Defects in half-metals and finite temperature

The influence of intrinsic defects in half-metals is calculated in the case of NiMnSb. Of the 14 cases of intrinsic defects, five affect the half-metallic properties. They are energetically very unlikely to occur. Circumstances are discussed under which defects may even have a beneficial effect on the spin polarization of the conduction electrons. Non-intrinsic defects, like deliberate doping by rare-earth atoms, as well as the effect of nano-structured contacts may influence the magnon spectrum, improving the behaviour at finite temperature.