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MA: Fachverband Magnetismus
MA 51: Electron Theory of Magnetism
MA 51.5: Talk
Friday, April 4, 2014, 10:30–10:45, HSZ 401
Ab initio calculation of crystal field parameters for single Holmium atoms at a surface — •Martin Hoffmann1,2, Matthias Geilhufe2, Sergey Ostanin2, Wolfram Hergert1, Ingrid Mertig1,2, and Arthur Ernst2,3 — 1Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, Germany — 2Max-Planck-Institut für Mikrostrukturphysik, Halle, Germany — 3Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Germany
The direction of the magnetic moments of atoms at a surface depends strongly on the anisotropy of the underlying material. In most cases, the determination of the simple uniaxial anisotropy is sufficient to describe the orientation of the moments. However, this is only the first term in the more general crystal field Hamiltonian H. Higher terms couple e.g. different sublevels of the energy spectrum of an adsorbed atom.
Based on the electronic density of the substrate and the ad-atom, the parameters for this H can be calculated by ab-initio methods. We will present the implementation of this scheme for the Korringa-Kohn-Rostoker Green’s function method.
As application example, we calculated for a single Holmium (Ho) atom at a Pt(111) surface at first the position and the electronic and magnetic properties. With theses quantities we obtained the crystal field parameters for H, which can be further solved by exact diagonalization for the magnetic states of Ho. The resulting energy splitting is in very good agreement with experimental results.