Preparation and magnetic properties of the CoFe2O4 thin films on Si substrate by sol-gel technique

A stable precursor for CoFe2O4 thin film was prepared by sol-gel technique from the aqueous solution of FeCl3·6H2O and CoCl2·6H2O. Sol was deposited on a naturally oxidized silicon-substrate by spinning technique (2000 rpm) and heat treated at different temperatures ranging from 700 to 1100 °C. Thickness of the films was controlled in the range of 400–500 nm and all the films were characterized by using XRD and SEM. The effects of temperature and the composition on the formation of CoFe2O4 thin film were also studied. Films obtained at relatively lower temperature showed multi-phases of α-Fe2O3, CoFe2O4 and CoO while the formation of CoFe2O4 phase increases with increasing temperature. Furthermore, the composition of the solution in mol% has great role on the formation of CoFe2O4 films and the film containing 50 mol% of Co2+ exhibited CoFe2O4 mono-phase. Surface morphology of the films was studied by scanning electron microscope (SEM). Magnetic properties of the films, studied by using vibrating sample magnetometer (VSM), showed relatively high saturation magnetization (8.04–22.21 kWb/m2) as well as high coercivity (44.59–63.30 kA/m). Saturation magnetization also increases with increasing heat treatment temperature.