Structural precursor to the metal-insulator transition in V2O3

The temperature dependence of the local structure of V2O3 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 V2O3. 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.