First-Principles Calculations of the Effect of Substitutional Defects in Mn2CoV1-xScx (x = 0, 0.25, 0.50, 0.75, 1) Full Heusler Alloys Using Density Functional Theory and Monte Carlo Simulations

Density functional theory (DFT) and Monte Carlo simulations were employed to investigate the structural, mechanical, magnetic, thermomagnetic, and electronic properties of Mn ₂ CoV _1 − x Scₓ full Heusler alloys (x = 0, 0.25, 0.50, 0.75, 1). The results reveal minor variations in elastic modulus and lattice parameters across compositions. Band gap calculations using the Perdew-Burke-Ernzerhof (PBE) method show near-zero values for Mn ₂ CoV and Mn ₂ CoSc, with intermediate band gaps for mixed compositions. Total magnetic moments range between 2 and 4 µB, with Mn-Co exchange interactions dominating the magnetic coupling. A second-order phase transition from ferromagnetic to paramagnetic behavior occurs at Curie temperatures (Tc) between 450K and 1000K, decreasing with higher Sc concentrations. These findings demonstrate that Sc substitution systematically modifies the properties of Mn ₂ CoV _1 − x Scₓ alloys, making them potential candidates for spintronic and thermomagnetic applications.