The Magneto-Dielectric Anisotropy Effect in the Oil-Based Ferrofluid

Abstract

The dielectric parameters of an oil-based ferrofluid with magnetic nanoparticles were measured in combination with a magnetic and electric field. Three types of measurements were carried out over wide frequency ranges from 10 mHz to 2 MHz, at various temperatures, using a capacitance method. The magneto-dielectric effect of the dissipation factor (tan $$\delta $$ ) was observed for constant magnetic flux density of value 200 mT. In a magnetic field, the interaction between the magnetic field and the magnetic moments of nanoparticles leads to the aggregation of magnetic nanoparticles into various structures. In these structures were rearranged charges around nanoparticles which had an influence on their dielectric parameters. These parameters were also measured over a linear increase and decrease of the magnetic flux density to 200 mT. The dependence of the real part of a complex dielectric constant and tan $$\delta $$ at constant magnetic flux density in dependence on the angle with the electric field (anisotropy) were also measured. These parameters were changed linearly with increasing angle and dependent on the temperature. From the monotonic change of studied parameters with angle resulted that thin chains of nanoparticles were created in the ferrofluid.