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.

We investigated the structural, magnetic, magnetocaloric, and magnetotransport properties of Ni₅₀Mn₃₅In₁₅ Heusler alloys via partial substitution of Ni with 3 at.% Bi (Ni₄₇Bi₃Mn₃₅In₁₅) and 3 at.% Si (Ni₄₇Si₃Mn₃₅In₁₅) synthesized by arc melting. X-ray diffraction confirms a predominantly L2₁ cubic structure (space group Fm-3m), while SEM/EDX analysis verifies compositional homogeneity. Temperature-dependent magnetization measurements reveal that the Bi-substituted alloy exhibits a first-order magnetostructural transition associated with the martensitic transformation, followed by a second-order magnetic phase transition from ferromagnetic to paramagnetic behavior near the Curie temperature. In contrast, the Si-substituted alloy shows a single second-order transition with negligible thermal hysteresis, indicating suppression of the martensitic phase. The Curie temperature decreases from 324 K for the parent alloy to 313 K and 286 K for the Bi- and Si-substituted alloys, respectively. A maximum magnetic entropy change of 6.0 Jkg⁻¹K⁻¹ and 4.5 Jkg⁻¹K⁻¹ is observed for the Bi- and Si-substituted alloys, respectively, under an applied magnetic field change of 50 kOe, with corresponding relative cooling power values of 303 Jkg⁻¹ and 345 Jkg⁻¹. These results demonstrate that lattice expansion (Bi) and contraction (Si) distinctly modify Mn–Mn exchange interactions, enabling tunable magnetocaloric performance in Ni–Mn–In Heusler alloys.

We investigated the structural, magnetic, magnetocaloric, and magnetotransport properties of Ni₅₀Mn₃₅In₁₅ Heusler alloys by partial substitution of Ni with 3 at.% Bi (Ni₄₇Bi₃Mn₃₅In₁₅) and Si (Ni₄₇Si₃Mn₃₅In₁₅) synthesized by arc-melting. X-ray diffraction confirms a predominant L₂₁ cubic structure (space group Fm-3m), while SEM/EDX verifies compositional homogeneity. Temperature-dependent magnetization measurements reveal that the Bi-substituted alloy exhibits a first-order magnetostructural transition associated with the martensitic transformation, followed by a second-order ferromagnetic–paramagnetic transition near the Curie temperature. In contrast, the Si-substituted alloy shows a single second-order transition with negligible thermal hysteresis, indicating suppression of the martensitic phase. The Curie temperature decreases from 324 K for the parent alloy to 313 K and 286 K for the Bi- and Si-substituted alloys, respectively. A maximum magnetic entropy change of 6.0 Jkg^-1K^-1 and 4.5 Jkg^-1K^-1 is obtained under an applied magnetic field change of 50 kOe for the Bi- and Si-substituted alloys, respectively, with corresponding relative cooling power values of 303 Jkg^-1 and 345 Jkg^-1. These results demonstrate that lattice expansion (Bi) and contraction (Si) distinctly modify Mn–Mn exchange interactions, enabling tunable magnetocaloric performance in Ni–Mn–In Heusler alloys.