THE PERMEABILITY TENSOR OF COMPOSITE CONSISTING OF MAGNETIC PARTICLES

The demagnetizing energy of spheroidal magnetic particles dispersed in cubic lattices has been calculated. The demagnetizing energy contains contributions from the demagnetizing self-energy and magnetostatic coupling energy between particles. The total demagnetizing energy can be conveniently expressed in terms of three demagnetizing factors whose sum equals unity. For low volume loading of particles the self-energy contribution is the dominant one, which is insensitive to particle coordinations and can be approximated by that of an isolated particle. However, when particle loading increases appreciably, significant differences arise for different particle lattices (sc, bcc, and fcc). One advantage of our formulation is that the permeability tensor of the composite can then be calculated for either a magnetic nonsaturated or saturated state of the particle. In contrast to conductivity calculations at the percolation limit there is no divergence of the permeability.