Velocities, temperatures, and magnetic moments of cobalt and cobalt dominated alloy clusters in molecular beams

Atomic clusters, defined as aggregates of a few atoms, have strongly size dependent properties because of quantum confinement effects. The magnetic properties of small atomic clusters are dominated by quantum size effects and are different from bulk materials. Interesting magnetic phenomena such as the enhancement of spin and orbital moments, large magneticanisotropies, and size dependent magnetic screening have been predicted, but experimental confirmation is scarce and detailed understanding of the underlying mechanisms is missing. In this research project I will investigate isolated few-atom binary clusters with the objective to buildup fundamental knowledge about the magnetic interactions between the atoms and about the interplay of geometric structure and magnetism. The binary clusters will be produced in a laser vaporization source and will be studied in molecular beams, i.e., in absence of any support or medium. Temperature dependent magnetic deflection experiments will be used formagnetic characterization. Vibrational spectra of size selected clusters will be measured via infra-red multiple photon dissociation at an infra-red free electron laser. The geometries of the clusters will be identified by comparison of the experimental spectra with simulated spectra for different possible structural isomers using density functional theory calculations. Two types of magnetic interactions will be studied in different work packages via selected model clusters: the size- and composition-dependent magnetism of FeRh (3d-4d) and FePt (3d-5d) clusters containing less than 20 atoms, and the size- and temperature-dependent spin-flip screening in different 3d and 4f doped silver clusters: AgnCo, AgnMn,and AgnTb with n