Spin-polarized half-metallic state of a ferromagnetic delta layer embedded in a semiconducting matrix

I discuss a model to describe the occurrence of a spin-polarized half-metallic state around a delta layer of magnetic transition metal atoms embedded into a non-magnetic semiconducting matrix. The intrinsic physical properties of a single delta 
layer are responsible for ferromagnetic order in this system. The relevant physical ingredients of the model are the hybridization of the d electron states of the transition metal with the (s,p) electron states of the semiconductor, the charge redistribution  around the delta layer, and the electron-electron correlation on the d orbitals of the transition metal atoms, which is the driving 
force of ferromagnetism. The seminar is preceded by a tutorial introduction to the formalism of second quantization for Fermi systems.