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 10 mu(B) 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. (C) 2009 Elsevier B.V. All rights reserved.