Spin canting phenomenon in cadmium doped cobalt ferrites, CoCd _x Fe_2−x O ₄ ( _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, CoCd _x Fe_2 − x O ₄ (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 Cd^2 + 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, M _s , increases up to x = 0·4 and decreases when the value of x is >0·4. It is proposed that the incorporation of Cd^2 + 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.