Epitaxial 2D Pb-layers proximitized to monolayer graphene

Selective intercalation into the buffer layer/SiC(0001) interface can realize atomically sharp interface layers near epitaxial graphene that

resemble novel 2D heterosystems. High-Z elements are interesting candidates, not only because they are expected to host Dirac fermions, but

also because spin effects are expected in graphene.

Intercalation of Pb leads to the formation of different phases, which we have studied in detail among others using scanning tunneling microscopy. As recently shown, intercalated Pb bilayers form nanostripes under graphene and show fingerprints of plumbene. These Pb layers are rotated with respect to graphene, which breaks the sublattice symmetry and is associated with an electronic gap in graphene [1]. Hexagonally arranged bubble-like structures with an average size of 2.3 nm were also found. Scanning tunneling spectroscopy (STS) again revealed the formation of mini-gaps in the 2D heterosystem. Spatially resolved

mapping of the electronic structure also clearly showed the existence

of a network of edge states around the edges of the bubbles. Moreover, the densely-packed Pb layer also efficiently minimizes the doping influence by the SiC substrate, both from the surface dangling bonds and the SiC surface polarization, giving rise to charge-neutral monolayer graphene. [2].

[1] C. Ghosal et al., PRL 129, 116802 (2022)

[2] P. Schädlich et al. Adv. Mat. Int. 10, 2300471 (2023)