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O: Oberflächenphysik
O 28: Postersitzung (Elektronische Struktur, Grenzfläche fest-flüssig, Halbleiteroberflächen und -grenzflächen, Magnetismus und Symposium SYXM, Methodisches, Nanostrukturen, Oberflächenreaktionen, Teilchen und Cluster, Zeitaufgelöste Spektroskopie)
O 28.84: Poster
Mittwoch, 10. März 2004, 16:00–19:00, Bereich C
X-ray magneto-optical sum rules in small Co clusters — •Kai Fauth1,2, Markus Heßler1,2 und Gisela Schütz2 — 1Physikalisches Institut der Universität Würzburg, Am Hubland, 97074 Würzburg — 2MPI für Metallforschung, Heisenbergstraße 3, 70569 Stuttgart
The so-called spin and orbital sum rules [1,2] in x-ray
magnetic circular dichroism (XMCD) spectroscopy are often
believed to apply with reasonable accuracy in the case of the
late 3d transition metals and their compounds, if the magnetic
dipole term Tz can be neglected. Strong deviations can occur
due to symmetry breaking such as given at surfaces, causing the
magnetic dipole term to contribute significantly to the spin sum
rule, while not contributing to the magnetization. Much less is
known in the case of small clusters. We have derived magnetic
moments of superparamagnetic Co55 clusters from XMCD at various
applied magnetic fields. We find that the moments thus obtained
from the magnetization curve and those determined separately from the sum
rules agree to within 10%. This result sets an
upper limit for the importance of Tz in these clusters.
B. T. Thole et al. , Phys. Rev. Lett. 68, 1943 (1992)
P. Carra et al. , Phys. Rev. Lett. 70, 694 (1993)