Demagnetizing field effect on the complex permeability spectra of ferromagnetic metal flake composite materials in the microwave frequency range

Complex permeability spectra of Permendur and Cobalt flake composite materials in the microwave frequency range has been studied to reveal the demagnetizing field effect. The permeability spectrum of ferromagnetic metal composites depends on the shape and the alignment direction of embedded particles; demagnetizing field induced in the particles affects the magnetic permeability and the magnetic resonance frequency of the composite material. In the Permendur composites, a negative permeability caused by the magnetic resonance is obtained and its frequency dispersion can be controlled by the demagnetizing field in the embedded particles as well as the particle content in composite structure.