First-principles investigation of the martensitic transition and magnetic properties in Heusler alloys Mg2YZ (Y = Sc, Ti, V, Z = Al, Ga, In)

Abstract Crystal structure, magnetism, martensitic transition, electronic structure and mechanical properties of Heusler compounds Mg 2 YZ (Y = Sc, Ti, V, Z = Al, Ga, In) were studied by carrying out first-principles calculations based on density functional theory. All compounds in the cubic phase have an inverse Heusler structure with Hg 2 CuTi as the prototype. Mg 2 ScZ is paramagnetic and does not undergo a martensitic transition, while Mg 2 Ti(or V)Z undergoes a martensitic transition and shows ferromagnetism, which is basically unchanged (or smaller) with the phase transition. Y and Z atoms play major and minor roles, respectively, in the electronic structure, which directly affects the magnetism of the two phases. The calculated mechanical properties indicate that Mg 2 TiZ is ductile in the cubic phase and brittle in the tetragonal phase, while Mg 2 VZ has a similar brittleness in both the cubic and tetragonal phases. It is predicted that Mg 2 TiZ and Mg 2 VAl (or Ga) are prone to tetragonal distortion.