Change in the magnetostructural properties of rare earth doped cobalt ferrites relative to the magnetic anisotropy

The superparamagnetic properties of the doped cobalt ferrite nanocrystals have been demonstrated. The significance of the sol–gel autocombustion method in yielding the as obtained doped cobalt ferrite oxide powder in the nano-range has been very well complemented with structural, dimensional and morphological analytical techniques such as X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), particle size analysis and Scanning Electron Microscopy (SEM). The lattice strain and lattice parameters have been calculated by making use of the Williamson–Hall extrapolation. The valence states of the metal ions and single phase formation of the polycrystalline oxides have been confirmed with the help of X-ray Photoelectron Spectroscopy (XPS) and Raman Spectroscopy. The magnetic measurements M–H and M–T have been carried out demonstrating a change in the magnetic moment and a superparamagnetic–ferrimagnetic transition in the ferrite system. The influence of the distribution of the metal ions in the crystal lattice and the dimensions of the ferrite oxides on the resultant magnetic properties has been demonstrated. The contribution of the spin–orbit coupling generating from the Co2+ ions in the octahedral lattice towards higher magnetic anisotropy and hence the magnetic properties is investigated. The results provide an insight into the inter-relationship of the particle dimension, the spin–orbit coupling and the resulting superparamagnetic property.