Noble-metal intercalation process leading to a protected adatom in a graphene hollow site

MN Nair and M Cranney and T Jiang and S Hajjar-Garreau and D Aubel and F Vonau and A Florentin and E Denys and ML Bocquet and L Simon, PHYSICAL REVIEW B, 94, 075427 (2016).

DOI: 10.1103/PhysRevB.94.075427

In previous studies, we have shown that gold deposited on a monolayer (ML) of graphene on SiC(0001) is intercalated below the ML after an annealing procedure and affects the band structure of graphene. Here we prove experimentally and theoretically that some of the gold forms a dispersed phase composed of single adatoms, being intercalated between the ML and the buffer layer and in a hollow position with respect to C atoms of the ML on top. They are freestanding and negatively charged, due to the partial screening of the electron transfer between SiC and the ML, without changing the intrinsic n-type doping of the ML. As these single atoms decouple the ML from the buffer layer, the quasiparticles of graphene are less perturbed, thus increasing their Fermi velocity. Moreover, the hollow position of the intercalated single Au atoms might lead to spin-orbit coupling in the graphene layer covering IC domains. This effect of spin-orbit coupling has been recently observed experimentally in Au-intercalated graphene on SiC(0001) D. Marchenko, A. Varykhalov, J. Sanchez-Barriga, Th. Seyller, and O. Rader, Appl. Phys. Lett. 108, 172405 (2016) and has been theoretically predicted for heavy atoms, like thallium, in a hollow position on graphene C. Weeks, J. Hu, J. Alicea, M. Franz, and R. Wu, Phys. Rev. X 1, 021001 (2011); A. Cresti, D. V. Tuan, D. Soriano, A. W. Cummings, and S. Roche, Phys. Rev. Lett. 113, 246603 (2014).

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