Electronic, magnetic and transport properties of Co2TiZ (Z=Si, Ge and Sn): A first-principle study

We have studied the electronic structure, magnetic and transport properties of some Co based full Heusler alloys, namely Co2TiZ (Z=Si, Ge and Sn), in the frame work of first-principle calculations. The calculations show that Co2TiZ (X=Si, Ge and Sn) are to be half-metallic compounds with a magnetic moment of 2 μB, well consistent with the Slater–Pauling rule. The electronic structure results reveal that Co2TiZ has the high density of states at the Fermi energy in the majority-spin state and show 100% spin polarization. Our results also suggest that both the electronic and magnetic properties in these compounds are intrinsically related to the appearance of the minority-spin gap. The origin of energy gap in the minority-spin states is discussed in terms of the electron splitting of Z (Z=Si, Ge and Sn) and 3d Co atoms and also the d–d hybridization between the Co and Ti atoms. The transport properties of these materials are discussed on the basis of Seebeck coefficients, electrical conductivity coefficients and thermal conductivity coefficients.