Spin canting phenomenon in cadmium doped cobalt ferrites, CoCd xFe2-xO4 (x = 0•0, 0•2, 0•4, 0•6, 0•8 and 1•0), synthesized using sol-gel auto combustion method

Abstract

Synthesis of non-collinear (spin canted) ferrites having the formula, CoCdxFe2-xO4 (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0), has been carried out using the sol-gel auto combustion method. The ferrite samples show an interesting magnetic transition from Neel to Yafet-Kittel configuration, as the Cd2+ concentration is increased beyond x = 0.4. The FT-IR spectra confirm the formation of the metal oxide bond as they exhibit two frequency bands in the range of ∼595 cm-1 and ∼450 cm-1, corresponding to the tetrahedral and the octahedral stretching vibrations of the metal oxide, respectively. The structural evolutions of the nanophase investigated using powder X-ray diffraction (XRD) technique show that the average crystallite size is ∼35 nm. The magnetic studies reveal that the saturation magnetization, Ms, increases up to x = 0.4 and decreases when the value of x is >0.4. It is proposed that the incorporation of Cd2+ ion takes place into the tetrahedral sites and up to x = 0.4, Neel's model is followed. But for x > 0.4, canting of spins occurs, as explained by Yafet-Kittel (Y-K) model. The d.c. resistivity decreases as a function of temperature, indicating semiconducting nature of the ferrites and the positive value of Seebeck coefficient establishes p-type conduction behaviour for all the ferrite samples. © Indian Academy of Sciences.