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要旨:
The x-ray absorption spectra at the Bi-L-1 and S-K edges of LaO1-xFxBiS2 show a decrease of spectral weight close to the absorption thresholds upon F substitution for O, indicating a reduction of the unoccupied Bi 6p and S 3p states, as expected for electron doping. This doping-induced spectral weight transfer at the S-K edge is similar to the electron-doped cuprate superconductor, Nd2-xCexCuO4, but the polarization-dependent XAS spectra of LaO0.54F0.46BiS2 at the S-K edge is very different from those of Nd2-xCexCuO4 at the O-K edge, reflecting different constitution of valence electrons. We found that one-electron band structure calculations cannot describe our experimental S-K XAS spectra of LaO1-xFxBiS2, suggesting possible correlation effects for p electrons, which is important in transition metal compounds with the dominating d electrons.
