Electronlike Fermi surface in bismuth cuprates determined by ARPES: Bulk versus surface photoemission

We report an extensive angle-resolved photoemission spectroscopy study of a set of quickly dispersing electronic states near the Gamma(0,0) point in B i2Sr2CaCu2-xNixOy (x<1%) single crystals at photon energy hv=38 eV. These s tates cross the Fermi surface along both the T-M and Gamma-Y directions and are outside the well-known large Fermi surface and satellite bands due to the superstructure in Bi2212. The electronic states have a strong nonmonoto nic photon energy dependence and demonstrate a symmetry different from the symmetry of the Cu-O plane. The possible origin of these electronic states is discussed. In addition, we show that the whole Fermi-surface topology in Bi2212 is photon energy dependent.