2003/09/13 by Arata Tanaka · 1 citation
Chemical Engineering · Materials Science · Physics and Astronomy · #Atomic orbital #Catalysis and Oxidation Reactions #Chemical and Physical Properties of Materials #Coulomb #Exchange interaction #Ground state #Hubbard model #Lattice (music) #Mott insulator #Mott transition #Phase transition #Transition Metal Oxide Nanomaterials #cond-mat
paper · pdf · doi:10.1143/jpsj.72.2433
5 pages, 5 figures, to be published in J. Phys. Soc. Jpn. Vol. 72 No. 10
arxiv created 2003/09/13 · openalex publication_date 2003/10/15 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The metal-insulator transition in VO2 was investigated using the three-band Hubbard model, in which the degeneracy of the 3d orbitals, the on-site Coulomb and exchange interactions, and the effects of lattice distortion were considered. A new scenario on the phase transition is proposed, where the increase in energy level separation among the t2g orbitals caused by the lattice distortion triggers an abrupt change in the electronic configuration in doubly occupied sites from an S=1 Hund's coupling state to a spin S=0 state with much larger energy, and this strongly suppresses the charge fluctuation. Although the material is expected to be a Mott-Hubbard insulator in the insulating phase, the metal-to-insulator transition is not caused by an increase in relative strength of the Coulomb interaction against the electron hopping as in the usual Mott transition, but by the level splitting among the t2g orbitals against the on-site exchange interaction. The metal-insulator transition in Ti2O3 can also be explained by the same scenario. Such a large change in the 3d orbital occupation at the phase transition can be detected by linear dichroic V 2p x-ray absorption measurements.