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MA: Fachverband Magnetismus

MA 38: Magnetic Nanoparticles

MA 38.12: Talk

Thursday, March 19, 2015, 12:30–12:45, H 0110

Magnetism of free Rh clusters via ab-initio calculations: which intuitive concepts can or cannot be used — •Ondřej Šipr¹, Hubert Ebert², Sergey Mankovsky², and Ján Minár^{2, 3} — ¹Institute of Physics ASCR, Praha, Czech Republic — ²Universität München, München, Germany — ³University of West Bohemia, Plzeň, Czech Republic

A fully relativistic ab-initio study on free Rh clusters of 13-135 atoms is performed to identify general trends concerning their magnetism and to check whether concepts which proved to be useful in interpreting magnetism of 3d metals are applicable to magnetism of 4d systems. Some important intuitive concepts which proved to be useful in interpreting magnetism of 3d metals are not applicable to magnetism of 4d systems (such as Rh clusters). In particular, there is no systematic relation between local magnetic moments and coordination numbers. On the other hand, the Stoner model appears to be well-suited as a criterion for the onset of magnetism of Rh clusters and, on the top of that, it can serve as a guide for the dependence of local magnetic moments on the local density of states at the Fermi level.

Fully-relativistic calculations indicate that in some cases there can be large orbital magnetic moments antiparallel to the spin magnetic moments. The intra-atomic magnetic dipole T_z term can be quite large at certain sites, however, as a whole it is unlikely to affect the interpretation of x-ray magnetic circular dichroism (XMCD) experiments based on the sum rules.