Competing magnetic states in novel full Heusler alloys: A DFT investigation of spin dynamics in diverse crystal structures of Mn2PtZn

Abstract

This study employs first-principles calculations to explore the structural stability of the cubic (Cu₂MnAl, Hg₂CuTi) and tetragonal phases of the Mn₂PtZn full-Heusler alloy in both ferromagnetic (FM) and antiferromagnetic (AFM) spin configurations. We used the Perdew-Burke-Ernzerhof generalized gradient approximation GGA and GGA + U to calculate the exchange–correlation energy.Key properties analyzed include cohesive and formation energies, structural, elastic, mechanical, and magnetic properties, phonon dispersion, thermodynamic stability, electronic band structure, and density of states. Our results indicate that the FM phases possess total magnetic moments of 7.89μ_B and 7.86μ_B for the cubic Cu₂MnAl and Hg₂CuTi structures, respectively, while the tetragonal structures exhibit moments of 7.50μ_B and 7.69μ_B. In contrast, the AFM phases show a total magnetic moment of 0 μ_B, with the tetragonal AFM phase being the most energetically favorable among those studied. We also assessed the elastic and mechanical properties, confirming that the alloy meets the Born criteria for mechanical stability, suggesting ductility and anisotropic behavior. Additionally, we investigated the dynamic properties and the projected partial density of states for the Mn₂PtZn alloy in both cubic and tetragonal phases. Dynamic stability was observed in all FM and AFM phases, except for the FM and AFM Hg₂CuTi phases. The spin-polarized electronic band structures and density of states for the AFM tetragonal phase, calculated using GGA and GGA + U, reveal metallic behavior for both majority and minority spin channels, with magnetization primarily arising from the 3d states of manganese atoms. These findings suggest that the Mn₂PtZn alloy is a promising candidate for spintronics and data storage applications.