Ferromagnetism of magnetic semiconductors: Zhang-Rice limit

It is suggested that $p-d$ hybridization contributes significantly to the hole binding energy $E_b$ of Mn acceptors in III-V compounds, leading in an extreme case to the formation of Zhang-Rice-like small magnetic polarons. The model explains both the strong increase of $E_b$ and the evolution of a Mn spin-resonance spectrum with the magnitude of valence-band offsets. The high Curie temperature above room temperature is shown to be in accordance with the mean-field Zener model.