Nonlinear susceptibility and stochastic resonance in solid ferrocolloids

Theoretical analysis of the dynamic susceptibility and the signal-to-noise ratio for a moderately concentrated suspension of uniaxial monodomain spher ical ferroparticles in a solid matrix was performed. It was suggested that the axes of a weak particle magnetization are oriented in one direction and the alternating external magnetic field is parallel to these axes. Magneto dipole interaction of ferroparticles was accounted for by the successive pe rturbation theory. The effect of this interaction on dynamic response funct ions corresponding to the external field frequency and a multiple frequency was estimated. It was concluded that the Debye pattern of initial suscepti bility disappears as a result of interparticle interactions. Temperature de pendences of the components of the dynamic susceptibility and the signal-to -noise ratio pass through maxima; temperatures corresponding to these maxim a increase with the parameters of magnetodipole particle interactions.