Effect of K doping on the quasifreestanding graphene formed on Au/Ni(111): Density-functional calculations

Abstract

We investigated the atomic and electronic structure of the K-adsorbed graphene/Au/Ni(111) surface by using density-functional calculations. The role of the K adsorbates is verified as a simple donor: the adsorption of K induces a rigid shift of the graphene pi bands with preserving the quasifreestanding Dirac-cone shape. The pi character of the Dirac-cone bands, however, undergoes some weakening due to the hybridization with Ni d bands, especially in the energy range of 0.5-0.8 eV (0.1-0.3 eV) below the Fermi level for the majority (minority) spin band structure. This weakening of the pi character could possibly account for the reduced photoemission intensity of the Dirac cone, which was experimentally reported as a band gap of 0.6 eV.