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TT: Fachverband Tiefe Temperaturen

TT 54: Graphene: Electronic structure, excitations, etc. (joint session O/TT)

TT 54.7: Talk

Wednesday, March 11, 2026, 16:30–16:45, HSZ/0204

Proximity-induced electronic states in epitaxial graphene/SiC (0001) via Sn intercalation — •Huu Thoai Ngo¹, Zamin Mamiyev¹, Niklas Witt^2,3, Tim Wehling², and Christoph Tegenkamp¹ — ¹Solid Surface Analysis, Institute of Physics, Chemnitz University of Technology, Chemnitz, Germany — ²Institute of Theoretical Physics & Centre for Ultrafast Imaging, University of Hamburg, Hamburg, Germany — ³Institute for Theoretical Physics and Astrophysics, University of Würzburg, Würzburg, Germany

Intercalation of heavy elements at the buffer layer/SiC interface is an effective route to decouple it from the substrate while tailoring its electronic properties, for example, energy gap opening [1] and Mott insulating states [2]. In this work, we investigate the Sn-intercalated buffer layer using low-temperature STM/STS, supplemented by SPA-LEED, and DFT calculations. By precisely controlling the intercalation process, we obtain two distinct Sn phases beneath graphene: Sn(1x1) that induces Kekulé-O distortion, and honeycomb-Sn structure that gives rise to Moiré patterns. Remarkably, our STS results reveal a gap opening in Kekulé-O graphene due to Sn-induced sublattice symmetry breaking. In contrast, the honeycomb-Sn phase exhibits Mott insulating states. These findings demonstrate how Sn intercalants modify the structural and electronic properties of graphene at both nano- and microscale. [1] Ghosal, Tegenkamp, C. et al. Phys. Rev. Lett. 129, 116802 (2022). [2] Ghosal, Tegenkamp, C. et al. Phys. Rev. B 111, 235426 (2025).

Keywords: Epitaxial graphene/SiC; sublattice symmetry breaking; Kekulé-distorted graphene; Mott insulator; Intercalation