, Volume 65, Issue 1, pp 65-77

Dynamic Birefringence in Ferrocolloids in Crossed Fields: Interaction of Magnetic and Mechanical Orientational Degrees of Freedom

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Abstract

A dynamic birefringence in a ferrocolloid placed in constant and variable crossed magnetic fields is considered. It is assumed that the energy of magnetic anisotropy of colloid nanoparticles is finite so that a magnetic moment can rotate both inside the particle and together with the particle. This “two-channel” pattern of a process significantly affects the kinetics of colloid macroscopic birefringence, that is the character of low-frequency dispersion of this value. Theoretical model is based on the generalized Fokker–Planck equation describing the interaction of internal and external orientational diffusion in a magnetic particle. Calculation results are presented in the form of so-called integral relaxation time; the convenience of this value for the characterization of multimode transient processes is shown.