A first-principles study on the lower-valence coexisting Cr2TiX (X=Al, Ga, Si, Ge, Sn, Sb) Heusler alloys

The electronic, magnetic, and bonding properties of the Cr2TiX (X=Al, Ga, Si, Ge, Sn, Sb) Heusler alloys have been investigated using first-principles calculations. The results show that Cr2TiSb exhibits a half-metallic nature and Cr2TiGa and Cr2TiSn exhibit a nearly half-metallic nature. From analysis of the density of states and the electron density difference along the Ga→Sn→Sb series for sp atoms, we found that the Cr–Ti bond demonstrates covalent character with more or less the ionic and metallic nature. In addition, the Cr–Ti bonding strength increases along this series. All the compounds have a negative total magnetic moment, most of which are confined to the Cr atoms. There exists a 1.0μB increasing trend of the total moment along the III→IV→V main group for sp atoms, and only the total moment of Cr2TiSb coincides well with the Slater–Pauling behavior.