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HL: Fachverband Halbleiterphysik

HL 33: New materials

HL 33.2: Vortrag

Mittwoch, 28. März 2007, 17:00–17:15, H15

Interstitial Mn in Si: half-metallic heterostructures studied by density-functional theory — Hua Wu^1,2, •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 (Mn_sub) as done for Mn-doped GaAs and Ge, although Mn_sub impurities in Si are energetically less stable than interstitial Mn (Mn_int). In this work, we investigate the role of Mn_int impurities for ferromagnetism in Si, and propose a novel type of heterostructures with Mn_int    δ -doping. Using density-functional theory within the generalized gradient approximation, we show that Si-based heterostructures with 1/4 layer δ -doping of Mn_int are half-metallic. For Mn_int 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 Mn_sub. 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.