H. Katayama-Yoshida

Evidence from angle-resolved resonant photoemission for oxygen-2p nature of the Fermi-liquid states in Bi2CaSr2Cu2O8

It has been generally accepted that a strong on-site Coulomb repulsion of the Cu 3d electrons dominates the electronic structure of the high-transition-temperature (high-Tc) superconductors. The on-site Coulomb repulsion has been evaluated as 6–7 eV, comparable with the valence-band width1,2. This strong correlation is thought to cause the Cu 3d electrons to be localized as in a Mott insulator, and doped holes may be transferred to oxygen sites, as the charge transfer energy is small compared with the correlation energy. These doped holes yield a substantial density of states at the Fermi level, characteristic of metals. There has been great effort to find and characterize the electronic states at the Fermi level, because these states relate directly to the mechanism of the high-Tc superconductivity by providing Cooper pairs below Tc. Here we report the first direct evidence for the dominant oxygen-2p nature of the Fermi-liquid state in the high-Tc superconductor, obtained using the technique of angle-resolved resonant photoemission.

Electronic excitations in Bi2Sr2CaCu2O8: Fermi surface, dispersion, and absence of bilayer splitting

From a detailed study, including polarization dependence, of the normal state angle-resolved photoemission spectra for Bi2Sr2CaCu2O8, We find only one CuO2 band related feature. All other spectral features can be ascribed either to unklapps from the superlattice or to shadow bands. Even though the dispersion of the peaks looks like band theory, the line shape is anomalously broad and no evidence is found for bilayer splitting. We argue that the dip feature in the spectrum below T-c arises not from bilayer splitting, but rather from many-body effects.

Direct observation of particle-hole mixing in the superconducting state by angle-resolved photoemission

Particle-hole (

Impurity-state-like nature of Fermi-liquid states in Bi2Sr2CaCu2O8 observed by photoemission and x-ray absorption

pensuremath{-}h

17O NMR study of YBa2Cu3O7−δ (Tc=92 K)

) mixing is a fundamental consequence of the existence of a pair condensate. We present direct experimental evidence for

Lattice dynamics of black phosphorus

pensuremath{-}h

Angle-resolved photoemission study of nonsuperconductive Bi2Sr2Ca0.4Y0.6Cu2O8

mixing in the angle-resolved photoemission (ARPES) spectra in the superconducting state of

De Haas-van Alphen measurement of YBa2Cu3O7

{mathrm{Bi}}_{2}{mathrm{Sr}}_{2}mathrm{Ca}{mathrm{Cu}}_{2}{mathrm{O}}_{8+ensuremath{delta}}

Determination of the symmetry of the 3d9L states by polarized CuL3XAS spectra of single crystal YBa2Cu3O≈6.9

. In addition to its pedagogical importance, this establishes unambiguously that the gap observed in ARPES is associated with superconductivity.

Comparative photoemission study of RbxC60, RbxC70 and RbC8. A pseudo-gap at the Fermi level in the fulleride

Abstract Photoemission and X-ray absorption spectroscopy have been performed on Bi 2 Sr 2 Ca 1− x Y x Cu 2 O 8 in which the hole concentration is controlled by the ratio between Ca and Y atoms. It was found that the density of electronic states at the Fermi level gradually increases as the hole concentration with almost no rigid shift of the electronic structure with respect to the Fermi level. This suggests that the electronic states at the Fermi level (Fermi-liquid states) would not be simple one-electron states but be a kind of impurity states produced through the strong hybridization between doped O2p hole orbitals and empty Cu3d orbitals.