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MA: Magnetismus

MA 32: Magnetic Particles / Clusters

MA 32.2: Vortrag

Donnerstag, 30. März 2006, 15:30–15:45, HSZ 401

Influence of temperature on the magnetic properties of clusters — •Svetlana Polesya¹, Sven Bornemann¹, Jan Minár¹, Voicu Popescu¹, Ondrej Šipr², and Hubert Ebert¹ — ¹LMU München, Dept. Physikalische Chemie, München, Germany — ²Institute of Physics Acad. of Science, Prague, Czech Republic

We investigate the temperature-dependence of the magnetisation of free Fe clusters and of supported Co clusters on Pt(111) and on Au(111). Electronic and magnetic properties of these systems at T=0 K are calculated ab-initio via a scalar-relativistic multiple-scattering formalism. Exchange coupling parameters are then obtained from zero-temperature results and employed for describing magnetic excitations at finite temperatures within a classical Heisenberg Hamiltonian. In that way, one can interconnect ground-state and finite-temperature properties. The mean magnetisation and magnetic profiles of clusters was evaluated by the Monte Carlo method. We show how the magnetic profiles of clusters change if the temperature is varied and how the dependence of mean cluster magnetisation on the cluster size is influenced by the temperature. In particular it turns out that for small clusters the critical temperature in general does not increase monotonously with the cluster size.