Density Functional Study Of Metal To Half-metal Transition In The Rutile Vanadium Dioxide VO2
Volume 3, Issue 5, Page 351-355, Year 2018 | DOI: 10.5185/amp.2018/407
Keywords: Metal insulator transition (MIT), half-metal, coulomb repulsion, crystal structure of VO2”, transition metal oxides.
Abstract: First principles electronic structure calculations implemented in the density functional theory have been employed to investigate the electronic and magnetic properties of VO2 in the high temperature rutile structure with tetragonal P42/mnm symmetry. The system is a nonmagnetic metal in the absence of Hubbard- type Coulomb interaction U. It is revealed in this study that the three V-t2g states are degenerate due to partial electron filling which is responsible for orbital fluctuations between them. Due to these orbital fluctuations and sharing of single 3d electron by V-t2g states, no band gap opens in the close vicinity of Fermi level. Nevertheless, upon the application of U = 4 eV, the system encounters metal to half-metal transition without any structural phase transitions exhibiting ferromagnetic behaviour. In spin up channel, dyz and dxz states remain degenerate while dx2- y2 state is more occupied but are strongly hybridized with O-2p orbitals resulting ferromagnetism. In spin down channel, Fermi level is suppressed below the V-t2g bands while V- 4s state is shifted above the Fermi level causing opening of a band gap near the Fermi level. Copyright © 2018 VBRI Press.