Berlin 2018 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 23: Graphene: Adsorption, Intercalation and Doping I (joint session O/TT)
TT 23.5: Talk
Monday, March 12, 2018, 16:00–16:15, MA 043
Decoupling of the graphene/ferromagnet interface by gold intercalation: Effect on optical constants — •Christine Jansing1, Hans-Christoph Mertins1, Markus Gilbert1, Maxim Krivenkov2, Andrei Varykhalov2, Oliver Rader2, Andreas Gaupp2, Andrey Sokolov2, Hud Wahab3, Heiko Timmers3, Dominik Legut4, and Peter M. Oppeneer5 — 1Münster University of Applied Sciences, Stegerwaldstr. 39, D-48565 Steinfurt — 2Helmholtz-Zentrum Berlin für Materialien und Energie, Albert Einstein Str. 15, D-12489 Berlin — 3University of New South Wales, Canberra, ACT 2600, Australia — 4IT4Innovations Center, VSB-Technical University of Ostrava, CZ-708 33 Ostrava, Czech Republic — 5Department of Physics and Astronomy, Uppsala University, S-75120 Uppsala, Sweden
X-ray absorption and reflectance spectroscopy of linearly polarized synchrotron radiation across the carbon 1s edge of graphene/Co/W and graphene/Ni/W is utilized to investigate the effect of gold intercalation on the complex optical constants of these systems. The pz-orbitals of graphene hybridize strongly with the 3d states of the ferromagnetic substrate. Hybridization effects can be reduced by intercalation of gold which also leads to a change in the optical constants. A complete set of optical constants was determined, describing the π*- and σ*- resonances of graphene. The absorption index k was directly deduced from the measured absorption spectra whereas the refractive index n has been extracted from k via a Kramers-Kronig transformation. Based on these optical constants reflection spectra have been simulated that are in good agreement with our experimental data.