Prediction of the structure, magnetic properties, and martensitic transition of Mg-V-Ga Heusler alloys using first-principles calculations

Abstract

The structures, martensitic transition, and magnetic and electronic properties of Mg8VxGa8−x (x = 2, 3, 4, 5, 6) Heusler alloys were investigated using first-principles calculations. The structures for the substitution of extra atoms for deficient atoms are not energetically favorable. The strength and quantity of the interatomic bonds determine the lowest energy structures of compounds. With the increase in x, the lattice constants do not change monotonously, which is related to the shifting of the accumulated electrons in the covalent bonds. The magnetic moments of extra V are antiparallel to that of V at the normal sites. In the process of tetragonal deformation, the magnetic moment of V is closely related to the distance from the other V atoms. The martensitic transition may occur in all of the compounds studied herein. The splitting of the V d orbital indicates that the transition is due to the structural Jahn-Teller effect.