Regensburg 2007 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 33: New materials
HL 33.2: Talk
Wednesday, March 28, 2007, 17:00–17:15, H15
Interstitial Mn in Si: half-metallic heterostructures studied by density-functional theory — Hua Wu1,2, •Peter Kratzer3, and Matthias Scheffler2 — 1II. Physikalisches Institut, Universität zu Köln, D-50973 Köln, Germany — 2Fritz-Haber-Institut der MPG, D-14195 Berlin, Germany — 3Fachbereich Physik, Universität Duisburg-Essen, D- 47048 Duisburg, Germany
Adding magnetic functionality to the most common semiconductor, Si, is in its infancy. So far, research on Mn-doped Si has concentrated on substitutional Mn (Mnsub) as done for Mn-doped GaAs and Ge, although Mnsub impurities in Si are energetically less stable than interstitial Mn (Mnint). In this work, we investigate the role of Mnint impurities for ferromagnetism in Si, and propose a novel type of heterostructures with Mnint δ -doping. Using density-functional theory within the generalized gradient approximation, we show that Si-based heterostructures with 1/4 layer δ -doping of Mnint are half-metallic. For Mnint concentrations of 1/2 or 1 layer, the δ -doped heterostructures still display a high spin-polarization of conduction electrons, about 85% and 60%, respectively. The proposed heterostructures are more stable than previously assumed δ -layers of Mnsub. Contrary to wide-spread belief, the present study demonstrates that interstitial Mn can be utilized to tune the magnetic properties of Si, and thus provides a new clue for Si-based spintronics materials.