Berlin 2015 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 117: Graphene: Intercalation (jointly with O, HL)

TT 117.2: Talk

Friday, March 20, 2015, 10:45–11:00, MA 041

Intercalation of Gadolinium underneath graphene on SiC(0001) — •Stefan Link, Stiven Forti, Alexander Stöhr, and Ulrich Starke — Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany

Investigating the properties of graphene in a highly doped state, such that the Fermi level reaches a saddle point of it’s electronic bands is an on-going field. Superconductivity could be one potential effect in this regime. Functionalization with highly reactive species such as alkali and/or earth alkali atoms has been pursued for strong doping effects. However, such systems are prone to fast degradation by environmental influences which needs to be circumvented for any kind of application.

Here, we present a method of doping graphene to such levels and simultaneously making the system stable to temperatures higher than 1000^∘C as well as to air exposure. This was achieved by the intercalation of Gadolinium atoms underneath the so-called buffer layer on SiC(0001), i.e., the carbon rich (6√3×6√3)R30^∘ reconstruction of this surface. Significant hybridization effects of the graphene π-bands with the adatom states are observed in the ARPES data. In addition, evidence for strong electron-phonon scattering is visible. Spectroscopic weight appears in the measurements completely interlinking two Dirac cones through the M-point, thus indicating the presence of an electronic topological transition (ETT).