Local symmetry breaking in paramagnetic insulating (Al,V)2O3 -: art. no. 085119

The local structure of (Al0.06V0.94)(2)O-3 in the paramagnetic insulating (PI) and antiferromagnetically ordered insulating (AFI) phase has been investigated using hard and soft x-ray absorption techniques. It is shown that (1) on a local scale, the symmetry of the vanadium sites in both the PI and AFI phases is the same and (2) the vanadium-3d-oxygen-2p hybridization, as gauged by the oxygen 1s absorption edge, is the same for both phases, but distinctly different from the paramagnetic metallic phase of pure V2O3. These findings can be understood in the context of a recently proposed model which relates the long-range monoclinic distortion of the antiferromagnetically ordered state to orbital ordering, if orbital short-range order in the PI phase is assumed. The measured anisotropy of the x-ray absorption spectra is discussed in relation to spin-polarized density functional calculations.