Electronic and structural properties of ferromagnetic shape memory alloys studied by density functional theory

Abstract

The electronic and structural properties of different members of the Ni-Mn-Ga family calculated by ab initio density functional theory are discussed. From total energy calculations, we show that the martensitic phase is the stable low temperature phase. Moreover, occurrence of ferromagnetic and paramagnetic martensitic phases for Ni₂MnGa and Ni_2.25Mn_0.75Ga, respectively, are explained. Modifications in the density of states near the Fermi level EF are observed across the martensitic transition for Ni₂MnGa, as well as in Mn₂NiGa. While Ni₂MnGa is ferromagnetic, we find Mn₂NiGa to be ferrimagnetic. The calculated lattice constants and the magnetic moments are in good agreement with experiment.