Magnetic properties and origin of the half-metallicity of Ti2MnZ (Z=Al, Ga, In, Si, Ge, Sn) Heusler alloys with the Hg2CuTi-type structure

• Ti2MnZ (Z=Al, Ga, In, Si, Ge, Sn) are half-metallic ferrimagnets.
• Total magnetic moments of the Heusler alloys Ti2MnZ follow the µt=Zt−18 rule.
• Band gaps are determined by hybridization d states of the Ti1–Ti2 coupling and Mn atom.
• The s–p elements play an important role in the half-metallicity of these Heusler alloys.

Using the first-principles calculations within density functional theory, we investigate the magnetic properties and electronic structures of the Ti2MnZ (Z=Al, Ga, In, Si, Ge, Sn) alloys with the Hg2CuTi-type structure. The Ti2MnZ (Z=Al, Ga, In, Si, Ge, Sn) are found to be half-metallic ferrimagnets. The total magnetic moments (µt) of the Ti2MnZ alloys are calculated to be 0 for Z=Al, Ga, In and 1 for Z=Si, Ge, Sn, linearly scaled with the total number of valence electrons (Zt) by µt=Zt−18. The origin of the band gap for these half-metallic alloys is well understood. We expect our results to trigger further experimental interest in these alloys.