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.

• The magnetic moment of Co-V-Ga alloy can be enhanced by Sb substitute for Ga. • Both Co 2 VGa and Co 2 VGa 0.75 Sb 0.25 alloys exhibit a half-metallic band structure. • Excess substitution of Sb for Ga in Co 2 VGa 1− x Sb x compounds can induce martensitic transformation. • Coexistence of both half-metallic and martensitic transition was obtained in Co 2 VGa 1− x Sb x system alloys. 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 Co 2 VGa 1− x Sb x (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 Co 2 VGa 0.75 Sb 0.25 is an efficient material with 100% spin polarization. Moreover, Co 2 VGa 0.5 Sb 0.5 exhibits a martensitic transformation from parent phase with L2 1 -type cubic structure to the D0 22 -type tetragonal structure at ∼347 K. In addition, the DOS of Co 2 VGa 0.5 Sb 0.5 also exhibit half-metallicity after expanding the lattice parameter by 2%. The unique features of Co 2 VGa 1− x Sb x Heusler alloys imply that these alloys are promising for high-efficiency spintronics and shape memory devices. [ABSTRACT FROM AUTHOR]