Robust Half-Metallicity and Electronic Structure of the New Full-Heusler Compounds CsBaX2 (X = C, N, and O)

The electronic structure and magnetism of new Heusler alloys of CsBaX2 (X = C, N, and O) were investigated within density functional theory (DFT) using the self-consistent full-potential linearized augmented plane wave (FPLAPW) method. The CsBaC2 in the AlCu2Mn-type was a half-metallic ferromagnet while it was a nonmagnetic metal in CuHg2Ti-type structure. CsBaN2 and CsBaO2 compounds in both structures were half-metallic ferromagnets. The majority band gap for CsBaC2 in the AlCu2Mn-type was obtained equal to 1.67 eV and for CsBaN2 and CsBaO2 compounds in the AlCu2Mn-type (CuHg2Ti-type) structure were calculated equal to 2.34 (2.29) eV and 3.53 (2.76) eV, respectively. The origin of half-metallicity was also studied using the band structure calculations and density of states (DOSs). The total magnetic moments of CsBaC2, CsBaN2, and CsBaO2 compounds were, respectively, obtained as 5 mu (B) , 3 mu (B) , and 1 mu (B) per formula unit at the equilibrium lattice parameter, which were in agreement with Slater-Pauling rule (M (tot) =12-Z (tot)). The CsBaX2 (X = C, N, and O) compounds kept their half-metallic characteristic in a wide range of lattice constants in comparison with Heusler alloys including transition metals, which makes them promising and attractive materials in spintronic field.