuminated with plane-polarized light and a magnetic domain contrast is generated by an analyzer making use of the Kerr- or Faraday rotation. In this presentation we review possibilities of analyzer-free magneto-optical microscopy based on magnetization-dependent intensity modulations of the light: (i) The transverse Kerr effect can be applied for in-plane magnetized material, demonstrated for an FeSi sheet. (ii) Illuminating the same sample with circularly polarized light leads to a domain contrast with a different symmetry as the conventional Kerr contrast. (iii) Circular polarization can also be used for perpendicularly magnetized material, demonstrated for a garnet film and an ultrathin CoFeB film. (iv) Plane-polarized light at a specific angle can be employed for both, in-plane and perpendicular media. (v) Perpendicular light incidence leads to a domain contrast on in-plane materials that is quadratic in the magnetization and to a domain boundary contrast. (vi) Domain contrast can even be obtained without polarizer.