Interplay of frustration, magnetism, charge ordering, and covalency in a model of Na0.5CoO2

Abstract

We investigate an effective Hamiltonian for Na0.5CoO2 that includes the electrostatic potential due to the ordered Na ions and strong electronic correlations. This model displays a subtle interplay between metallic and insulating phases and between charge and magnetic order. For realistic parameters, the model predicts an insulating phase with similarities to a covalent insulator. We show that this interpretation gives a consistent explanation of experiments on Na0.5CoO2, including the small degree of charge ordering, the small charge gap, the large moment, and the optical conductivity.

5 pages, 4 figures. Text revised making more emphasis on model properties. Figures compacted

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Cited by in corpus (8)

• Quantum frustration in organic Mott insulators: from spin liquids to unconventional superconductors
• The Paired Electron Crystal: order from frustration in the quarter-filled band
• Extended Hubbard model: Charge Ordering and Wigner-Mott transition
• Topological spin liquid phase in a low-dimensional organic molecular compound
• 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
• Electronic and magnetic properties of the ionic Hubbard model on the striped triangular lattice at 3/4 filling
• Generalization of Lieb-Wu wave function inspired by one-dimensional ionic Hubbard model