Frequency-dependent permeability tensor for unsaturated polycrystalline
ferrites is derived through an effective medium approximation that combines
both domain-wall motion and rotation of domains in a single consistent
scattering framework. Thus derived permeability tensor is averaged on a
distribution function of the free energy that encodes paramagnetic states for
anhysteretic loops. The initial permeability is computed and frequency spectra
are given by varying macroscopic remanent field.Comment: 24 pages, 3 figure