[Zurück]

A. Buchsbaum:
"Structural and magnetic properties of Fe and Co clusters on Alumina on Ni3Al(111)";
Vortrag: Seminar Institut für Allgemeine Physik (IAP), TU Wien; 27.04.2010.

Growing nanoparticles with well-defined size, shape and structure is an essential prerequisite to understand their magnetic properties. Templates are not only a means to grow regularly arranged clusters but also provide the opportunity to grow well-defined clusters with a narrow size distribution by simple evaporation, taking advantage of the fact that the capture zones of equidistant clusters have equal area.
In particular, I will demonstrate the applicability of an ultrathin alumina film on Ni3Al(111) as a template for growing Pd, Fe and Co clusters with a 4.1-nm lattice and a tuneable size between 1 and ≈1000 atoms. The structure of the ≈5 Å thick oxide film exhibits holes at the corner of the ( )R12.2° unit cell reaching down to the metal substrate. Pd atoms trapped in these corner holes create metallic nucleation sites where the clusters can nucleate and form a well-ordered hexagonal arrangement on the oxide nanomesh. We have applied different methods like scanning tunneling microscopy (STM), surface x-ray diffraction (SXRD), grazing-incidence small-angle x-ray scattering (GISAXS) and x-ray magnetic circular dichroism (XMCD) to determine the morphology, crystallographic and magnetic properties of the clusters.