Coexistence of half-metallicity and martensitic transition in Co2VGa1−xSbx (x = 0, 0.25 and 0.5) Heusler alloys: First-principles calculations combined with structural experiments

Abstract

Herein, we have investigated, theoretically and experimentally, the influence of Sb-doping, at Ga-site, on crystal structure, martensitic transition (MT) and half-metallicity of Co2VGa1−xSbx (x = 0, 0.25 and 0.5) Heusler alloys. The results reveal that the Co-V-Ga-Sb alloys with x = 0 and 0.25 exhibit typical half-metallicity, and at x = 0.25 the density of states (DOS) show a wider band gap near the Fermi level in minority states, which implies that Co2VGa0.75Sb0.25 is an efficient material with 100% spin polarization. Moreover, Co2VGa0.5Sb0.5 exhibits a martensitic transformation from parent phase with L21-type cubic structure to the D022-type tetragonal structure at ∼347 K. In addition, the DOS of Co2VGa0.5Sb0.5 also exhibit half-metallicity after expanding the lattice parameter by 2%. The unique features of Co2VGa1−xSbx Heusler alloys imply that these alloys are promising for high-efficiency spintronics and shape memory devices.