AC Magnetic Properties of Compacted FeCo Nanocomposites

Here we report the AC magnetic properties of soft magnetic nanocomposites made from compaction of Fe₁₀Co₉₀ nanoparticles. Following a discussion of previous work on soft magnetic nanocomposites, the sample preparation and experimental characterization by AC permeametry are described. The permeability is constant and equal to the DC value for low frequencies, but drops off sharply above a characteristic frequency f_c. A model is developed to explore the relation between f_c and material parameters including the effective anisotropy, exchange coupled volume, temperature, and saturation magnetization.