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O: Fachverband Oberflächenphysik
O 90: Electronic structure of surfaces: Spectroscopy, surface states IV
O 90.2: Talk
Thursday, March 15, 2018, 10:45–11:00, MA 042
Manipulating electron scattering resonances in graphene — •Maxim Krivenkov, Dmitry Marchenko, Jaime Sánchez-Barriga, Oliver Rader, and Andrei Varykhalov — Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, D-12489 Berlin, Germany
Scattering resonances were recently predicted to exist above the vacuum level of two-dimensional (2D) materials [1]. These resonances influence transmission of low-energetic electrons and should appear in photoemission experiments as strongly dispersive features of suppressed intensity. We were able to observe and systematically study these states in graphene by using angle-resolved photoemission spectroscopy. To investigate whether the resonances can be manipulated we explored three routes: growth of graphene on chemically diverse substrates - Ir(111), Bi/Ir, and Ni(111), enhancement of superlattice potential by Ir nanodots [2] and switching of hybridization type in graphene from sp2 to sp3 by hydrogenation. While strength of the chemical interaction with the substrate had almost no effect on the dispersion of the resonances, their energy varies with the magnitude of charge transfer from/to graphene. In contrast, deposition of superlattice of Ir nanodots as well as hydrogenation of graphene eliminate the resonances completely. Our results provide the ways of tuning optoelectronic properties of 2D materials with a graphene-like structure.
[1] V. U. Nazarov et al., Phys. Rev. B 87, 041405(R) (2013);
[2] M. Krivenkov et al., Appl. Phys. Lett. 111, 161605 (2017).