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Magnetismus Vortrag: Mi., 17:40–18:00 M-V13
Time, layer, and spatially resolved magnetic domain imaging of layered
magnetic structures by x-ray magnetic circular dichroism photoelectron
emission microscopy
Wolfgang Kuch 1 , Keiki Fukumoto 1 , Jan Vogel 2 , Julio Camarero 3 , Fabien
Romanens 2 , Stefania Pizzini 2 , Marlio Bonfim 2 , Jürgen Kirschner 4
1 Freie Universität Berlin, Institut für Experimentalphysik, Arnimallee 14, D-14195
Berlin – 2 Laboratoire Louis Neel, CNRS, 25 avenue des Martyrs, F-38042 Grenoble,
France – 3 Universidad Autónoma de Madrid, E-28049 Madrid, Spain – 4 Max-Planck-
Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle
Magnetic structures consisting of ferromagnetic layers separated by ultra-thin nonmagnetic
spacer layers exhibit many new and interesting effects. The fundamental
investigation of the magnetization dynamics of such layered magnetic structures calls
for a method capable of delivering microscopic magnetic information about each of
the magnetic layers separately. X-ray magnetic circular dichroism photoelectron emission
microscopy (XMCD-PEEM) is such a technique. It combines the layer-resolved
visualization of magnetic domain patterns at surfaces and in buried layers with a timeresolved
stroboscopic measurement of the magnetization reversal dynamics, taking advantage
of the time structure of the synchrotron radiation. Using this time-resolved,
layer-selective microscopic technique we observed evidence for the importance of a local
magnetic interlayer coupling mediated by magnetostatic stray fields emanating from
domain walls. During the fast magnetization reversal, stray fields from domain walls
in the hard magnetic layer can lead to a locally enhanced domain nucleation and thus
to a faster switching of the soft magnetic layer. The images show furthermore that
the speed of domain wall motion is influenced by the domain wall energy, leading to
a lower velocity when domains are small. This becomes apparent as a delay in the
nucleation of reversed domains.