In situ magnetic force microscope studies of magnetization reversal of interaction domains in hot deformed Nd-Fe-B magnets

A hot-deformed Nd-Fe-B sample has been chosen for the investigation of interaction domains by means of magnetic force microscopy. During the imaging process, a magnetic field of up to 6 T was applied in situ along the easy axis of magnetization. The thermally demagnetized state presents a regular pattern of interaction domains with an average width of about 1 pm but with a much larger length scale. Starting from the thermally demagnetized state, magnetization along the initial magnetization curve occurs via sequential switching of neighboring grain columns at the peripheries of the interaction domains. Demagnetization of a saturated sample takes place through the nucleation and expansion of a patchy domain pattern with a much larger extension and a substructure in the lateral range of the underlying grain size. Reversal processes under an applied magnetic field also take place at the borders of the domains. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4712635]