Berlin 2012 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 8: Magnetic Particles / Clusters I
MA 8.2: Vortrag
Montag, 26. März 2012, 18:00–18:15, EB 202
XMCD studies of Ni nanoclusters on a graphene moiré template at the new WERA/MPI-IS 7T XMCD end station at ANKA — •Thomas Tietze1, Philipp Leicht2, Muriel Sicot2, Mikhail Fonin2, Peter Nagel3, Stefan Schuppler3, Michael Merz3, and Eberhard Goering1 — 1Max-Planck-Institut für Intelligente Systeme, 70569 Stuttgart — 2Fachbereich Physik, Universität Konstanz, 78464 Konstanz — 3Karlsruher Institut für Technologie, Institut für Festkörperphysik, 76021 Karlsruhe
Graphene grown on noble metal surfaces like Rhodium or Iridium can serve as a template for the growth of magnetic nanoparticles, e.g. Ni nano islands and ellipsoids. Here, we investigated the magnetic properties of in-situ grown Ni nanostructures on a graphene Moiré template on an Ir (111) single crystal by means of x-ray magnetic circular dichroism (XMCD). We investigated nanoclusters of different shapes, triangular (length 10 nm, height 2 nm) and spherical (diameter 4-5 nm), at different nominal coverage from only 0.2 to 1 monolayer, respectively. To reveal the magnetic behavior, we measured the Ni L2,3 edge XMCD signal at low temperatures (15 K) and at various applied magnetic fields up to 7 Tesla with the new fast switching MPI-IS XMCD end station at the WERA beamline at ANKA. We used sum rules to extract spin and orbital magnetic moments and found enhanced orbital moments for low nominal coverage. In order to study the magnetic anisotropy we performed XMCD measurements in different geometries to probe the in- and out-of-plane components of the Ni magnetic moments.