Optimizing performance of half-metals at finite temperature.

Several aspects of half-metallic magnetism at finite temperature are discussed. Since NiMnSb is the simplest half-metal and the longest known it will be used as an example. Also it is a half-metal with remarkable little on-site Coulomb repulsion. Consequently it is a half-metal that is not notably corrupted by non-quasiparticle states. There exists an anomaly at 90 K, described before, that will be shown to be unrelated to the position of the Fermi level in the bandgap. Several substitutions are investigated that could shed some light on the origin of the transition. The calculated phonon spectrum is compared with experimental neutron scattering data. Finally, the spin-polarization of interfaces of NiMnSb with the transition metal based non-magnetic semiconductors NiTiSn and CoTiSb is investigated and the electronic structure of an infinite two-dimensional array of NiMnSb quantum dots embedded in NiScSb is reported.