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Electronic, magnetic, and structural properties of pure and V-doped CrO were extensively investigated utilizing density functional theory. Usually, pure CrO is a half-metallic ferromagnet with conductive spin majority species and insulating spin minority species. This system remains in its half-metallic ferromagnetic phase even at 50% V-substitution for Cr within the crystal. The V-substituted compound CrVO encounters metal-insulator transition upon the application of on-site Coulomb repulsion U = 7 eV preserving its ferromagnetism in the insulating phase. It is revealed in this study that Cr-V charge ordering accompanied by the transfer of the single V-3d electron to the Cr-3dt orbitals triggers metal-insulator transition in CrVO. The ferromagnetism of CrVO in the insulating phase arises predominantly due to strong Hund's coupling between the occupied electrons in the Cr-t states. Besides this, the ferromagnetic Curie temperature (T) decreases significantly due to V-substitution. Interestingly, a structural distortion is observed due to tilting of CrO or VO octahedra across the metal-insulator transition of CrVO. Graphical abstract The V-doped compound CrVO is found a half-metallic ferromagnet (HMF) in the absence of on-site Coulomb interaction (U). This HMF behavor maintains up to U = 6 eV. Eventually, this system encounters metal-insulator transition (MIT) upon the application of U = 7 eV with a band gap of E ~ 0.31 eV. Nevertheless, applications of higher U widen the band gaps. In this figure, calculated total (black), Cr-3d (red), V-3d (violet), and O-2p (blue) DOS of CrVO for U = 8 eV are illustrated. The system is insulating with a band gap of E ~ 0.7 eV.

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The total energy, magnetic moment, density of states and energy band structures of CrO 2 in the high pressure cubic CaF 2 (Fm-3m)-type structure are investigated for the first time by using first principles electronic structure calculations based on density functional theory in the local spin density approximation (LSDA) as well as using LSDA + U method. It is revealed from the present study that CrO 2 is a ferromagnetic nearly half-metal in the LDA calculation due to almost occupied Cr-3de g orbitals in the spin majority species and a tiny electron contribution at the Fermi level (E F) for spin minority species. This compound encounters metal-insulator transition (MIT) upon the application of Hubbard-type Coulomb repulsion U = 1 eV. Ferromagnetism is preserved in this transition. Application of U increases the electron correlation, which polarizes e g orbitals far below E F for spin majority channel while in the spin minority channel e g orbitals are polarized well above E F , resulting in opening of a band gap (E g ∼ 1.05 eV) in the vicinity of E F. Coulomb repulsion increases hybridization between occupied Cr-3de g and O-2p orbitals, which induces ferromagnetism both in half-metallic and insulating phases of cubic CrO 2 .