COMPARATIVE SOFT-X-RAY RESONANT-PHOTOEMISSION STUDY ON BI2SR2CACU2O8, CUO, AND CU2O

Strong O 1s and Cu 2p resonant enhancements are observed in the valence-band photoemission spectra of Bi2Sr2CaCu2O8, CuO, and Cu2O. The results can be accounted for by a model Hamiltonian with similar parameters but different band filling. The O 1s (Cu 2p) resonant enhancements are found to be dominated by local O 2p4 (Cu 3d8) final states reached via local intra-atomic processes; interatomic O-to-Cu resonance processes are found to play only a minor role. It is demonstrated that enhancements observed at 0-1.5 eV binding energies in angle-resolved photoemission of Bi2Sr2CaCu2O8 with the photon energy tuned at 18 eV cannot be attributed to an O 2s resonance effect.