Prediction of a new class of half-metallic antiferromagnets

We report on vacancy induced half-metallicity in the prototype Mott-insulating substances MnO and NiO. By embedding a cation-vacancy into a magnetic system a new road opens up to the construction of half-metallic antiferromagnets. For Ni$_{0.97}$O we find a half-metallic antiferromagnet a system hitherto only proposed for complicated crystal structures.