Visualizing the propagation of volume magnetization in bulk ferromagnetic materials by neutron grating interferometry (invited)

In this article we report on a neutron interferometry technique based on diffraction gratings which was used to visualize the geometry-dependent magnetization processes in bulk ferromagnetic materials. The contrast origin is based on the refraction of unpolarized neutrons at magnetic domain walls and the obtained image is termed neutron dark-field image (DFI). The magnetization process is imaged by measuring the spatially resolved domain wall density distribution of the sample. The sample under investigation was a polycrystalline steel plate where the magnetization process was imaged for different sample orientations. The DFI results of the magnetization processes were verified on the one hand by complementary neutron small angle scattering (SANS) experiments and on the other hand by finite element method (FEM) simulations. The obtained SANS and FEM results verify the same magnetization process behavior as observed in the DFI results.