The controlled-valence properties of ${\mathrm{La}}_{1\mathrm{-}\mathit{x}}$${\mathrm{Sr}}_{\mathit{x}}$${\mathrm{FeO}}_3$ and ${\mathrm{La}}_{1\mathrm{-}\mathit{x}}$${\mathrm{Sr}}_{\mathit{x}}$${\mathrm{MnO}}_3$ are studied by means of soft-x-ray absorption spectroscopy. A comparison between the transition-metal 2p spectra and atomic-multiplet calculations is used to determine the 3d count. The O 1s spectrum is used to characterize changes in unoccupied states that contain oxygen p character. The results indicate that the holes induced by substitution for both series are located in states of mixed metal 3d–oxygen 2p character. The ground state of ${\mathrm{LaFeO}}_3$ is mainly 3${\mathit{d}}^5$ and becomes 3${\mathit{d}}^5$L (where L denotes a ligand hole) in the ${\mathrm{La}}_{1\mathrm{-}\mathit{x}}$${\mathrm{Sr}}_{\mathit{x}}$${\mathrm{FeO}}_3$ series for low Sr concentration. The main component of the ground state of ${\mathrm{LaMnO}}_3$ is 3${\mathit{d}}^4$ and becomes a mixture of 3${\mathit{d}}^3$ and 3${\mathit{d}}^4$L in the ${\mathrm{La}}_{1\mathrm{-}\mathit{x}}$${\mathrm{Sr}}_{\mathit{x}}$${\mathrm{MnO}}_3$ series. The trends in controlled- valence properties of similar oxides across the transition-metal series can be rationalized within the framework of the Zaanen-Sawatzky-Allen model.

• Received 13 December 1991

DOI:https://doi.org/10.1103/PhysRevB.46.4511