Charge and spin order on the triangular lattice -- Na${}_x$CoO${}_2$ at $x=0.5$

Abstract

The nature of electronic states due to strong correlation and geometric frustration on the triangular lattice is investigated in connection to the unconventional insulating state of Na${}_x$CoO${}_2$ at $x=0.5$. We study an extended Hubbard model using a spatially unrestricted Gutzwiller approximation. We find a new class of charge and spin ordered states at $x=1/3$ and $x=0.5$ where antiferromagnetic (AF) frustration is alleviated via weak charge inhomogeneity. At $x=0.5$, we show that the $\sqrt{3}a\times 2a$ off-plane Na dopant order induces weak $\sqrt{3}a\times 1a$ charge order in the Co layer. The symmetry breaking enables successive $\sqrt{3}a\times 1a$ AF and $2a\times 2a$ charge/spin ordering transitions at low temperatures. The Fermi surface is truncated by the $2a\times 2a$ hexagonal zone boundary into small electron and hole pockets. We study the phase structure and compare to recent experiments.

arXiv comment4 pages, 4 figures, revtex4 file

References in corpus (21)

• Charge-ordering, commensurability and metallicity in the phase diagram of layered Na(x)CoO(2)
• Fermi surface and quasiparticle dynamics of Na(x)CoO2 {x=0.7} investigated by Angle-Resolved Photoemission Spectroscopy
• Low temperature phase transitions and crystal structure of Na0.5CoO2
• Magnetic ordering and spin waves in $\mathbf{N}{\mathbf{a}}_{0.82}\mathbf{Co}{\mathbf{O}}_2$
• Fermi surface evolution and Luttinger theorem in Na${}_x$CoO${}_2$: a systematic photoemission study
• ARPES on Na${}_{0.6}$CoO${}_2$: Fermi surface, extended flat dispersion, and unusual band splitting
• Possible effects of charge frustration in Na${}_x$CoO${}_2$: bandwidth suppression, charge orders and resurrected RVB superconductivity
• Magnetic Correlation of NaxCoO2 and Successive Phase Transitions of Na0.5CoO2 -NMR and Neutron Diffraction Studies-
• Electron correlation and Fermi surface topology of Na${}_x$CoO${}_2$
• Neutron scattering study of novel magnetic order in Na0.5CoO2
• Novel Charge Order and Superconductivity in Two-Dimensional Frustrated Lattice at Quarter Filling
• NMR study of the magnetic and metal-insulator transitions in Na0.5CoO2: a nesting scenario
• Quasiparticle coherence and the nature of the metal-insulator phase transition in Na${}_x$CoO${}_2$
• Infrared spectroscopy of the charge ordering transition in Na${}_{0.5}$CoO${}_2$
• Disproportionation Transition at Critical Interaction Strength: Na${}_{1/2}$CoO${}_2$
• The infrared conductivity of Na${}_x$CoO${}_2$: evidence of gapped states
• Charge order and superconductivity in a two-dimensional triangular lattice at n=2/3
• Unrestricted renormalized mean field theory of strongly correlated electron systems
• Destruction of the small Fermi surfaces in Na${}_x$CoO${}_2$ by Na disorder
• Shubnikov de Haas effect in the metallic state of Na${}_{0.3}$CoO${}_2$
• Inhomogeneous states with checkerboard order in the t-J Model

Cited by in corpus (21)

• Searching for Stable Na-ordered Phases in Single Crystal Samples of gamma-NaxCoO2
• Spin correlations and cobalt charge states: A new phase diagram of sodium cobaltates
• Nodal $d+id$ pairing and topological phases on the triangular lattice: unconventional superconducting state of Na${}_x$CoO${}_2\cdot y$H${}_2$O
• Triangular Spin-Orbit-Coupled Lattice with Strong Coulomb Correlations: Sn Atoms on a SiC(0001) Substrate
• Phase diagram of the triangular extended Hubbard model
• Competing orders in Na${}_x$CoO${}_2$ from strong correlations on a two-particle level
• Nonlinear current-voltage behavior and electrically driven phase transition in charge frustrated LuFe2O4
• ^{59}Co NMR evidence for charge ordering below T_{CO}\sim 51 K in Na_{0.5}CoO_2
• Extended Gutzwiller Approximation for Inhomogeneous System
• Itinerant and localized magnetism on the triangular lattice: sodium rich phases of Na${}_x$CoO${}_2$
• Rearrangement of Sodium ordering and its effect on physical properties in $N{a}_{x}Co{O}_2$ system
• Textured electronic states of the triangular lattice Hubbard model and Na${}_x$CoO${}_2$
• Interplay of frustration, magnetism, charge ordering, and covalency in a model of Na0.5CoO2
• Charge-Order on the Triangular Lattice: A Mean-Field Study for the Lattice $S=1/2$ Fermionic Gas
• Emergent charge ordering in near half doped Na${}_{0.46}$CoO${}_2$
• 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
• Interplay of magnetism and superconductivity in 2D extended Hubbard model
• NMR studies of Successive Phase Transitions in Na0.5CoO2 and K0.5CoO2
• Magnetic correlations in subsystems of the misfit [Ca${}_2$CoO${}_3$]${}_{0.62}$[CoO${}_2$] cobaltate
• Thermal fluctuations in superconducting phases with chiral $d+id$ and $s$ symmetry on a triangular lattice
• Temperature-driven sodium-ion dynamical-to-static crossover in the zig-zag ordered phase of Na${}_{0.5}$CoO${}_2$