Reconstructed Fermi surface in graphene on Ir(111) by Gd-Ir surface alloying

Graphene electronics covers a number of unique effects and the most intriguing ones are based on its interaction with other materials. Contact of graphene with the lattice-mismatched substrate clones the Dirac cone and gives rise to Hofstadter spectrum, while contact with the heavy/magnetic atoms realizes topological insulator phase. Here we study the electronic structure of graphene on Ir(111) with intercalated rare-earth Gd atoms by means of Angle-Resolved Photoemission Spectroscopy (ARPES). Gd intercalation results in the formation of the Gd-Ir surface alloy with the (2 × 2) superstructure, but the moire superlattice of graphene persists. Strong charge transfer from Gd atoms leads to the shifting of the Dirac cone and its replicas towards the higher binding energies while closing the u m k l a p p band gaps. The replicated Dirac cone bands cross each other near the Fermi level, that is essential for the superlattice effects application in electronics.