Study of faraday effect on Co$_{1-x}$Zn${_x}$Fe$_2$O$_4$ nanoferrofluids

Zinc doped cobalt ferrite Co$_{1-x}$Zn${_x}$Fe$_2$O$_4$ nanoparticles (x = 0.1, 0.5, 0.9) were synthesized by chemical coprecipitation method. The crystallite size, which was calculated from the full width half maximum (FWHM) value of the strongest peak (311) plane using Scherer approximation, was found to decrease with higher zinc content. The surface morphology of the powder samples was obtained using transmission electron microscopy (TEM). Magnetic properties, such as Saturation magnetization (M$_s$), Remanent Magnetization (M$_r$) and Coercivity of the powder samples, were measured using Vibrating Sample Magnetometer (VSM) at room temperature and were found to decrease with increased zinc content. Aqueous ferrofluids prepared from the powder samples were subjected to magnetic field to measure their Faraday rotation. Faraday rotation of the ferrofluids was found to increase with applied magnetic field and decrease with increasing zinc composition.