Soft X-ray absorption study of (Nd1.05−xPrx)Ba1.95Cu3O7 using synchrotron radiation

O K-edge and Cu L23-edge X-ray-absorption spectra for the series of (Nd1.05−xPrx)Ba1.95Cu3O7 compounds with x=0.0–0.5 were measured to investigate how the variation of hole states related to the superconductivity. Near the O 1s edge, the prepeaks at ∼527.6 and ∼528.3 eV are ascribed to transitions into O 2p hole states within the CuO3 ribbons and the CuO2 planes, respectively. As deduced from O 1s X-ray absorption spectra, the O 2p hole concentrations in the CuO2 planes and the CuO3 ribbons decrease monotonically with increasing the Pr doping. The present results clearly demonstrate that the suppression of superconductivity upon substituting Pr into the (Nd1.05−xPrx)Ba1.95Cu3O7 system results predominantly from the hole depletion effect.