Magneto-Optic Faraday Effect of Magnetic Fluids Based on MFe₂O₄ (M = Fe, Ni, Co) Particles

A study is performed of the magneto-optical Faraday effect of magnetic fluids based on MFe₂O₄ particles (M = Fe, Ni, Co) in which sodium oleate is used as dense surfactant. This allows Faraday rotation to be obtained at a low volume concentrations of these particles (0.25–0.5%). Rotation depends linearly on the strength of the magnetic field (500–1000 G), which is unsaturated up to 4000 G. The maximum effect is achieved for magnetic fluids based on CoFe₂O₄.