In most of the charge ordering phenomena (Fe3O4, NaV2O5, LaSr2Mn2O7, La0.5Ca0.5MnO3 etc.), the charge ordering is not complete. For example, in manganites, the Mn valence in the charge-ordered state is 3.5 +- \Delta where \Delta is about 0.2 or less. This observation is fairly general. Has anyone observed complete charge ordering where complete Mn^3+ and Mn^4+ exist? Does \Delta depend on the strength of electron correlations?
It is true that most of the charge ordering phenomena are associated with the orbital ordering as well. The problem is of course diffraction technique is not too directly sensitive either to orbital or to charge ordering. You make indirect guesses from the lattice distortion whenever the orbital ordering is also associated. The bond distances also tell you indirectly about he charge ordering and I guess you inferred complete charge ordering in Ba3NaRu2O9 from bond distances. In NaV2O5 we employed spin dynamics to extract the amount of charge ordering but again this was an indirect method. I was looking for a more direct determination of the amount of charge separation. I was wondering whether X-ray spectroscopy can give such information.
- Badges
- Science method
- Similar topics
- Methodology
- Crystallography
- X-ray Diffraction