Elliptical hole pockets in the Fermi surfaces of unhydrated and hydrated sodium cobalt oxides

Abstract

The surprise discovery of superconductivity below 5K in sodium cobalt oxides when hydrated with water has caught the attention of experimentalists and theorists alike. Most explanations for its occurence have focused heavily on the properties of some small elliptically shaped pockets predicted to be the electronically dominant Fermi surface sheet, but direct attempts to look for them have instead cast serious doubts over their existence. Here we present evidence that these pockets do indeed exist, based on bulk measurements of the electron momentum distribution in unhydrated and hydrated sodium cobalt oxides using the technique of x-ray Compton scattering.

References in corpus (32)

• Spin entropy as the likely source of enhanced thermopower in $\rm\bf Na_xCo_2O_4
• An Electronic Model for $Co{O}_2$ layer based systems: Chiral RVB metal and Superconductivity
• Fermi surface and quasiparticle dynamics of Na(x)CoO2 {x=0.7} investigated by Angle-Resolved Photoemission Spectroscopy
• Coupling between electronic and structural degrees of freedom in the triangular lattice conductor NaxCoO2
• Superconductivity in CoO${}_2$ Layers and the Resonating Valence Bond Mean Field Theory of the Triangular Lattice t-J model
• Doped t-J Model on a Triangular Lattice: Possible Application to Na${}_x$CoO${}_2\cdot y$H${}_2$0 and Na${}_{1-x}$TiO${}_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
• Superconducting states in frustrating t-J model: A model connecting high-$T_c$ cuprates, organic conductors and Na${}_x$CoO${}_2$
• Thermodynamic and Transport Measurements on Superconducting Na_xCoO_2 + yH_2O Single Crystals Prepared by Electrochemical De-intercalation
• Crystal Structure and Elementary Properties of NaxCoO2 (x = 0.32, 0.5, 0.6, 0.75, and 0.92) in the Three-Layer NaCoO2 Family
• Ferromagnetic fluctuation and possible triplet superconductivity in Na_xCoO_2*yH_2O: Fluctuation-exchange study of multi-orbital Hubbard model
• Possible spin triplet superconductivity in Na${}_x$CoO${}_2\cdot y$H${}_2$0
• Electron correlation and Fermi surface topology of Na${}_x$CoO${}_2$
• Possible spin-triplet $f$-wave pairing due to disconnected Fermi surfaces in Na${}_x$CoO${}_2\cdot y$H${}_2$O
• Nesting, spin-fluctuations, and odd-gap superconductivity in NaxCoO2 yH2O
• Low-lying quasiparticle states and hidden collective charge instabilities in parent cobaltate superconductors (NaxCoO2)
• A critical assessment of the pairing symmetry in NaxCoO2.yH2O
• The Fermi surface of Na${}_x$CoO${}_2$
• Effect of Dynamical Coulomb Correlations on the Fermi Surface of Na_0.3CoO_2
• Quasiparticle coherence and the nature of the metal-insulator phase transition in Na${}_x$CoO${}_2$
• Angle-resolved photoemission study of cobalt oxide superconductor NaxCoO2.yH2O : Observation of the Fermi surface
• Magnetic susceptibility study of hydrated and non-hydrated NaxCoO2-yH2O single crystals
• Observation of a strongly nested Fermi surface in the shape-memory alloy Ni[0.62]Al[0.38]
• Destruction of the small Fermi surfaces in Na${}_x$CoO${}_2$ by Na disorder
• Investigation of the Spin Density Wave in NaxCoO2
• Ferromagnetic and triplet-pairing instabilities controlled by the trigonal distortion of the CoO_6 octahedra in Na_xCoO_2*yH_2O
• Shubnikov de Haas effect in the metallic state of Na${}_{0.3}$CoO${}_2$
• Deformation of Electronic Structures Due to CoO6 Distortion and Phase Diagrams of NaxCoO2.yH2O
• Na${}_x$CoO${}_2$ in the x -> 0 Regime: Coupling of Structure and Correlation effects
• Electronic structure and Fermi surface tolopogy of Na${}_x$CoO${}_2$
• Influence of water intercalation on the electronic structure of the hydrated Na0.3CoO2.yH2O using a local spin density approximation

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• Can disorder alone destroy the eg' hole pockets of NaxCoO2? A Wannier function based first-principles method for disordered systems
• Competing orders in Na${}_x$CoO${}_2$ from strong correlations on a two-particle level
• The low-energy ARPES and heat capacity of Na${}_{0.3}$CoO${}_2$: A DMFT study
• Calculating electron momentum densities and Compton profiles using the linear tetrahedron method
• Fermiology via the electron momentum distribution
• Electronic Quantum Confinement in Cylindrical Potential Well
• The Valence Transition Model of Pseudogap, Charge-Order and Superconductivity in Electron- and Hole-Doped Copper Oxides
• Coulomb correlations do not fill the e'_g hole pockets in Na_{0.3}CoO_2
• The electronic structure of the Na${}_x$CoO${}_2$ surface
• Spin fluctuations, magnetic long-range order and Fermi surface gapping in NaxCoO2
• Considerable non-local electronic correlations in strongly doped Na${}_x$CoO${}_2$
• Hall effect on the triangular lattice
• Theory of carrier concentration-dependent electronic behavior in layered cobaltates
• Ab-initio studying of spin states of sodium cobaltate Na${}_{2/3}$CoO${}_2$
• Similarities in electronic properties of organic charge-transfer solids and layered cobaltates