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MM: Fachverband Metall- und Materialphysik
MM 42: Electron Microscopy II - Advances in characterisation
MM 42.1: Talk
Wednesday, April 2, 2014, 12:00–12:15, IFW B
High-Energy Plasmons in MoS2 and graphene heterostructures — •Michael Mohn1, Ralf Hambach1, Philipp Wachsmuth1, Gerd Benner2, and Ute Kaiser1 — 1Electron Microscopy Group of Materials Science, Ulm University, 89081 Ulm, Germany — 2Carl Zeiss Microscopy GmbH, 74447 Oberkochen, Germany
We investigate high-energy plasmons using momentum-resolved electron energy-loss spectroscopy and ab-initio calculations for molybdenum disulfide (MoS2) mono- and multilayers and MoS2-graphene heterostructures.
Energy-loss spectra up to 50 eV have been obtained using a Zeiss Libra 200 based low-voltage transmission electron microscope (SALVE I [1]) with an in-column energy filter. The plasmon dispersion has been studied for momentum transfers along different crystallographic axes within the Brillouin zone. Ab-initio calculations have been performed with density functional theory (DFT) and linear-response time-dependent DFT using ABINIT and the dp-code [2,3]. By direct comparison of experimental spectra and ab-initio calculations, we address the following questions:
(i) How do high-energy plasmons in MoS2 monolayers and multilayers behave for different momentum transfer? (ii) How do electron-energy loss spectra of MoS2-graphene heterostructures differ from the spectra of the bare monolayers?
[1] Kaiser et al., Ultramicroscopy 111, 1246 (2011)
[2] Gonze et al., Comp. Mat. Sci. 25, 478 (2002)
[3] Olevano, Reining, Sottile, http://www.dp-code.org (1998)