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Plenarvorträge - DPG-Tagungen

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Symposium X-RAY Magneto-Optics Dienstag<br />

Hauptvortrag SYXM 1.6 Di 17:00 H1<br />

Magnetic properties of mass selected transition metal clusters<br />

— •Wilfried Wurth 1 , Leif Glaser 1 , Tobias Lau 1,2 , Michael<br />

Martins 1 , Robert Nietuby`c 1 , and Matthias Reif 1 — 1 Institut<br />

für Experimentalphysik, Universität Hamburg, Hamburg, Germany —<br />

2 EPFL, Lausanne, Switzerland<br />

The magnetism of nanoparticles has attracted a lot of interest recently<br />

due to their promising properties for storage media. From a more fundamental<br />

point of view small clusters allow to study the transition from<br />

the magnetic properties of atoms to those of the respective solids.<br />

We have developed a cluster source which enables us to investigate size<br />

selected transition metal clusters deposited on solid surfaces using x-ray<br />

magnetic circular dichroism. In this talk recent results for iron clusters<br />

[1,2] and chromium clusters deposited on ferromagnetic substrates will<br />

be presented which demonstrate the strong size dependence of the<br />

magnetic properties of the clusters.<br />

[1] J.T. Lau, A. Föhlisch, R. Nietuby`c, M. Reif, and W. Wurth, Phys.<br />

Rev. Lett. 89, 57202 (2002)<br />

[2] J.T. Lau, A. Föhlisch, M. Martins, R. Nietuby`c, M. Reif, and W.<br />

Wurth, New J. of Phys. 4, 98.1 (2002)<br />

Hauptvortrag SYXM 1.7 Di 17:30 H1<br />

Coherent x-ray scattering and lensless imaging of magnetic<br />

materials — •Stefan Eisebitt 1 , Marcus Lörgen 1 , Wolfgang<br />

Eberhardt 1 , Jan Lüning 2 , and Joachim Stöhr 2 — 1 BESSY, Berlin,<br />

Germany — 2 SSRL, SLAC, Stanford, USA<br />

Coherent Scattering is sensitive to the individual sample geometry beyond<br />

statistical averages – this is the reason why the speckle fine structure<br />

in coherent scattering can be exploited for imaging and to track<br />

the dynamics of a sample. The basics of coherent x-ray scattering using<br />

synchrotron radiation sources will be reviewed, including advantages and<br />

limitations of ”lensless” imaging techniques. Magnetic scattering of soft<br />

x-rays and in particular polarization effects in the interference will be<br />

discussed in detail, as they have consequences for both static and dynamic<br />

studies of magnetic samples. Recent progress in magnetic domain<br />

imaging via coherent scattering will be presented. The future perspectives<br />

regarding the application of these techniques at free electron x-ray<br />

lasers, which will deliver a coherent photon flux many orders of magnitude<br />

higher than available today, will be discussed.

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