First-Principles and Experimental Studies of Structural, Electronic, and Magnetic Properties of Nickel Substituted Magnesium Ferrite Spinel

Using first-principles density functional theory calculations we investigate the effect of a nickel substitution on the structural, electronic, and magnetic properties of magnesium ferrite Mg_1 1pt - 1pt xNi_xFe_2O_4 ( x = 0, 0.4, and 1). The calculated lattice constant (8.38 Å) and magnetic moment (3.57 μ B ) of Fe atom are in reasonable agreement with the present experimental values from the present neutron scattering measurements. The presence of Ni is found to decrease the electronic band gap and eventually leads to a metallic character at x = 1. Moreover, based on the Maxwell–Boltzmann statistical analyses, we have predicted that Mg_1 1pt - 1pt xNi_xFe_2O_4 phases can have mixed spin configurations in a real sample, which in turn determines the measured magnetic properties.