Tuning Magnetocaloric Properties in Mn60Ga20-xInxC20 Antiperovskites via Isoelectronic Substitution of In

This work is a systematic investigation of the influence of the isoelectronic substitution of In for Ga on the crystal structures, magnetic behaviors, and magnetocaloric responses of Mn60Ga20-xInxC20 compounds (x = 1, 2, 3, 4, 5). The materials were synthesized using a ball milling technique. All compositions crystallized in a cubic anti-perovskite structure with space group Pm-3m. A low-temperature transition at Tt exhibits first-order characteristics and likely corresponds to a transition from a non-collinear antiferromagnetic-like (AFM) state to a ferromagnetic (FM) phase. At higher temperature, a second-order transition from the FM to the paramagnetic (PM) phase occurs at the Curie temperature (TC). As the In concentration increased, TC increased and Tt decreased, reaching 272 K and 149 K, respectively, for x = 5. These shifts are attributed to lattice expansion induced by In substitution. Among the compositions studied, the sample with x = 2 exhibited the highest magnetic entropy change (|∆SM| = 2.84 JKg-1K-1) near TC = 252 K for a magnetic field change of 5 T. These findings highlight the importance of structural tuning in optimizing magnetocaloric performance in Mn-based antiperovskite systems.