Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 2: Surface Magnetism and Spin Phenomena
O 2.7: Vortrag
Montag, 16. März 2015, 12:15–12:30, MA 004
Room-temperature magnetic ordering of an Eu monolayer under graphene on Ni and Co thin films — •Felix Huttmann1, David Klar2, Carolin Schmitz-Antoniak2, Antonio J. Martínez-Galera1, Alevtina Smekhova2, Nicolae Atodiresei3, Vasile Caciuc3, Stefan Blügel3, Heiko Wende2, and Thomas Michely1 — 1II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany — 2Fakultät für Physik and Center for Nanointegration (CENIDE), Universität Duisburg-Essen, Lotharstr. 1, 47048 Duisburg, Germany — 3Peter Grünberg Institut (PGI) and Institute for Advanced Simulation (IAS), Forschungszentrum Jülich, 52425 Jülich, Germany
We expose epitaxial graphene on ferromagnetic thin films of Co and Ni to vapor of the rare earth metal Eu at elevated temperatures, resulting in the intercalation of an Eu monolayer in between graphene and its substrate. The Eu monolayer forms a (√3 × √3)R30∘ superstructure with respect to the graphene lattice irrespective of any epitaxial rotation of graphene with respect to its Co or Ni substrate. We use X-ray magnetic circular dichroism at the Co and Ni L2,3, Eu M4,5, and C K edges as an element-specific technique to investigate magnetism in these systems. We find an antiferromagnetic alignment between Eu and Co/Ni moments, while for C, a dichroic signal is not unambiguously identified. Density functional theory calculations confirm the antiferromagnetic coupling and provide an insight into the coupling mechanism.