Berlin 2024 – scientific programme

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O: Fachverband Oberflächenphysik

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

O 94.9: Talk

Thursday, March 21, 2024, 17:30–17:45, MA 141

Low energy plasmons in Sn-intercalated quasi-free-monolayer-graphene — •Zamin Mamiyev and Christoph Tegenkamp — Institut für Physik, Technische Universität Chemnitz

Graphene plasmons, particularly confined within structured and sandwiched graphene, represent a fascinating area of research. They hold the potential to facilitate the manipulation of light at sub-wavelength scales while providing a platform for investigating the many-body electronic interactions. Our study focuses on low-energy plasmonic excitations in epitaxial quasi-free monolayer graphene, created through the intercalation of Sn beneath the buffer layer on 4H-SiC(0001). [1]

The quantitative examination of the sheet plasmon dispersion reveals that the Sn-induced (1×1) interface exhibits metallic properties, leading to the formation of charge-neutral graphene. The dispersion of the sheet plasmon (activated by mild doping with K) is slightly redshifted with w.r.t. epitaxial graphene (EG). On the other hand, the Sn-diluted (√3×√3) reconstruction forms intrinsically n-type doped graphene with a dispersion similar to the epitaxial monolayer graphene on the carbon buffer layer. Moreover, it appears that the dipolar coupling of longitudinal charge density fluctuations in EG to the interface layer triggers the formation of a plasmonic multipole component at higher frequencies. Our study shows that angle-resolved plasmon spectroscopy is a promising technique to investigate proximity effects of excitations in electronically weakly coupled 2D heterostructures.

[1] Z. Mamiyev and C. Tegenkamp, Surf. & Int. 34, 102304 (2022)

Keywords: Plasmon; Epitaxial graphene; Intercalation; 2D heterostructures; Proximity coupling