Tuning Magnetic Behavior of Lanthanum-Substituted Gd3Fe5O12: An Experimental Study

This letter covers the structural and magnetic properties of lanthanum-substituted gadolinium iron garnet (GIG) (Gd_3-xLa_xFe₅O₁₂), where the La ion was substituted at the Gd site. X-ray diffraction analysis suggested that the synthesized samples possess cubic crystal structure with an increase in lattice constant with La substitution. The crystallite size was estimated through the Williamson–Hall plot analysis and found to increase from 50.577 for ${x}$ = 0 to 67.343 nm for ${x}$ = 0.4. The room temperature magnetization value was increasing from 0.162 to 2.536 emu/g from pure to La-substituted GIG. These materials display a ferrimagnetic to paramagnetic phase transition as high temperature rose from 565 to 573 K, which is attributed to the high superexchange interaction between Fe³⁺ ions. In addition to transition, temperature magnetic compensation was also observed below room temperature. The coercivity of the samples was estimated from the room temperature hysteresis curve, which shows soft ferrimagnetic behavior. The stable crystal structure, low magnetic compensation, low coercive field, and high transition temperature make these materials suitable for communication devices.