Crystallographic and magnetic characteristics of thin-film Ni_0.5Co_0.5Fe₂O₄ ferrimagnet prepared by a sol-gel
deposition method were investigated by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy
(XPS), and vibrating sample magnetometry (VSM). The mixed ferrite Ni_0.5Co_0.5Fe₂O₄ specimen was found
to be polycrystalline having cubic spinel structure with slightly reduced lattice constant compared to CoFe₂O₄.
The XPS data indicate that Co and Ni ions in Ni_0.5Co_0.5Fe₂O₄ have charge valence of +2. The VSM measurements
indicate that the Ni_0.5Co_0.5Fe₂O₄ film have saturation magnetization, remanent magnetization, and coercivity
of 257 emu/cm3, 115 emu/cm3, and 0.5 kOe, respectively, which are 62 %, 68 %, and 29 % of those of
CoFe₂O₄. The reduction of the magnetic parameters of Ni_0.5Co_0.5Fe₂O₄ compared to CoFe₂O₄ is primarily
attributable to the smaller magnetic moment of high-spin Ni²⁺ ion (2 μB) than that of Co²⁺ ion (3 μB).