We have studied the effect of dynamical correlations on the electronic structure of single Co adatoms on graphene monolayers with a recently developed method for nanoscopic materials that combines density-functional calculations with a fully dynamical treatment of the strongly interacting $3d$ electrons. The coupling of the $\text{Co}3d$ shell to the graphene substrate and hence the dynamic correlations are strongly dependent on the orbital symmetry and the system parameters (temperature, distance of the adatom from the graphene sheet, and gate voltage). When the Kondo effect takes place, we find that the dynamical correlations give rise to strongly temperature-dependent peaks in the $\text{Co}3d$ spectra near the Fermi level. Moreover, we find that the Kondo effect can be tuned by the application of a gate voltage. It turns out that the position of the Kondo peaks is pinned to the Dirac points of graphene rather than to the chemical potential.

• Received 28 June 2010

DOI:https://doi.org/10.1103/PhysRevB.82.085423