Berlin 2024 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 94: Focus Session: Proximity Effects in Epitaxial Graphene I

O 94.10: Vortrag

Donnerstag, 21. März 2024, 17:45–18:00, MA 141

Evidence of Sn-induced Mott states coupled to Dirac electrons in epitaxial graphene — •Chitran Ghosal¹, Zamin Mamiyev¹, Siheon Ryee², Niklas Witt^2,3, Tim Wehling^2,3, and Christoph Tegenkamp¹ — ¹Institute of Physics, Technische Universität Chemnitz, Reichenhainer Str. 70, Germany — ²I. Institute of Theoretical Physics, University of Hamburg, Notkestraße 9-11, 22607 Hamburg, Germany — ³The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22607 Hamburg, Germany

The adsorption of 1/3 ML of Sn on SiC(0001) was shown to reveal a robust 2D Mott state. In this work we studied the electronic structure of intercalated Sn below the buffer layer on SiC(0001) coming along with the formation of n-type doped graphene. SPALEED clearly revealed new √3-reconstruction spots after the intercalation process. By means of EELS and STS we analyzed in detail the electronic structure of this heterostructure. We found strong evidence of a hybridization between Sn-induced Mott states and the graphene π-bands. This leads to a gap opening of around 200 meV at the Dirac point. Moreover, a new state at around 1.2 eV emerged which we assign to the upper Hubbard band. The formation of narrow bands is supported by EELS measurements, showing besides the sheet plasmon also a pronounced interband transition at 1.5 eV. Combined DFT and dynamical mean field theory calculations support the emergence of strong Mott Hubbard correlations in this system. The emerging correlation effects show a pronounced stacking and charge transfer dependence and lead to spectral functions in good agreement with the experiments.

Keywords: Intercalation; Proximity Effects; Graphene; 2D materials; Correlation