High-resolution angle-resolved photoemission study of bulk electronic states in image Original Research Article

We have studied low-energy electronic structure of YBa2Cu3O7-δYBa2Cu3O7-δ using high-resolution angle-resolved photoemission spectroscopy (ARPES). By carefully tuning photon energy and polarization of incident light, we identified five different bands in the vicinity of the Fermi level, those are surface-bilayer-derived bonding and antibonding bands, their bulk counterparts, and CuO-chain-derived band, respectively. The surface bands show metallic property reflecting highly overdoped character, while bulk bands show signature of a dx2-y2dx2-y2-wave superconducting gap opening. The present ARPES result suggests the universality of the bulk electronic states in bilayer high-TcTc superconductors.