Features of the Influence of Atomic Ordering on the Structural and Magnetic Properties of the Heusler Alloy Ni2Mn1.5Sn0.5

The effect of atomic ordering on the structural and magnetic properties of the crystal structures of the austenite and martensite phases of the Heusler alloy Ni2Mn1.5Sn0.5 has been studied within the density functional theory (DFT). The cubic L21, tetragonal L10, and orthorhombic 4O structures are considered. The L21 phase demonstrates a lower stability in view of its higher energy with respect to the L10 and 4O phases. The presence of the antiferromagnetic plane containing Mn atoms in the computational box of L10 makes it less favorable by 10 meV/atom in comparison with the 4O phase. However, dilution of the antiferromagnetic plane with Sn atoms leads to increasing stability of the L10 structure. An energetically favorable atomic configuration was predicted, at which the L10 structure becomes more favorable by 21 meV/atom than the 4O structure. The obtained results qualitatively describe the existing experimental data.