Regensburg 2010 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 33: Poster II
MA 33.29: Poster
Freitag, 26. März 2010, 11:00–14:00, Poster B1
Magnetic coupling in manganese doped silicon nanocrystals — •Christian Panse1, Roman Leitsmann2, and Friedhelm Bechstedt1 — 1Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany — 2GWT-TUD GmbH, Abteilung Material Calculations, Annabergstr. 240, 09125 Chemnitz, Germany
To understand the magnetic properties on a nanoscale we examine transition metal doped semiconductors. In particular silicon nanocrystals doped with manganese are under investigation. We consider two different doping positions: substitutional and interstitial sites. Single doped systems tend to create high spin phases (3 µB) while the magnetic density is strongly localized at the Mn doping site.
Our fully unconstrained density-functional studies on pairwise-doped NCs show a clear dependency of the strength and type of the magnetic coupling on the Mn-Mn distance d. Due to the localized magnetic moments of the Mn atoms the system favors strong antiferromagnetic ordering for d<2.9 Å. Larger distances yield weaker ferromagnetic coupling. Strong noncollinear spin effects could be found if the Mn atoms are separated by more than 5 Å. Unless the angle between both magnetic moments is less than 6∘ no significant energy gain due to noncollinearity occur.
A comparison of different doping sites show that the inclusion of at least one substitutional Mn atom will raise stability of the pairs significantly.