An experimental analysis of the correlation between electronic structure and room temperature magnetism in Cu-doped CoFe2O4 spinel ferrite

Cu-doped CoFe2O4 spinel ferrites with composition CuxCo1-xFe2O4: x = 0.05, 0.1, 0.15, 0.2 have been synthesized by sol–gel self-combustion method. Cation distribution using XRD data by intensity ratio and Rietveld method revealed perfect inverse spinel structure, further confirmed with Vibration Sample Magnetometer (VSM) results explaining two sub-lattice collinear models. The room temperature VSM analysis reveals ferromagnetism in all compositions of the samples with a maximum saturation value of 73.587 emu/g at 1.5 T for the composition x = 0.15 and maximum coercivity 1754.67 G and squareness ratio 51% for the composition x = 0.2. The above result may be the highest value of coercivity and squareness ratio reported at room temperature for Cu- doped CoFe2O4 spinel ferrites. The electron density distribution using XRD data utilizing Maximum Entropy Method (MEM) visualizes the electronic structure. All compositions show strong tetrahedral A–O covalent bonding with Oxygen ions. Moderate covalent octahedral B–O ionic bonding for the compositions x = 0.05, 0.1 and 0.15 and ionic bonding for the composition x = 0.2 are observed. The composition Cu0.2Co0.8Fe2O4 with the maximum tetrahedral covalent and octahedral ionic bonding has the highest observed magnetic parameters. Graphical abstract