Abstract
We propose a model to describe the formation of a spin-polarized half-metallic state in the proximity of a ferromagnetic metal monolayer embedded into a semiconducting host. The main physical ingredients of our model are the Coulomb interaction between two electrons at the same metallic site, the charge redistribution around the monolayer and the hybridization between the electron states of the metal and of its host. We discuss the phase diagram of the model and the relevance of our results in connection with experimental and numerical results on digital magnetic heterostructures.