Magnetic domain structures of Co22Ag78 granular films observed by magnetic force microscopy

A magnetic force microscope (MFM) was used to image the topography and magnetic microstructures of Co22Ag78 granular films. The observed morphology shows isolated nanometer-scale cobalt particles (granules) embedded in the silver matrix. Stripe magnetic domains with much larger size (typically of similar to 100 nm wide) than that of cobalt particles are resolved clearly on MFM micrographs for the annealed samples. It is demonstrated that the domain width and the relative magnetic force strength first increases and then decreases with annealing temperature with a maximum at about 600 K. We suggest that the appearance of the stripe domains is attributed to magnetic correlation among many of the isolated single-domain cobalt particles and is dependent on the microstructure of the samples. (C) 1998 American Institute of Physics. [S0003-6951(98)01119-X].