Half-metallicity and magnetism of quaternary Heusler compounds CoRuTiZ (Z=Si, Ge, and Sn)

First-principle calculations based on the density functional theory for new quaternary Heusler compounds CoRuTiZ (Z=Si, Ge, and Sn) were performed. It was found that all three compounds were stable at Y-I structure in ferromagnetic state. The CoRuTiSi, CoRuTiGe, and CoRuTiSn were half-metal with integer magnetic moments of 1.00 mu(B) per formula unit and half-metallic gaps of 0.13, 0.10, and 0.01 eV at their equilibrium volume, respectively. The density of states (DOSs) and band structures of these compounds were studied and the origin of half-metallicity was discussed. The CoRuTiSi, CoRuTiGe, and CoRuTiSn compounds showed halfmetallic characteristics at lattice constants ranges of 5.77-6.36 angstrom, 5.66-6.16 angstrom, and 5.83-6.23 angstrom, indicating the lattice distortion did not affect the half-metallic properties of these compounds which makes them interesting materials in the spintronic field.