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O: Fachverband Oberflächenphysik

O 30: Poster: Proximity Effects in Epitaxial Graphene

O 30.2: Poster

Dienstag, 19. März 2024, 12:30–14:30, Poster A

Nanoscopic transport measurements on intercalated epitaxial graphene — •Andreas Cordier, Markus Gruschwitz, Tim Güldenpfennig, and Christoph Tegenkamp — Institut für Physik, TU Chemnitz, Chemnitz, Germany

To further enhance the electronic properties of graphene, intercalation experiments are currently performed in mayn groups. Electronic transport experiments are a direct way to probe the electronic properties. However, the intercalation is often kinetically limited, thus the intercalated areas are inhomogeneous on a nm-scale. Moreover, the buffer layer/SiC(0001) surfaces also exhibit steps on a µm-scale, which further introduces anisotropy to the system. In order to account for these imperfections, we performed nanoscopic 4ppSTM transport measurements, varying the tip distances and geometry.

We realized tip configurations on single terraces as well as across many terraces, thus revealing 2D/1D/2D transport signatures, while increasing the tip distances. Moreover, using square tip configurations, the rotation of this configuration with respect to the step direction, allowed us to determine the anisotropy, which is as high as 2500. The analysis of these results allowed us to deduce the conductivity of the terraces from the conductance which amounts to σ = 600 kS/m. These experiments experimental taken at room temperature are supported by finite element simulations. Furthermore a metal-insulator transition has been found at 100K that we ascribe to the formation of a band gap in graphene, e.g. due to the induction of spin-orbit coupling in graphene by the intercalated Pb.

Keywords: Graphene; Pb Intercalation; surface transport; STM