Spin-polarized half-metallic state of a ferromagneticδlayer in a semiconductor host

Abstract

We discuss a model which is apt to describe the appearance of a spin-polarized half-metallic state around a single δ layer of a magnetic transition metal embedded into a nonmagnetic semiconductor host. We show that ferromagnetism in this system can be attributed to the intrinsic physical properties of the δ layer. The relevant physicaleffectsdescribedbyourmodelarethehybridizationoftheelectronstatesofthemetalandsemiconductor atoms, the charge redistribution around the δ layer, and the electron-electron correlation on a metal atom, which is the driving force of ferromagnetism. We obtain the mean-field phase diagram of the model at zero and finite temperature, both in the case when the chemical potential is fixed, and when the density of particles on the δ layer isfixed.Therelevanceofourresultsinconnectionwithnumericalandexperimentalresultsontheso-calleddigital magnetic heterostructures, in the absence and in the presence of a quantum-well carrier channel, is eventually discussed.