First-principles study of half-metallic properties of the Heusler alloy Ti2CoGe

First-principles calculations have been performed on the electronic structures and magnetic properties of a new Ti2Co-based full-Heusler alloy Ti2CoGe. The calculations predict the Ti2CoGe is a half-metallic ferromagnet at the equilibrium lattice constant with the minority-spin energy gap of 0.60 eV. It is found that the total magnetic moment (Mt) and the number of valence electrons (Zt) in Ti2CoGe obey a new Slater–Pauling (SP) rule of Mt=Zt−18 and the rule also can be applied to other Ti2Co-based half-metallic full-Heusler alloys. The Ti2CoGe alloy keeps a 100% polarization at Fermi level and maintains the half-metallic character for lattice constants ranging between 6.05 and 6.67 Å.

► The Ti2CoGe alloy in CuHg2Ti-type structure is predicted to being half-metallic ferromagnetic nature.
► A new Slater–Pauling rule of Mt=Zt−18 in normal Ti2Co-based half-metallic full-Heusler alloys has been proposed.
► The half-metallic character of Ti2CoGe can be maintained for the range between 6.05 and 6.67 Å.