d super(0) ferromagnetic surface in HfO sub(2)

Using first-principles simulations based on density functional theory, we demonstrate that surfaces of simple oxides can be ferromagnetic without involving magnetic transition metal ions, thus called d super(0) ferromagnetic surface. We take cubic HfO sub(2) as an example to show that the surface electronic states depend critically on the surface termination and only O rich non-stoichiometric surfaces are ferromagnetic. Systematic studies of various surfaces with different surface indexes and terminations indicate that the O surface electronic states are spin polarized due to the large O 2p spin exchange energy. We argue that the mechanism proposed here is rather general and can be applied to other simple oxides such as SrO.