Dresden 2011 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 46: Surface magnetism I (jointly with MA)

O 46.7: Vortrag

Mittwoch, 16. März 2011, 12:45–13:00, CHE 184

Magnetic anisotropy of Co and Ni adlayers on diamond and GaAs surfaces: an ab-initio study — •Bernd Stärk, Peter Krüger, and Johannes Pollmann — Westfälische Wilhelms-Universität, Münster, Germany

We present ab-initio investigations of magnetic transition-metal multilayers on semiconductors. In our work, we focus on the description of noncollinear magnetic systems and their magnetic anisotropy. To this end, we employ density functional theory in the framework of both LDA and GGA using a basis set of Gaussian orbitals.

Adsorption of Co/Ni adlayers on C(111)/C(001)-(1x1) surfaces is distinguished by a very small lattice mismatch. For one adlayer we find the metal adatoms to be localized in positions saturating all surface dangling bonds. They form strong covalent bonds with the substrate atoms that markedly reduce the magnetic moment at the interface and can even change the direction of the easy axis of magnetization as compared to the free standing monolayer. Furthermore, we find a strong dependance of anisotropy energies on the number of adlayers.

Secondly, we also discuss Ni on GaAs surfaces. Recent experiments suggest [1] that Ni grows epitaxially in bcc structure on GaAs(001) and that its magnetic properties strongly deviate from the bulk fcc case. We present a thorough investigation of possible atomic structures for this system and their magnetic properties.

[1] C. S. Dian et al., PRL 94, 137210 (2005).