Hafnium intercalation between epitaxial graphene and Ir(111) substrate

We report on the change of structural and electronic properties while depositing Hf atoms onto the graphene epitaxially grown on Ir(111) substrate. We find that the Hf atoms intercalate between the graphene and its iridium host. This intercalation induces a new interface superstructure, as confirmed by scanning tunneling microscopy and low energy electron diffraction. Raman spectra reveal that the Hf-intercalated graphene shows the prominent features of intrinsic graphene. Our study suggests that the Hf intercalation acts as a buffer layer between the graphene and the Ir(111) substrate, restoring the graphenes intrinsic electronic properties.