2D interlayers

The confinement of materias between graphene and SiC can lead to 2D layers with unique properties. We have investigated the intercalation of a monolayer of Pb, which leads to a complex (10x10) superstructure with respect to graphene but is closely related to a (1x1) superstructure with respect to the SiC. The intercalation of Pb leads to an almost charge neutral graphene with a p-doping level as low as 5x10⁹ cm^-2. The exact doping depends on the sample temperature. Due to freezing of the SiC charge carriers at low temperature the p-type doping increases with decreasing temperature.

The interlayer Pb bands can be modeled by a parabolic free-electron dispersion. However, our high-resolution ARPES measurements and DFT calculations show a number of deviations form a parabolic band structure like avoided crossings. Polarization dependent measurements showed that the Pb bands close to the Fermi energy show mostly out-of-plane p_z character, which suggests a possible coupling of the Pb states to the graphene π-bands.

Publications:

B. Matta, P. Rosenzweig, C. Polley, U. Starke, K. Küster, Nanoscale, 17, 19317 (2025), Charge transfer between van der Waals coupled metallic 2D layers.
B. Matta, P. Rosenzweig, K. Küster, C. Polley, U. Starke, Phys. Rev. B 111, 155435 (2025). Pb-intercalated epitaxial graphene on SiC: Full insight into band structure and orbital character of interlayer Pb, and charge transfer into graphene.
P. Schädlich, C. Gosal, M. Stettner, B. Matta, S. Wolff, F. Schölzel, P. Richter, M. Hutter, A. Haags, S. Wenzel, Z. Mamiyev, J. Koch, S. Soubatch, P. Rosenzweig, C. Polley, F. S. Tautz, C. Kumpf, K. Küster, U. Starke, T. Seyller, F. C. Bocqet, C. Tegenkamp, Adv. Mater. Interfaces 2300471 (2023). Domain boundary formation within an intercalated Pb monolayer featuring charge-neutral epitaxial graphene.
B. Matta, P. Rosenzweig, O. Bolkenbaas, K. Küster, U. Starke, Phys. Rev. Research 4, 023250 (2022). Momentum microscopy of Pb-intercalated graphene on SiC: charge neutrality and electronic structure of interfacial Pb.