The backside of graphene: functionalization by intercalation

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As atomic layer material, the atoms of graphene are at the same time front- and backside surface atoms. Therefore, the properties of graphene depend crucially on its environment. Only if bounded on both sides by vacuum, its properties come close to the theoretical predictions for the pure, suspended material. However, the ease by which graphene is affected through contact with other materials is one of its unique features and defines an integral part of its potential for applications. In this proposal we will use intercalation, the insertion of atomic layers in between the backside of graphene and its substrate, as a tool to change its properties and its interaction with the environment on its frontside. The investigations will rely on an all in situ surface science approach to grow, modify and analyze structurally perfect graphene. Through well-defined experiments unambiguous theoretical modeling will be possible.Intercalation provides a flexible means to drastically modify the chemical potential of the Dirac electrons, providing changes an order of magnitude larger as available by external gating. As a specific tool for our research, we will use intercalation patterns providing a strong local variation of the doping level. We will explore how extreme p- and n-doping changes the nature of the chemical interaction of ionic adsorbates, organic molecules and radicals with graphene. New, hitherto unobserved phenomena in graphene are expected, such as a doping dependent molecular switching, doping dependent ordering of adatoms, or writing of chemical patterns predefined by intercalation patterns. Graphene has been proven to be an excellent spin conductor. The application potential for spintronics would greatly increase, if it would be possible to induce spin polarization in graphene. This perspective has already triggered a large effort to induce a spin-split Dirac cone through contact with ferromagnetic 3d materials. However, the strong hybridization of the d-electrons with the pi-electronic system of graphene appears to limit the applicability of this concept. To achieve a spin-split and intact Dirac cone, we explore here the use of up now uninvestigated rare earth metal intercalation layers, also in combination with ferromagnetic layers.