Magnetocaloric Effect in the Full‐Heusler Alloy Ga₂MnNi for Magnetic Refrigeration: A First‐Principles and Monte Carlo Study

In this manuscript, the magnetic and magnetocaloric properties of the MnNi compound are investigated using Monte Carlo simulations and first‐principles calculations. Initially, the electronic, structural, and magnetic characteristics of the alloy are explored. The findings indicate that the ferromagnetic state in the F m (No. 216) structure, with an optimal lattice parameter of 5.88 Å, was the most stable state compared to nonmagnetic (NM) and antiferromagnetic (AFM) states. Phonon dispersion studies confirm the alloy's dynamic stability, while the density of states reveal metallic behavior at the Fermi level. The total magnetic moment is calculated to be 3.48 . Additionally, exchange interactions are computed for Monte Carlo simulations, predicting a Curie temperature () of 331 K, consistent with experimental measurements ( = 330 K). Furthermore, the alloy exhibited a relative cooling power (RCP) of 1133.16 J kg −1 and a magnetocaloric effect of 19.65 J kg −1 K −1 at an applied magnetic field of 5 T. These results indicate that the MnNi full‐Heusler alloy is a potential option for use in magnetic refrigeration applications.