Systematic investigation of particle size dependence of magnetic properties in soft magnetic composites

The particle size dependence of selected magnetic properties of soft magnetic composites filled with iron particles at 60 vol.% was measured. For an ideal magnetization the maximum permeability mu(max) shows an increase with increased particle size d due to a decreased inner demagnetizing field, while the initial permeability mu(i) stays constant. The coercivity H-c shows a linear increase with increased inverse particle diameter 1/d. The effective number of active domain walls per particle is increased with an increased particle diameter due to the lower amount of defects and pinning places in composites containing large particles compared with smaller particles, and the anomaly factor eta is lowered following the relation eta = eta(f)(d/d(0)). (C) 2008 Elsevier B.V. All rights reserved.