The dynamical properties of the magnetohyphen;optical effects of magnetic fluids thin films were investigated. The thin films, 12 mgr;m thick, of magnetite colloidal particles in water solvents and alkylnaphthalene one were prepared. A pulsed magnetic fieldH(t) was generated in a single turn coil by discharging a 40hyphen;kV capacitor bank. The intensityI(t) of the transmitted light through the two crossed polarizers and the films located in the coil was measured. The relaxation process of the magnetohyphen;optical effect can be described in terms of a single relaxation time, tgr;=3 mgr;s, for a waterhyphen;based magnetic fluid, while the relaxation time constant for alkylnaphthalene one depends on the field strength. These dynamical properties can be interpreted by the timehyphen;dependent Ginzburgndash;Landau theory by introducing the order parameter of the colloidal particles.
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