Weak field magnetic susceptibility of ferrofluid emultions: the influence of droplet polydispersity

I. M. Subbotin - A. O. Ivanov

Institute of Mathematics and Computer Sciences, Ural Federal University, 51 Lenin Ave., 620000 Ekaterinburg, Russia

Abstract
A theoretical model has been developed to describe the weak field growth of magnetic susceptibility of ferrofluid emulsion considering droplet polydispersity. The initial static susceptibility of the polydisperse ferrofluid emulsion is proved to be independent on ferrofluid droplet polydispersity. In a weak external magnetic field, the emulsion susceptibility increases parabolically with the external field strength. Ferrofluid droplet polydispersity affects this growth within the ratio of mean values of the forth power of the droplet radius and the third power, that is 〈R⁴ 〉/ 〈R³ 〉. Figs 3, Refs 18.