Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 41: Poster Session I (Semiconductor Substrates: Epitaxy and growth; Semiconductor Substrates: Adsorbtion; Semiconductor Substrates: Solid-liquid interfaces; Semiconductor Substrates: Clean surfaces; Oxides and insulators: Epitaxy and growth; Oxides and insulators: Adsorption; Oxides and insulators: Clean surfaces; Organic, polymeric and biomolecular films - also with adsorbates; Organic electronics and photovoltaics, Surface chemical reactions; Heterogeneous catalysis; Phase transitions; Particles and clusters; Surface dynamics; Surface or interface magnetism; Electron and spin dynamics; Spin-Orbit Interaction at Surfaces; Electronic structure; Nanotribology; Solid/liquid interfaces; Graphene; Others)

O 41.72: Poster

Dienstag, 23. März 2010, 18:30–21:00, Poster B1

Ab initio investigations of Co and Ni adlayers on wide-band-gap semiconductors — •Bernd Stärk, Peter Krüger, and Johannes Pollmann — Westfälische Wilhelms-Universität, Münster

Metal-semiconductor hybrid systems feature novel functionalities which are not feasible with metals or semiconductors alone, combining, e.g., the high conductivity and spin-polarization of ferromagnets with the controllability of semiconductors. In this contribution, we present the results of a comparative study of Co and Ni multilayers on diamond as well as SiC surfaces employing the generalized-gradient approximation of density-functional theory.

Adsorption of Co/Ni adlayers on the C(001)/C(111)-(1x1) surface is distinguished by a very small lattice mismatch. For one adlayer the metal adatoms are found to be located in a position where all surface dangling bonds are saturated. They form covalent pd bonds giving rise to characteristic bonding and antibonding bands which exhibit no significant spin splitting. These bonds markedly reduce the magnetic moment at the interface. Adding further adlayers reveals that this effect is very localized and does hardly affect neighboring metal layers. Spin polarization at the Fermi level is quite large amounting to about 50% which is a prerequisite to spintronic applications.

Furthermore, we compare this behaviour to Co/Ni-deposited 6H-SiC(0001) surfaces. They show complex 2√3× 2√3 reconstructions due to a large lattice mismatch between the substrate and the adlayers. We discuss implications on the structural and electronic properties and compare our results to experimental findings.