Theory of Fano Resonances in Graphene: The Kondo effect probed by STM

Abstract

We consider the theory of Kondo effect and Fano factor energy dependence for magnetic impurity (Co) on graphene. We have performed a first principles calculation and find that the two dimensional $E_1$ representation made of $d_{xz},d_{yz}$ orbitals is likely to be responsible for the hybridization and ultimately Kondo screening for cobalt on graphene. There are few high symmetry sites where magnetic impurity atom can be adsorbed. For the case of Co atom in the middle of hexagon of carbon lattice we find anomalously large Fano $q$-factor, $q\approx 80$ and strongly suppressed coupling to conduction band. This anomaly is a striking example of quantum mechanical interference related to the Berry phase inherent to graphene band structure.