Possible Martensitic Transformation in Heusler Alloy Pt_2MnSn from First Principles

Using density functional theory calculations, we investigate the tetragonal distortion, electronic structure and magnetic property of Pt_2MnSn. The results indicate that, when the volume-conserving tetragonal distortion occurs, the energy minimum appears at c/a=0.84, and the energy difference between the minimum and cubic phase is as high as 107 meV/f.u. Thus from the point of view of thermodynamics, martensitic transformation may occur in Pt_2MnSn with decreasing the temperature. The electronic structure of its cubic and martensitic phases also approves this. Moreover, both the cubic and tetragonal phases of Pt_2MnSn are ferromagnetic structures and their total magnetic moments are 4.26 \mu__\rm B and 4.12 \mu__\rm B, respectively.