Abstract: In this paper, we discuss the field-induced inhomogeneity in ferrofluids based on our theoretical analysis and experimental measurement. First, the dielectric tensor of the anisotropic media with particle chain is analyzed by using the electromagnetic theory. Second, based on a microscopic model, we discuss the behavior of the chain aggregation in the ferrofluids under external magnetic fields. Then, we relate the observable quantity-refraction index differences of the two propagating modes to the ratio between chains of different sizes and the strength of magnetic field. Finally, we experimentally measure the magneto-optical effect of ferrofluids by detecting polarization state change of the laser passing through the ferrofluids film, and the ratio between chains of different sizes is obtained by using computer simulation.

Key words: ferrofluids, magneto-optical effect, chain aggregation