Berlin 2024 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

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

O 94.5: Vortrag

Donnerstag, 21. März 2024, 16:15–16:30, MA 141

Mott states under cover: Silicon intercalation of epitaxial graphene — •Niclas Tilgner, Zamin Mamiyev, and Thomas Seyller — TU Chemnitz Institut für Physik

Mott-Hubbard bands are well known from different superstructures on SiC(0001). Typical examples are the siliconrich (3 × 3) and (√3×√3)R30^∘ reconstruction, but also the unreconstructed (1 × 1) surface. In all cases the electrons occupying the dangling bonds show a non-negligible interaction among themselves, which gives rise to a Mott-Hubbard metal-insulator transition. The dispersion and the energetic splitting of the upper and lower Hubbard band was found to scale with the distance between the dangling bonds and the dielectric properties of the environment, respectively. It could be achieved to prepare an analogous system underneath graphene by intercalation of silicon. The talk focuses on the major results, which were acquired. Experiments using diffraction techniques (LEED, SPA-LEED) allow the evaluation of the silicon arrangement, that is found to consist of different patches with (√3×√3)R30^∘, (2 × 2) and (3 × 3) ordering. Furthermore, investigations of the prepared samples with photoemission techniques (ARPES, XPS) reveal several surface states, which can partly be attributed to the dangling bonds of the silicon adatoms and therefore to one of the Hubbard bands. Unintuitively, no avoided crossing with the Dirac cone is observed. Possible reasons for this circumstance will be discussed.

Keywords: graphene; intercalation; silicon; Mott-Hubbard states; photoemission