Gradient diffusion in concentrated ferrocolloids under the influence of a magnetic field

The effect of interparticle interactions on the gradient diffusion of magnetic grains in a concentrated ferrocolloid under the influence of an external magnetic field is considered. The interparticle interactions are described using the formalism of the direct correlation function, which is related to the value of the thermodynamic force acting on a ferroparticle. The application of a simple representation of the direct correlation function allows one to evaluate the contributions of short- and long-range correlations of the particles to the ferrocolloid gradient diffusion anisotropy. The short-range correlations are negligible in the case of low-concentration fluids. In concentrated ferrocolloids the contributions of short- and long-range correlations to the coefficient of diffusion are of the same order. The theoretical results are compared with the data of a recent experimental study of gradient diffusion in concentrated ferrocolloids.