Na${}_x$CoO${}_2$ in the x -> 0 Regime: Coupling of Structure and Correlation effects

Abstract

The study of the strength of correlations in Na${}_x$CoO${}_2$ is extended to the x=0 end of the phase diagram where Mott insulating behavior has been widely anticipated. Inclusion of correlation as modeled by the LDA+U approach leads to a Mott transition in the $a_g$ subband if U is no less than U${}_c$=2.5 eV. Thus U smaller than U${}_c$ is required to model the metallic, nonmagnetic CoO${}_2$ compound reported by Tarascon and coworkers. The orbital-selective Mott transition of the $a_g$ state, which is essentially degenerate with the $e_g^{\prime }$ states, occurs because of the slightly wider bandwidth of the $a_g$ bands. The metal-insulator transition is found to be strongly coupled to the Co-O bond length, due to associated changes in the $t_{2g}$ bandwidth, but the largest effects occur only at a reduced oxygen height that lies below the equilibrium position.

arXiv comment8 pages with 9 embedded figures

References in corpus (30)

• Spin entropy as the likely source of enhanced thermopower in $\rm\bf Na_xCo_2O_4
• Charge-ordering, commensurability and metallicity in the phase diagram of layered Na(x)CoO(2)
• Superconductivity Phase Diagram of Na(x)CoO(2).1.3H(2)O
• Orbital-selective Mott transitions in the degenerate Hubbard model
• An Electronic Model for $Co{O}_2$ layer based systems: Chiral RVB metal and Superconductivity
• Unconventional Superconductivity and Electron Correlations in Cobalt Oxyhydrate Na${}_{0.35}$CoO${}_2$$\cdot y$H${}_2$O
• Superconductivity Near Ferromagnetism in MgCNi3
• Quantum Critical Behavior and Possible Triplet Superconductivity in Electron Doped CoO2 Sheets
• Charge Disproportionation and Spin Ordering Tendencies in Na(x)CoO2
• Thermodynamic and Transport Measurements on Superconducting Na_xCoO_2 + yH_2O Single Crystals Prepared by Electrochemical De-intercalation
• Observation of Bulk Superconductivity in NaxCoO2.yH2O and NaxCoO2.yD2O Powder and Single Crystals
• Ferromagnetic fluctuation and possible triplet superconductivity in Na_xCoO_2*yH_2O: Fluctuation-exchange study of multi-orbital Hubbard model
• Possible spin-triplet $f$-wave pairing due to disconnected Fermi surfaces in Na${}_x$CoO${}_2\cdot y$H${}_2$O
• Doping effects on the electronic and structural properties of CoO2: An LSDA+U study
• Nesting, spin-fluctuations, and odd-gap superconductivity in NaxCoO2 yH2O
• Superconductivity in Na_xCoO_2yH_2O by charge fluctuation
• The Role of hybridization in NaxCoO2 and the Effect of Hydration
• The Fermi surface of Na${}_x$CoO${}_2$
• Multi-orbital analysis on the Superconductivity in Na_{x}CoO_{2} \cdot y H_{2}O
• Revised superconducting phase diagram of hole doped Na${}_x$(H${}_3$O)${}_z$CoO${}_2\cdot y$H${}_2$O
• Effect of Dynamical Coulomb Correlations on the Fermi Surface of Na_0.3CoO_2
• Low energy electronic states and triplet pairing in layered cobaltates
• Infrared spectroscopy of the charge ordering transition in Na${}_{0.5}$CoO${}_2$
• Disproportionation Transition at Critical Interaction Strength: Na${}_{1/2}$CoO${}_2$
• Magnetism, Critical Fluctuations and Susceptibility Renormalization in Pd
• The infrared conductivity of Na${}_x$CoO${}_2$: evidence of gapped states
• Competition between singlet and triplet pairings in Na_xCoO_2 yH_2O
• Electronic States in Two-Dimensional Triangular Cobalt Oxides: Role of Electronic Correlation
• A Tight-Binding Investigation of the NaxCoO2 Fermi Surface
• Possible Pairing Symmetry of Superconductor Na_xCoO_2yH_2O

Cited by in corpus (9)

• The Paired Electron Crystal: order from frustration in the quarter-filled band
• Synthesis and properties of CoO2, the x = 0 end member of the LixCoO2 and NaxCoO2 systems
• Electronic Correlations in CoO2, the Parent Compound of Triangular Cobaltates
• From charge- and spin-ordering to superconductivity in the organic charge-transfer solids
• Elliptical hole pockets in the Fermi surfaces of unhydrated and hydrated sodium cobalt oxides
• Electrochemical synthesis and properties of CoO2, the x = 0 phase of the AxCoO2 systems (A = Li, Na)
• Theory of carrier concentration-dependent electronic behavior in layered cobaltates
• Comparison of the Electronic Structures of Two Non-cuprate Layered Transition Metal Oxide Superconductors
• Disproportionation and Critical Interaction Strength in Na${}_x$CoO${}_2$: Concentration Dependence