Nonlinear susceptibilities and stochastic resonance in frozen dense ferrocolloids

Non-linear dynamical susceptibility and stochastic resonance in moderately concentrated solidified ferrocolloids have been studied theoretically. Magn etodipole interaction between ferromagnetic particles was taken into accoun t. The results suggest that due to this interaction the initial dynamical s usceptibility has no Debye form. Magnetodipole interaction decreases freque ncies corresponding to maxima of imaginary part of dynamical susceptibility . The signal-to-noise ratio increases with interparticle interaction. When the temperature is ion: enough, this parameter increases with amplitude of an external magnetic field. (C) 1999 Elsevier Science B.V. All rights reser ved.