Absorption of AC field energy in a suspension of magnetic dipoles

Energy absorption produced by non-interacting single-domain ferromagnetic particles suspended in a liquid matrix is studied. The particles are assumed to be rigid dipoles so that all the dissipation in the system is due to the viscous flow induced in the matrix by orientational motion of the particles in response to a linearly polarized uniform AC field. The kinetic approach employed is valid for arbitrary values of the field frequency and amplitude. Comparison of the results obtained against those of the conventional phenomenological description reveals that the amplitude–frequency dependencies delivered by the latter are limited to weak field regimes.