A DFT Study of the Electronic, Magnetic and Structural Properties of Rutile VO2

The electronic, magnetic and structural properties of rutile VO2 are investigated by employing density functional theory (DFT). In the high-temperature tetragonal structure (I4(2)/mnm), VO2 is a nonmagnetic metal. All the V-t(2g) states are partially occupied by the single V 3d electron, which is responsible for the metallic behavior of VO2. The electronic and magnetic properties of rutile VO2 change significantly upon the application of on-site Coulomb interaction U. The system undergoes a first step transition from nonmagnetic metal to a ferromagnetic metallic phase at U = 1 eV. Eventually, VO2 encounters a metal to half-metal transition for U = 2 eV, preserving ferromagnetism in the half-metallic phase. From this study, the polarization of V-3d electrons arising from the electron correlation due to the application of U is accounted for metal to half-metal transition in VO2. The combined effect of p-d hybridizations and the anti-ferromagnetic coupling of V and O atoms is responsible for the ferromagnetism of half-metallic VO2. Nevertheless, an insignificant structural distortion is observed across the metal to half-metal transition.