Abstract
The local magnetic properties of the various atomic sites in metallic and insulating and have been determined by means of nuclear magnetic resonance. Remarkably free-spin-like paramagnetic behavior is found in metallic and , although there is not full differentiation into 3+ and 4+ charge states on the different sites. Below the metal-insulator transition, one group of ions forms nonmagnetic singlet spin pairs in the insulating phase while the remainder of the sites are paramagnetic. In the antiferromagnetic insulating state two magnetic vanadium sites with hyperfine fields 70.1 and 78.4 kOe and one nonmagnetic vanadium site are found. These results are analyzed in terms of various theoretical models, i.e., a modified Hubbard model and small-polaron model. None of the theoretical models is satisfactory.
- Received 21 September 1973
DOI:https://doi.org/10.1103/PhysRevB.9.1230
©1974 American Physical Society