Controlled-valence properties ofLa1−xSr

Abstract

The controlled-valence properties of La& "Sr"Fe03 and La& "Sr"Mn03 are studied by means of softx-ray absorption spectroscopy. A comparison between the transition-metal 2p spectra and atomicmultiplet calculations is used to determine the 3d count. The 0 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 LaFe03 is mainly 3d' and becomes 3d'L (where L denotes a ligand hole) in the Lal "Sr"Fe03 series for low Sr concentration. The main component of the ground state of LaMn03 is 3d and becomes a mixture of 3d' and 3d L in the Lal "Sr"Mn03 series. The trends in controlledvalence properties of similar oxides across the transition-metal series can be rationalized within the framework of the Zaanen-Sawatzky-Allen model.

Electronic states ofRFe2O4(R=Lu,Yb,TmLafuerza1, García2, Subı́as3 et al. 2014Phys. Rev. B10241View full textAdd to dashboardCite

“…showing a minimum influence of the type of R +3 . On the contrary, the XANES spectrum of LuFeCoO 4 is markedly different, and its line shape is very similar to that shown by iron oxides with formal valence Fe +3 like LaFeO 3 [54] and α-Fe 2 O 3 [55]. Besides, the XANES of LuFeCoO 4 at the Co L 2,3 edges agrees with that of compounds with formal valence Co 2+ [56].…”

Competing interactions in ferromagnetic/antiferromagnetic perovskite superlattices

“…The ground state of the LSFO system for small Sr doping (x<0.5) is the Fe 3+ -ligand hole state. [29] In accordance, the electrons involved in the charge transfer go to states of primarily oxygen character and no significant difference is observed in the Fe XA spectra for any sample.…”

“…These equally-strained solid solution and LSFO films are used as ions. [29,30] Due to the uniform Sr doping level, the change in the Mn 3+ /Mn 4+ ratio is not expected to be related to A-site chemical doping effects. Alternatively, a charge transfer involving an electron transferring from the LSMO layers to LSFO layers (Mn 3+ → Mn 4+ ) across the interface as proposed by Kumigashira and coworkers [31] might be expected.…”

Strain-Engineered Oxygen Vacancies in CaMnO3 Thin Films

“…Spin-orbit coupling splits the transition-metal L2,3 edge into two components, L2 and L3, corresponding to the 2p1/2 → 3d and 2p3/2 → 3d transitions respectively 25,26 . The most striking evidence of the changes in the Mn valence state towards Mn 3+ is observed with the systematic shift of the L2 and L3 spectral weights towards lower photon energies [26][27][28][29] as a function of increasing strain. The spectral shift is due to changes in the electrostatic energy at the Mn site driven by the decrease in the 3d count, which leads to shifts of both the core level and the final-state wavefunctions 27,30 .…”