Prediction of the structural and magnetic properties of the all-d-metal Heusler alloys Ni–Mn–Cr

In this work, all-d metal Heusler alloys Ni–Mn–Cr were predicted by first principles. Their structure, magnetism, tetragonal distortion and electronic properties were studied. The cubic groud state structures of Ni₂MnCr and NiMnCr₂ are XA type, and that of NiMn₂Cr is L2₁ type. All of them have magnetism. The change of their lattice constants is closely related to the covalent radius of atoms. Ni₂MnCr has a stable tetragonal phase and may undergo martensitic transition. NiMn₂Cr has a lower energy tetragonal phase, but is dynamically unstable. The equilibrium volumes of the two compounds expand through tetragonal distortion. NiMnCr₂ does not have a lower energy tetragonal phase. In the tetragonal distortion, the atomic magnetic moments are influnced by the interatomic distance and the magnetic moments of neighboring atoms. The origin of the tetragonal distortion and magnetic properties was discussed in terms of the electronic density of states.