Structural instability of the rutile compounds and its relevance to the metal-insulator transition of VO2

Abstract

The metal-insulator transition (MIT) of VO2 is discussed with particular emphasis on the structural instability of the rutile compounds toward dimerization. Ti substitution experiments reveal that the MIT is robust up to 20% Ti substitutions and occurs even in extremely thin V-rich lamellas in spinodally decomposed TiO2-VO2 composites, indicating that the MIT is insensitive to hole doping and essentially takes on a local character. These observations suggest that either electron correlation in the Mott-Hubbard sense or Peierls (Fermi-surface) instability plays a minor role on the MIT. Through a broad perspective of crystal chemistry on the rutile-related compounds, it is noted that VO2 and another MIT compound NbO2 in the family eventually lie just near the borderline between the two structural groups with the regular rutile structure and the distorted structures characterized by the formation of dimers with direct metal-metal bonding. The MITs of VO2 and NbO2 are natural consequences of structural transitions between the two groups, as all the d electrons are trapped in the bonding molecular orbitals of dimers at low temperatures. Such dimer crystals are ubiquitously found in early transition metal compounds having chain-like structures, such as MoBr3, NbCl4, Ti4O7, and V4O7, the latter two of which also exhibit MITs probably of the same origin. In a broader sense, the dimer crystal is a kind of molecular orbital crystals in which virtual molecules made of transition metal atoms with partially-filled t2g shells, such as dimers, trimers or larger ones, are generated by metal-metal bonding and are embedded into edge- or face-sharing octahedron networks of various kinds. The molecular orbital crystallization opens a natural route to stabilization of unpaired t2g electrons in crystals.

29 pages, 23 figures, 5 tables

References in corpus (8)

• Evidence for a Structurally-driven Insulator-to-metal Transition in VO2: a View from the Ultrafast Timescale
• Measurement of a solid-state triple point at the metal-insulator transition in VO2
• Orbital-assisted metal-insulator transition in VO${}_2$
• Possible valence-bond condensation in the frustrated cluster magnet LiZn2Mo3O8
• Magnetic transition and orbital degrees of freedom in vanadium spinels
• Band Jahn-Teller Instability and Formation of Valence Bond Solid in a Mixed-Valent Spinel Oxide LiRh2O4
• Spinodal Decomposition in the TiO2-VO2 System
• Classical dimers and dimerized superstructure in orbitally degenerate honeycomb antiferromagnet

Cited by in corpus (27)

• Unraveling the Mott-Peierls intrigue in Vanadium dioxide
• Magnetic-field-induced insulator-metal transition in W-doped VO2 at 500 T
• Database, Features, and Machine Learning Model to Identify Thermally Driven Metal-Insulator Transition Compounds
• Multiple crossovers and coherent states in a Mott-Peierls insulator
• Non-thermal nature of photo-induced insulator-to-metal transition in NbO${}_2$
• Regular-Triangle Trimer and Charge Order Preserving the Anderson Condition in the Pyrochlore Structure of CsW${}_2$O${}_6$
• Structural evolution and skyrmionic phase diagram of the lacunar spinel GaMo${}_4$Se${}_8$
• Flavor-wave theory with quasiparticle damping at finite temperatures: Application to chiral edge modes in the Kitaev model
• Dual Orbital Degeneracy Lifting in a Strongly Correlated Electron System
• Linear Trimer Formation by Three-Center-Four-Electron Bonding in RuP
• Fragile 3D Order in V${}_{1-x}$Mo${}_x$O${}_2$
• Complex Quasi-Two-Dimensional Crystalline Order Embedded in VO${}_2$ and Other Crystals
• Robust atomic orbital in the cluster magnet LiMoO2
• Single-site DFT+DMFT for vanadium dioxide using bond-centered orbitals
• Molecular orbital formation and metastable short-range ordered structure in VO${}_2$
• Correlation induced emergent charge order in metallic vanadium dioxide
• Molecular Orbital Electronic Instability in the van der Waals Kagome Semiconductor Nb${}_3$Cl${}_8$: Exploring Future Directions
• Dimer Crystallization Induced by Elemental Substitution in the Honeycomb Lattice of Ru1-xOsxCl3
• Soft-Chemical Synthesis, Structure Evolution, and Insulator-to-Metal Transition in a Prototypical Metal Oxide, λ-RhO${}_2$
• Reexamination of the charge-ordered dimer pattern in the spinel compound CuIr2S4 using single-crystal synchrotron x-ray diffraction
• Introduction to High-Temperature Superconductivity for Solid State Chemists
• Topological Electronic Structure and Transport Properties of the Distorted Rutile-type WO${}_2$
• Electronic Self-Organization in the β-Pyrochlore Oxide CsW2O6
• Yb 4f-Ta 5d Hybridization and Valence Evolution in Tetragonal Tungsten Bronze Ba(3-x)YbxTa5O15
• Peierls-like distortion drives anion ordering in rutile TiOF
• Current-induced successive structural phase transitions beyond thermal equilibrium in single-crystal VO2
• Metallic state in the vicinity of molecular orbital crystallization in the d${}^1$ thiospinel ZnTi${}_2$S${}_4$ prepared via a reductive ion-exchange reaction