Imaging domains of hard magnetic materials by SEM and MFM

The paper deals with observation of the magnetic domain structure of hard magnetic materials by the colloid-scanning electron microscopy (colloid-SEM) technique and the magnetic force microscopy (MFM) method. The specimens studied were anisotropic sintered Nd–Fe–B-based and SmCo5 magnets, produced by powder metallurgy route. Observations of the magnetic microstructure were carried out in the thermally demagnetized state of the magnets at the surface perpendicular to the alignment axis. The domain structure is of complicated character. The coarse domain pattern consists of the main domains (forming a maze pattern near the specimen surface) and surface reverse spikes. Besides the coarse domain structure, the presence of fine scale surface domains is revealed by MFM.