Combined Fokker-Planck-Brown and Yvon approach for describing the dynamic magnetic response of interacting ferroparticles in magnetic fluids

A. O. Ivanov - V. S. Zverev

Ural Federal University, 51 Lenin Av., 620000 Ekaterinburg, Russia

Abstract
We suggest a modified mean-field Fokker--Planck--Brown equation to describe the dynamic magnetic susceptibility of ferrofluids exposed to an AC magnetic field. The approach incorporates both the interparticle magnetic dipole-dipole interaction and the ferroparticle polydispersity. The model is investigated analytically and numerically for the case of weak, linear polarised, AC magnetic field. It is found that the dipolar interactions result in an observable growth of the imaginary part of the initial dynamic susceptibility in the low-frequency region, in a shift of the imaginary part maximum and in an increase of the real part low-frequency plateaux. Figs 2, Refs 31.