Berlin 2005 – wissenschaftliches Programm

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MA: Magnetismus

MA 26: Hauptvortr
äge Fauth / Acet

MA 26.1: Hauptvortrag

Dienstag, 8. März 2005, 14:00–14:30, TU H1028

A spectroscopic look at small particle magnetism from the atom to nanoscale solids — •Kai Fauth — Physikalisches Institut der Univ. Würzburg, Am Hubland, 97074 Würzburg — Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, 70569 Stuttgart

The investigaton of (sub-) nanoscale objects must take the interaction with their environment into consideration, since they have a high proportion of surface atoms. In order to understand the role of these interactions, in particular with respect to magnetic properties, interaction - free particles should be compared with the same particles in the presence of interactions. X-ray magnetic circular dichroism (XMCD) proves to be a highly versatile tool to tackle this question, since it combines several advantages such as element specificity, high sensitivity and the possibility to disentangle spin and orbital contributions to the magnetization.

The presentation will discuss realizations of the above scenario for both, atoms and small Co and Ni clusters deposited from a molecular beam and magnetic nanoparticles (Co, FePt) prepared by chemical means. In the case of small clusters the magnetic properties of matrix-isolated clusters in Argon films are compared to those which are observed when they are exposed to a markedly interacting substrate. For the case of magnetic nanoparticles it will be shown that using mild reactive plasma treatments, full control over the chemical state of the particle surface can be obtained while preserving the integrity of the layer structure. In this way, the role of stabilizing ligands as well as of surface oxide formation can be investigated.