Effect of Magnetic Contact on Macroscopic Permeability of Soft Magnetic Composite

It is revealed that the contact of magnetic particles in soft magnetic composite (SMC) significantly increases the macroscopic permeability. It is shown that Ollendorff's formula, which assumes homogenous magnetic particles and insulation layers, underestimates the macroscopic permeability of SMC. It is suggested that the excess in the permeability is due to the local contacts among the magnetic particles. The effect of the magnetic contact is evaluated using a magnetic circuit model.