Using density-functional theory within the generalized gradient approximation, it was shown that Si-based heterostructures with 1/4 layer δ-doping of interstitial Mn (Mnint) were half-metallic. For Mnint concentrations of 1/2 or 1 layer, the states induced in the band gap of δ-doped heterostructures still displayed high spin polarization, about 85% and 60%, respectively. The proposed heterostructures were more stable than previously assumed δ layers of substitutional Mn. Contrary to widespread belief, the present study demonstrated that interstitial Mn could be utilized to tune the magnetic properties of Si, and thus provides a new clue for Si-based spintronics materials.

Density-Functional Theory Study of Half-Metallic Heterostructures - Interstitial Mn in Si. H.Wu, P.Kratzer, M.Scheffler: Physical Review Letters, 2007, 98[11], 117202