Tunable hybridization between electronic states of graphene and a metal surface

We present an approach to monitor and control the strength of the hybridization between electronic states of graphene and metal surfaces. Inspecting the distribution of the pi band in a high-quality graphene layer synthesized on Ni(111) by angle-resolved photoemission, we observe a new kink feature that indicates a strong hybridization between the pi and the d states of graphene and nickel, respectively. Upon deposition and gradual intercalation of potassium atoms into the graphene/Ni(111) interface, the kink feature becomes less pronounced, pointing at potassium mediated attenuation of the interaction between the graphene and the substrate.