Dresden 2014 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 19: Poster I
MA 19.48: Poster
Dienstag, 1. April 2014, 13:00–15:30, P1
Comment on magnetic domain contrast in wide-field Kerr microscopy of bulk specimens — •Dominik Markó1,2, Rudolf Schäfer1,2, and Ludwig Schultz1,2 — 1IFW Dresden, Institute for Metallic Materials, Helmholtzstr. 20, D-01069 Dresden — 2TU Dresden, Institut für Werkstoffwissenschaft, D-01062 Dresden
Wide-field Kerr microscopy is based on an optical polarization microscope with Köhler illumination and provides immediate domain images of a certain sample area. MOKE loops are readily obtained by plotting the image intensity of selected sample areas as a function of the applied magnetic field and, by calibrating the domain contrast for applied saturation fields along different directions, it is possible to evaluate the domain contrast in a quantitative way.
In bulk specimens, however, the application of magnetic fields can lead to a significant phenomenon: due to the close distance of the objective lens to the sample, magnetic stray fields which emerge from the sample edges may cause a strong non-linear, position- and field-dependent Faraday effect in the objective. This leads to a field-dependent contribution to the domain contrast within the corresponding images and, therefore, to highly distorted hysteresis loops. In this presentation, this effect and its implications will be systematically analyzed on FeSi bulk samples.