Theory of Sodium Ordering in NaxCoO2

Abstract

The ordering of Na ions in Na${}_x$CoO${}_2$ is investigated systematically by combining detailed density functional theory (DFT) studies with model calculations. Various ground state ordering patterns are identified, and they are in excellent agreement with avaliable experimental results. Our results suggest that the primary driving force for the Na ordering is the screened Coulomb interaction among Na ions. Possible effects of the Na ordering on the electronic structure of the CoO${}_2$ layer are discussed. We propose that the nonexistence of a charge ordered insulating state at $x=2/3$ is due to the lack of a commensurate Na ordering pattern, whereas an extremely stable Na ordering at $x=0.5$ enhances the charge ordering tendency, resulting in an insulating state as observed experimentally.

arXiv commentPhysical Review B, in press

References in corpus (10)

• The SIESTA method for ab initio order-N materials simulation
• Efficient index handling of multidimensional periodic boundary conditions
• Selfconsistent order-N density-functional calculations for very large systems
• Charge-ordering, commensurability and metallicity in the phase diagram of layered Na(x)CoO(2)
• Coupling between electronic and structural degrees of freedom in the triangular lattice conductor NaxCoO2
• Charge Disproportionation and Spin Ordering Tendencies in Na(x)CoO2
• Possible effects of charge frustration in Na${}_x$CoO${}_2$: bandwidth suppression, charge orders and resurrected RVB superconductivity
• Doping effects on the electronic and structural properties of CoO2: An LSDA+U study
• Structural transition in NaxCoO2 with x near 0.75 due to Na rearrangement
• Electron correlation in the two-dimensional triangle lattice of Na${}_x$CoO${}_2$

Cited by in corpus (37)

• Patterning of sodium ions and the control of electrons in sodium cobaltate
• Ferromagnetism, paramagnetism and a Curie-Weiss metal in an electron doped Hubbard model on a triangular lattice
• Searching for Stable Na-ordered Phases in Single Crystal Samples of gamma-NaxCoO2
• Sodium vacancy ordering and the co-existence of localized spins and itinerant charges in NaxCoO2
• Electronic texture of the thermoelectric oxide Na0.75CoO2
• Spin correlations and cobalt charge states: A new phase diagram of sodium cobaltates
• NQR and X-ray investigation of the structure of Na${}_{2/3}$CoO${}_2$ compound
• Na ordering imprints a metallic kagome lattice onto the Co planes of Na2/3CoO2
• Direct link between low temperature magnetism and high temperature sodium order in NaxCoO2
• Raman Spectroscopy Study of alpha-, beta-, gamma-NaxCoO2 and gamma-(Ca,Sr)xCoO2
• Destruction of the small Fermi surfaces in Na${}_x$CoO${}_2$ by Na disorder
• Melting of the Na layers in solid Na0.8CoO2
• X-ray absorption spectroscopy on layered cobaltates Na_xCoO_2
• ^{59}Co NMR evidence for charge ordering below T_{CO}\sim 51 K in Na_{0.5}CoO_2
• Squaring the Triangle: Insulating Ground State of $N{a}_{0.5}Co{O}_2$
• Charge and Spin Ordering in Insulating Na${}_{0.5}$CoO${}_2$: Effects of Correlation and Symmetry
• Structural properties and cation ordering in layered hexagonal CaxCoO2
• Stripe correlations in Na${}_{0.75}$CoO${}_2$
• Sodium Trimer Ordering on NaxCoO2 Surface
• Restoration of long range order of Na ions in $N{a}_{x}Co{O}_2$ at high temperatures by sodium site doping
• Interplay between Magnetism and Na concentration in $N{a}_{x}Co{O}_2$
• Oxygen non-stoichiometry and the origin of Na ion ordering in P2-NaxCoO2
• Na-ion dynamics in Quasi-1D compound NaV2O4
• Interplay of frustration, magnetism, charge ordering, and covalency in a model of Na0.5CoO2
• Magnetic Phase Transition at 88 K in Na0.5CoO2 revealed by 23Na-NMR investigations
• Dopant incorporation site in sodium cobaltate's host lattice: A critical factor for thermoelectric performance
• Ionic Hubbard model on a triangular lattice for Na_0.5CoO_2, Rb_0.5CoO_2 and K_0.5CoO_2: Mean-field slave boson theory
• Pressure effects in the triangular layered cobaltites NaxCoO2
• Magnetic, electrochemical and thermoelectric properties of $P2-N{a}_x(C{o}_{7/8}S{b}_{1/8})O_2$
• Electronic and magnetic properties of the ionic Hubbard model on the striped triangular lattice at 3/4 filling
• Interplay between mesoscopic phase separation and bulk magnetism in the layered NaxCoO2
• Superconductivity, charge ordering and structural properties of alpha and beta-NaxCoO2.y(H2O, D2O)
• Na Site Doping a Pathway for Enhanced Thermoelectric Performance in $N{a}_{1-x}Co{O}_2$; The Case of Gd and Yb Dopants
• Angular-dependent Magnetoresistance Oscillations in Na${}_{0.48}$CoO${}_2$ Single Crystal
• Transition from a phase-segregated state to single-phase incommensurate sodium ordering in Na_xCoO_2 with x \approx 0.53
• Sodium ion ordering of Na0.77CoO2 under competing multi-vacancy cluster, superlattice and domain formation
• Temperature-driven sodium-ion dynamical-to-static crossover in the zig-zag ordered phase of Na${}_{0.5}$CoO${}_2$