A local magnetization study of epitaxial Nd-Fe-B films by magnetic force microscopy

The magnetization process of epitaxial, granular Nd-Fe-B films is studied by magnetic force microscopy by imaging the magnetic domain structure in small magnetic fields and different subsequent remanent states. As expected for nucleation type magnets, low magnetic fields are sufficient to move domain walls. However, in order to create a high remanent single domain state, domain walls have to be expelled completely from the individual grains. Therefore, the required magnetic fields are found to be grain size dependent and are on average about half the coercive field