The magnetic properties of Mn-doped cobalt ferrite films prepared by the spin-coating method

The films of Co1−xMnxFe2O4 (x = 0 − 0.4) were prepared on the substrates of Pt (111)/Ti/SiO2/Si by the sol-gel method. The effect of mole fraction of doping Mn ions on the microstructure, ferromagnetism and optic properties was investigated. The results show that, when x is less than 0.4, Mn ions have dissolved into the crystal lattices of CoFe2O4 without forming secondary phases. The surfaces of the films of Co1−xMnxFe2O4 possess polygonal and dense structures. The results of Raman show that Co2+ migrates from octahedral interstice to tetrahedral interstice when x is greater than 0.2. The results of XPS indicate that, in the Co0.8Mn0.2Fe2O4 film, Fe ions exist in the form of Fe2+ and Fe3+ and Mn ions exist in the form of Mn2+ and Mn3+. The results also show that, with increasing mole fraction of Mn ions, the values of saturation magnetization increase firstly, then decrease. When x is equal to 0.2, there is the maximum value of saturation magnetization (443.12 emu·cm−3).