Correlation assisted metal-insulator transition in the high temperature tetragonal rutile vanadium dioxide

BISWAS, SARAJIT

Abstract

Vanadium dioxide is a nonmagnetic metal in high temperature rutile phase and undergoes metal-insulator transition (MIT) upon the application of Coulomb interaction U = 5 eV.  The insulating phase is ferromagnetic. By employing first principles electronic structure calculations implemented in the density functional theory, it has been found in the LDA approximations that dxy, dyz and dx2- y2 states are almost degenerate and are responsible for non opening of a gap in the close vicinity of Fermi level (EF). In the LDA+U approximations, strong Coulomb interactions play crucial role in the MIT of VO2 in the high temperature rutile phase. Application of Coulomb interactions increase orbital polarizations and hence static electron correlations for which dx2- y2 state becomes completely occupied  and shifted below EF whereas,  dyz and dxz states become empty and shifted above EF resulting opening of a band gap near EF. The hybridizations between occupied V-3dx2- y2 and O-2p orbitals are responsible for observed ferromagnetic behavior of VO2 in the insulating phase.

Keyword(s)

Metal insulator transition (MIT); Rutile structure; Coulomb repulsion; Crystal structure of VO2

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