Magneto-electronic and thermoelectric properties of some Fe-based Heusler alloys

We present electronic, magnetic and transport properties of some 24-valence-electron semiconducting Heusler alloys obtained by first principles and use of Boltzmann theory. The spin-resolved electronic structures show that the materials are semiconductors in both spin channels and that they follow the ZT − 24 Slater-Pauling rule in the Fm3¯m phase. In Fe2TiSi, Fe2TiGe and Fe2ZrSi, the shape and size of the band gap is mainly determined by d-d hybridization between the d-states of transition metal atoms Ti (Zr) and Fe. Decreasing covalent character in bonding is observed when Y and Z atoms are replaced by the corresponding atoms lower in the group. The transport properties predict the materials to have p-type character, with electrical conductivity and the Seebeck coefficient having a semiconductor-like nature in all three compounds studied. The large Seebeck coefficients at room temperature strongly support the possible application of these materials as thermoelectric materials.