Electronic structure and magnetism of binary Fe-based half-Heusler alloys Fe2Z (Z=In, Sn, Sb and As)
The electronic structure and magnetic properties of Fe-based binary half-Heusler alloys Fe2Z (Z=In, Sn, Sb and As) have been studied. It is found that binary Fe2Z has a site preference similar to normal ternary ones. Hybridization between the d states of Fe (A) and Fe (B) leads to the formation of a d-d band gap near EF. This gap is broadened and shifted to low energy as Z varies from In to Sb, which makes Fe2Sb a half-metal. The half-metallicity of Fe2Sb is insensitive to the lattice distortion. The spin polarization ratio is always 100% from 5.6 Å to 6.2 Å. The spin polarization of Fe2As is also high at equilibrium lattice constant. With a small expansion of the lattice, it becomes an ideal half-metal. Fe2Z alloys are all ferromagnets with parallel aligned Fe spin moments.