Thin film deposition of undoped and Ni-doped cobalt ferrite on MgO (110) substrates using pulsed laser deposition technique

Abstract

The thin film samples of pristine and Ni-doped Cobalt ferrite(CFO) are deposited on MgO(110) substrates through pulsed laser deposition technique. The recorded X-ray diffraction scans of the samples confirms the thin film deposition of the said material on the given substrate. From the Atomic Force Microscopy studies, the surface roughness of CoFe1.7Ni0.3O4 thin film is found to be 0.62 nm, which is more than CoFe2O4 and CoFe1.5Ni0.5O4 (0.34 nm and 0.45 nm), attributed to the surface defects and recrystallization process. The x-ray photoelectron emission spectroscopy (XPS) survey spectra of the thin film samples confirm the presence of Co, Ni, Fe, O and C. In our case, the XPS-wide scans revealed the +2-oxidation state for Co and +2 as well as +3 oxidation states for Fe. The respective binding energy positions and the ratio of relative contribution to the overall intensity of Co and Fe ions at the octahedral and tetrahedral sites are also discussed in this paper. It has been shown that the Field Cooled-Zero Field Cooled magnetization curves do not merge until 400 K, which confirms that the Curie temperature Tc is higher than 400 K.