The study of structural, electronic, magnetic and magnetocaloric properties of antiperovskite carbides M3AlC (M=Mn and Fe): DFT combined with Monte Carlo simulation

Abstract

This work aims to investigate the structural stability, magnetic and electronic properties of M₃AlC antiperovskites using density functional theory (DFT) and Monte Carlo simulation. The obtained ground state results reveal that the antiperovskites M₃AlC are stable in the ferromagnetic (FM) state with a metallic character. The calculated total magnetic moments are 5.21${\mu }_B$ and 3.34${\mu }_B$ for Mn₃AlC and Fe₃AlC, respectively, with the total moments mainly from the M atom. The ferromagnetic behavior is confirmed by computing the density of state at Fermi level and verified the Stoner criterion. The magnetic and magnetocaloric behavior of M₃AlC is investigated using Monte Carlo simulation and the obtained results demonstrate that the transition from ferromagnetic to paramagnetic state occurs at $T_C=300$$$K and $T_C=230$$$K for Mn₃AlC and Fe₃AlC, respectively. These values of $T_C$ are in good agreement with the experimental results. The magnetocaloric effect and critical behavior are studied and the obtained values of magnetic entropy change $|\mathrm{\Delta }{S}_{\mathrm{\text{mag}}}|$ at 4.5$$T is about 4.242$$J/kg.K and 3.666$$J/kg.K and the relative cooling power (RCP) are 342.434$$J/kg.K and 325.26$$J/kg.K for Mn₃AlC and Fe₃AlC at 4.5T, indicating that these compounds are more appropriate for magnetic refrigeration. Finally, the critical exponents ($\beta$,$\gamma$,$\delta$) are calculated and the obtained values are close to the values of mean-field model.