Half-metallic properties in Co2XSn (X = Ti, V and Cr) full-Heusler compound

First-principles calculations based on density functional theory (DFT) confirm the half-metallic ferromagnetism in both Co2TiSn and Co2VSn, and the nearly half-metallic ferromagnetism in Co2CrSn Heusler alloys with the AlCu2Mn-type structure (L2(1)). The electronic band structures and density of states (DOS) calculations of the Co2TiSn and Co2VSn compounds show that the spin-up electrons are metallic, whereas the spin-down bands are semiconducting with a gap of 0.47 eV and 0.53 eV, respectively, with 0.21 eV and 0.36 eV as a spin-flip gap, respectively. The Co2TiSn and Co2VSn Heusler were half-metal compounds with magnetic moment of 2 mu B and 3 mu B at the equilibrium lattice constants a = 6.097 angstrom and a = 6.026 angstrom, respectively, which agrees with the Slater-Pauling rule, and have 100% polarization for a wide range of lattice parameters. The Co2CrSn is a nearly half-metal (NHF) compound with magnetic moment of 4.01 mu B and 92.9% polarization at the equilibrium lattice constants a = 5.995 angstrom and acquire half-metal behavior under the pressure 16.70 GPa.