Magnetic force microscopy study of nanocrystalline Fe91Zr7B2 soft magnetic alloy

The domain structure of the nanocrystalline Fe91Zr7B2 alloy at the optimum soft magnetic state was studied by means of magnetic force microscopy (MFM), Curved domains separated by 180 ° walls were observed. The domain wall width (πLex, where Lex is the exchange correlation length) was estimated to be less than 2 ± 0,3 μm from the MFM image. This result is consistent with the Lex value ( ~ 0.5 μm) evaluated from the measured magnetic properties. These results reveal that the excellent soft magnetic properties are due to the averaging of the effects of the magnetocrystalline anisotropy (K1) over the order of 104 grains.