On the metal–insulator transition in vanadium dioxide

The conductivity σ of vanadium dioxide (VO2) drops at a metal–insulator transition by four orders of magnitude due to the structural change between tetragonal and monoclinic crystals. In order to elucidate this conductivity drop, we introduce the semiclassical equation of motion to describe the dynamics of the conduction electron (wave packet), where the existence of a k-vector k is prerequisite for the conduction. We showed that the periodicity using the non-orthogonal bases does not legitimize the electron dynamics in solids. The theory suggests that the decrease in the dimensionality of the k-vectors due to the structural change is the cause of the conductivity drop.

► The existence of k-vectors is prerequisite for the electrical conduction. ► The conductivity drop at the metal–insulator transition in VO2 arises directly from the lattice-structure transformation. ► The decrease in the dimensionality of the k-vectors going from the tetragonal to monoclinic crystal causes the conductivity drop.