Abstract
Magnetic force microscopy (MFM) has been used to image the magnetic stray field from a (Pr/Nd)FeB hard magnetic alloy containing α-Fe regions. Images were acquired with three different sensing tips (CoCr, NiFe and Fe/SiO2 coated Si). The MFM images were compared to optical Kerr effect images from the same area. Kerr images of the (Pr,Nd)2Fe14B grains were similar to MFM images obtained using the CoCr tip, revealing a regular open-flux magnetic structure for those grains imaged on a plane perpendicular to the easy direction and stripe domains on those grains imaged on a plane containing the easy direction. MFM images indicated that the α-Fe particles were single domain, while Kerr images suggested a substructure within α-Fe. The low coercivity NiFe and Fe/SiO2 sensing tips provided images only of the magnetic domain boundaries. The difference in image characteristics between the CoCr and NiFe and Fe/SiO2 tips is believed to be associated with the extent to which the initial tip magnetisation is changed by the stray field from the sample.
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