Field dependence of magnetooptic effect in magnetic colloid with superparamagnetic particles

Abstract

The field dependences of magnetic birefringence in two samples of magnetic fluid with different average particle size are investigated. It is established that the dependences of magnetic birefringence are parabolic. Significant difference in experimental data and calculations using the single-particle birefringence model was found. The experimental results are interpreted by the polydispersity of the particles in the samples, as well as by the presence of small aggregates with a partially compensated magnetic moment.

Spectral Dependencies of Magnetooptical Effects in Magnetic Fluids

“…More complex mechanisms of optical anisotropy in a magnetic colloid are associated with the formation of ordered structures under the action of a field: chains, labyrinths, or quasicrystalline formations of nanoparticles similar to a photonic crystal [15]. Following [10,20], birefringence and dichroism in a colloid of single-domain magnetic particles under the action of an external magnetic field can be described by the expressions:…”

“…When studying the spectral dependences of optical effects in magnetic fluids, transmission spectra are mainly studied [19]. The spectra of the effects of magnetic birefringence and dichroism were studied in [13,20]. For the theoretical interpretation of optical effects in magnetic colloids and predicting the properties of magneto-optical devices, accurate data on the optical properties of colloidal particles and a dispersion medium are required.…”