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HL: Fachverband Halbleiterphysik

HL 9: Poster 1

HL 9.12: Poster

Montag, 23. März 2009, 14:30–17:00, P2

Magnetic properties of transition metal doped Si nanocrystals and their size dependence. — •Christian Panse¹, Frank Küwen², Roman Leitsmann¹, and Friedhelm Bechstedt¹ — ¹Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universtität Jena, Max-Wien-Platz 1, 07743 Jena, Germany — ²Energieforschungszentrum Niedersachsen, Technische Universität Clausthal, Am Stollen 19, 38640 Goslar, Germany

For investigation of the magnetic and spin-related properties of nanoparticles we examine transition metal doped semiconductors. In particular Si nanocrystals (NCs) doped with Mn and Fe atoms are under investigation. We consider two different impurity positions: substitutional and interstitial sites. The optimized geometries show bond-length deviations from the ideal geometry of less than 1.5% for nearest neighbor atoms. Interestingly in the Si-rich limit interstitial impurity sites lead to the most stable bonding configurations. In addition, the existence of a so-called self-purification effect is shown for very small Si NCs.

To verify Hund's rule for the NC systems we have analysed the spin and charge distribution in these systems in detail. A strong dependence of the total magnetic moment on the energetic position of the metal d-states with respect to the Fermi level could be observed.