The temperature dependence of the local structure of ${\mathrm{V}}_2{\mathrm{O}}_3$ in the vicinity of the metal-to-insulator transition (MIT) has been investigated using hard x-ray absorption spectroscopy. It is shown that the vanadium pair distance along the hexagonal $c$ axis changes abruptly at the MIT as expected. However, a continuous increase of the tilt of these pairs sets in already at higher temperatures and reaches its maximum value at the onset of the electronic and magnetic transition. These findings confirm recent theoretical results which claim that electron-lattice coupling is important for the MIT in ${\mathrm{V}}_2{\mathrm{O}}_3$. Our results suggest that the distortion of the symmetry of the basal plane plays a decisive role for the MIT and orbital degrees of freedom drive the MIT via changes in hybridization.

• Received 17 November 2005

DOI:https://doi.org/10.1103/PhysRevB.73.144106