Study of Electronic Structure, Magnetism, and Half-Metallicity of New Heusler Compounds CsTmO₂ (Tm = Fe, Co, Ni, and Cu)

The density functional calculations were performed using the full-potential linearized augmented plane wave (FPLAPW) method for new Heusler alloys CsTmO₂ (Tm = Fe, Co, Ni, and Cu). All compounds were stable in FM AlCu₂Mn-type structure. Results revealed that these alloys can be experimentally synthesized according to the calculated cohesive and formation energies. CsTmO₂ (Tm = Fe, Co, Ni, and Cu) alloys in AlCu₂Mn-type and CuHg₂Ti-type structures were half-metallic ferromagnets. The origin of half-metallicity in CsNiO₂ alloy was also discussed. The total magnetic moment of CsTmO₂ (Tm = Fe, Co, Ni, and Cu) alloys in both structures were 3 μ_B per formula unit and obeyed the Slater-Pauling rule (M_tot = 22 − Z_tot). The relationship between the magnetism and half-metallicity of all compounds and the lattice constants was also studied. The half-metallic character in combined alloys CsTmO₂ (Tm = Fe, Co, Ni, and Cu) improved in comparison with Heusler alloys including transition metals which indicated that they may be good candidates for practical applications in spintronics.