Over 100 MHz cut-off frequency mechanism of Fe-Si soft magnetic composites

Soft magnetic composites of spherical Fe-5wt%Si particles insulated by epoxy resin are studied. The cut-off frequency increases from 7 MHz to 110 MHz by changing particle size from 116 mu m to 24 mu m. By applying a DC field to remove the displacement of domain wall and reversal magnetization of domain, the mechanism of cut-off frequency and permeability is discussed. Combining with the extended effective medium theory, the cutoff frequency and permeability in the range of MHz comes from the nature resonance modulated by eddy current. Weaking the effect of eddy current in magnetic particle is an effective way to increase the cut-off frequency of soft magnetic composites.

Automated summary

This study investigates soft magnetic composites made of spherical Fe-5wt%Si particles insulated by epoxy resin. By changing the particle size, the cutoff frequency can be increased. The mechanism of cutoff frequency and permeability is discussed by applying a DC field to remove the displacement of domain wall and reversal magnetization of the domain. The cutoff frequency and permeability in the MHz range are found to be influenced by the natural resonance modulated by eddy current. Weakening the effect of eddy current in the magnetic particle is an effective way to increase the cutoff frequency of soft magnetic composites.