Soft x-ray absorption spectroscopy studies of doped Pr-containing cuprates

Using high-resolution O K-edge x-ray absorption near-edge-structure (XANES) spectroscopy, unoccupied states of the (formula presented) (formula presented) thin films and polycrystalline (formula presented) (formula presented) as well as (formula presented) samples (formula presented) Dy, Gd, and Sm) are investigated. In (formula presented) hole numbers in the (formula presented) planes decrease significantly with increasing Pr doping level. Hole carriers generated via Ca doping in (formula presented) are directed predominantly into both the Zhang-Rice and Fehrenbacher-Rice (FR) states, while those in the (formula presented) ribbons remain almost unchanged with Ca substitution. In (formula presented) the hole content in the (formula presented) planes decreases monotonically with increasing ionic size of the (formula presented) ions, confirming the hole depletion effect based on the (formula presented) hybridization. We demonstrate the spectroscopic evidence of the existence of the FR states. The present XANES results provide a deeper understanding of the nature of hybridization and the origin of the ionic size effect.