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Methoden und Instrumentierung Poster: Mi., 14:00–16:30 M-P37
Magneto-optics in the vicinity of the 2p and 3p edges of 3d transition metals
Armin Kleibert 1 , Volkmar Senz 1 , Karl-Heinz Meiwes-Broer 1 , Joachim
Bansmann 2 , Peter M. Oppeneer 3
1 Institut für Physik, Universität Rostock, D-18051 Rostock, Germany – 2 Abt.
Oberflächenchemie und Katalyse, Universität Ulm, D-89069 Ulm, Germany –
3 Department of Physics, Uppsala University, Box 530, S-751 21 Uppsala, Sweden
Soft x-ray based experimental techniques are powerful and very sensitive methods to
investigate the properties of systems with low dimensions such as ultrathin films or
clusters. During the last decade, resonantly enhanced magnetic dichroism occuring
after excitation of 2p core level electrons of the 3d transition metals has received much
attention. X-ray magnetic circular dichroism (XMCD) is one of the most prominent
phenomena within this filed of research, since it enables element-specific investigations
of the magnetic spin and orbital moments when measuring the respective x-ray absorption
spectra. However, all magneto-optical properties of a material are determined by
one and the same dielectric tensor and thus, it should be possible to obtain the same
information when from measuring the reflectivity. Experiments using the reflectivity
instead of photoabsorption especially profit from the much larger probing depth of
about 20-100 nm when compared to the commonly applied total electron yield detection
with a probing depth of 2-4 nm. Reflectivity measurements are hence attractive
investigation methods on buried layer in complex magnetic structures as, e. g., spin
valves.
In this contribution we will focus on the transverse magneto-optical Kerr-effect (T-
MOKE) and its different capabilities at the 2p and 3p edges of 3d transition metal
samples, respectively. On the one hand, we will present results that have been obtained
in in situ experiments at the 2p edges of ultrathin cobalt films using reflectivity
as well as conventional XMCD experiments [1]. On the other hand, we will present
measurements of the T-MOKE at the 3p edges of capped iron films and we will demonstrate
how to obtain the full set of optical constants in this energy regime where highly
circularly polarized radiation is usually not available. The elements of the dielectric
tensor taken from the T-MOKE experiments at the 3p edges will then be compared
to the corresponding data in the vicinity of the 2p core levels. The results will be
discussed with respect to future experiments on magnetic nanostructures.
[1] A. Kleibert, V. Senz, J. Bansmann, and P. M. Oppeneer, Phys. Rev. B 72, 144404
(2005)