Electronic band structure of a two-dimensional oxide quasicrystal

Since the discovery of quasicrystals, the study of their electronic structure has been a challenging topic due to the absence of translational symmetry. Here, the valence bands of a novel two-dimensional ultrathin BaTiO${}_{3}$-derived oxide quasicrystal are determined by momentum-resolved photoelectron spectroscopy. The dispersion of the oxygen 2$p$ bands and the occupation of the Ti 3$d$ states are identified. They bridge the knowledge deriving from free-electron-like wave functions in bulk quasicrystals to that of the more localized electrons in confined dimensions.