Abstract
We report an x-ray photoemission spectroscopy (XPS) and x-ray absorption spectroscopy (XAS) study on VTiO ( = 0.0, 0.3, and 4.0) in which the metal-insulator transition (MIT) and the tetragonal-to-monoclinic structural transition show different responses against the Ti doping. The spectral change of V 2 XAS across the MIT is similar to that observed in VO, indicating that the V-V pairing is responsible for the MIT. In the insulating phase, the V 2 XPS spectra are split into the and features showing the localized character of the V 3 electrons. In addition, the V 2 XAS spectra of the monoclinic insulating phase suggest that the V-V pairing is weakened, and, instead, the -V coupling is strengthened by orbital ordering. In contrast to VO, the existence of the component in VTiO gives additional orbital instability in the insulating phase, which competes with the V-V pairing.
- Received 29 December 2010
DOI:https://doi.org/10.1103/PhysRevB.83.125112
©2011 American Physical Society