Band gap opening in graphene by hybridization with Au (001) reconstructed surfaces

Au(001) surfaces exhibit a complex reconstructed structure $[\mathrm{Hex}\ensuremath{-}\mathrm{Au}(001)]$ comprising a hexagonal surface and square bulk lattices, yielding a quasi-one-dimensional corrugated surface. When graphene was grown on this surface, the periodicity of the corrugated surface was predicted to change the electronic structure of graphene, forming bandgaps and new Dirac points. Furthermore, the graphene--Au interface is promising for bandgap generation and spin injection due to band hybridization. Here, we report the angle-resolved photoemission spectroscopy and density functional calculation of graphene on a $\mathrm{Hex}\ensuremath{-}\mathrm{Au}(001)$ surface. The crossing point of the original and replica graphene \ensuremath{\pi} bands showed no bandgap, suggesting that the one-dimensional potential was too small to modify the electronic structure. A bandgap of 0.2 eV was observed at the crossing point of the graphene \ensuremath{\pi} and Au $6sp$ bands, indicating that the bandgap is generated using hybridization of the graphene \ensuremath{\pi} and Au $6sp$ bands. We discussed the hybridization mechanism and concluded that the R30 configuration between graphene and Au and an isolated electronic structure of Au are essential for effective hybridization between graphene and Au. We anticipate that hybridization between graphene \ensuremath{\pi} and Au $6sp$ would result in spin injection into graphene.