Magnetic properties of Ni-Co-based thick films investigated with magnetic force microscopy

Preliminary results are presented of a magnetic force microscopy (MFM) investigation to characterize Ni-Co-based screen-printed and fired films magnetically. These systems are of interest not only for contactless magnetoresistive sensors of mechanical quantities but also because they are made of micrometre sized grains sintered (and, in the case of Ni plus Co grains, alloyed) during the thermal process. Hence, a detailed study of their magnetic properties has been undertaken. Typical domain structures and zones have been observed by MFM at resolutions of about 0.2 mu m (static mode) and 50 nm (dynamic mode). Changes in the domain structure and deflection forces acting on the magnetic force microscope tips have been observed in samples prepared at various peak firing temperatures, and in samples of different compositions.