Squaring the Triangle: Insulating Ground State of $N{a}_{0.5}Co{O}_2$

Abstract

We demonstrate that at a filling of $n=1.5$, an hexatic insulating state obtains in the extended Hubbard model on a triangular lattice. Composed of two tetragonal sublattices with fillings of $n=1$ and $n=2$, the insulating state is charge ordered and possesses an antiferromagnetic superlattice with dimension $a\times \sqrt{3}$. Two distinct energy scales arise in our model, a charge gap for the insulator and the effective exchange interaction in the antiferromagnet. Our model is capable of explaining both qualitatively and quantitatively the Hall coefficient including the sign change, the temperature dependence of the resistivity and the persistence of antiferromagnetism above the insulating state.

4.1 pages, 2 figures: The published version contains an explicit calculation of the dc resistivity as well as the Hall coefficient, both of which are compared with experiment

References in corpus (7)

• 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
• Theory of Sodium Ordering in NaxCoO2
• Neutron scattering study of novel magnetic order in Na0.5CoO2
• NMR study of the magnetic and metal-insulator transitions in Na0.5CoO2: a nesting scenario
• Spin-Dynamics in the Carrier-Doped $S=1/2$ Triangular-Lattice of Na${}_x$CoO${}_2$-yH${}_2$O
• Disproportionation Transition at Critical Interaction Strength: Na${}_{1/2}$CoO${}_2$

Cited by in corpus (16)

• The Paired Electron Crystal: order from frustration in the quarter-filled band
• Hall effect measurements on epitaxial SmNiO3 thin films and implications for antiferromagnetism
• ^{59}Co NMR evidence for charge ordering below T_{CO}\sim 51 K in Na_{0.5}CoO_2
• Temperature-driven transition from the Wigner Crystal to the Bond-Charge-Density Wave in the Quasi-One-Dimensional Quarter-Filled band
• Exotic Superconducting Phases of Ultracold Atom Mixtures on Triangular Lattices
• Formation of charge and spin ordering in strongly correlated electron systems
• Electronic phase diagram of LixCoO2 revisited with potentiostatically de-intercalated single crystals
• Rearrangement of Sodium ordering and its effect on physical properties in $N{a}_{x}Co{O}_2$ system
• Interplay of frustration, magnetism, charge ordering, and covalency in a model of Na0.5CoO2
• 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
• Theory of carrier concentration-dependent electronic behavior in layered cobaltates
• NMR studies of Successive Phase Transitions in Na0.5CoO2 and K0.5CoO2
• Similarities in electronic properties of organic charge-transfer solids and layered cobaltates
• On the Origin of the Metallic and Anisotropic Magnetic Properties of Na_xCoO_2 (x~~0.75)
• Temperature-driven sodium-ion dynamical-to-static crossover in the zig-zag ordered phase of Na${}_{0.5}$CoO${}_2$