Spin fluctuations, magnetic long-range order and Fermi surface gapping in NaxCoO2

Abstract

In this study an extended low energy phase diagram for NaxCoO2 is experimentally established with emphasis on the high x range. It is based on systematic heat capacity studies on both polycrystalline and single crystalline samples and on uSR measurements. Main features are the existence of mass enhancement, spin fluctuations without long-range order, and magnetic order with associated Fermi surface gapping. The latter is seen in the electronic density of states (DOS) and suppression of nuclear specific heat. While there is agreement between the band structure and the low energy DOS in the low x range, in the high x range (x > 0.6) the thermodynamically determined DOS is approximately three times that deduced from the angle-resolved photoemission spectroscopy (ARPES)-measured band dispersion or local-density approximation (LDA) calculations.

9 pages, 5 figures

References in corpus (32)

• Charge-ordering, commensurability and metallicity in the phase diagram of layered Na(x)CoO(2)
• Large enhancement of the thermopower in Na${}_x$CoO${}_2$ at high Na doping
• Patterning of sodium ions and the control of electrons in sodium cobaltate
• Fermi surface and quasiparticle dynamics of Na(x)CoO2 {x=0.7} investigated by Angle-Resolved Photoemission Spectroscopy
• Unconventional magnetic transition and transport behavior in Na0.75CoO2
• Coupling between electronic and structural degrees of freedom in the triangular lattice conductor NaxCoO2
• Magnetic ordering and spin waves in $\mathbf{N}{\mathbf{a}}_{0.82}\mathbf{Co}{\mathbf{O}}_2$
• ARPES on Na${}_{0.6}$CoO${}_2$: Fermi surface, extended flat dispersion, and unusual band splitting
• Charge Disproportionation and Spin Ordering Tendencies in Na(x)CoO2
• Bulk antiferromagnetism in $\mathbf{N}{\mathbf{a}}_{0.82}\mathbf{Co}{\mathbf{O}}_2$ single crystals
• Ferromagnetic in-plane spin fluctuations in NaxCoO2 observed by neutron inelastic scattering
• Structure and Dynamics of Superconducting NaxCoO(2) Hydrate and Its Unhydrated Analog
• Static magnetic order in Na${}_{0.75}$CoO${}_2$ detected by muon spin rotation and relaxation
• 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${}_2$
• Low-lying quasiparticle states and hidden collective charge instabilities in parent cobaltate superconductors (NaxCoO2)
• Complete d-Band Dispersion and the Mobile Fermion Scale in NaxCoO2
• Effect of Dynamical Coulomb Correlations on the Fermi Surface of Na_0.3CoO_2
• Structural transition in NaxCoO2 with x near 0.75 due to Na rearrangement
• Non-magnetic insulator state in Na1CoO2 and phase separation of Na vacancies
• Direct link between low temperature magnetism and high temperature sodium order in NaxCoO2
• Anisotropic quasiparticle renormalization in Na0.73CoO2: role of inter-orbital interactions and magnetic correlations
• Elliptical hole pockets in the Fermi surfaces of unhydrated and hydrated sodium cobalt oxides
• Investigation of the Spin Density Wave in NaxCoO2
• Precise Control of Band Filling in NaxCoO2
• A Tight-Binding Investigation of the NaxCoO2 Fermi Surface
• Synthesis, Characterization, and Magnetic Properties of gamma-NaxCoO2 (0.70 < x <0.84)
• Spin gaps and magnetic structure of NaxCoO2
• Magnetic Fluctuations in the Metallic State of Na${}_{0.7}$CoO${}_2$ Revealed by ${}^{23}$Na NMR
• Thermal and Electrical Properties of gamma-NaxCoO2 (0.70 < x < 0.78)
• NaxCoO2: Enhanced low-energy excitations of electrons on a 2D triangular lattice
• Electronic theory for itinerant in-plane magnetic fluctuations in Na${}_x$CoO${}_2$

Cited by in corpus (9)

• Experimental study of the incoherent spectral weight in the photoemission spectra of the misfit cobaltate [Bi2Ba2O4][CoO2]2
• Strong correlations enhanced by charge-ordering in highly doped cobaltates
• Magnetic field dependent specific heat and enhanced Wilson ratio in strongly correlated layered cobalt oxide
• Considerable non-local electronic correlations in strongly doped Na${}_x$CoO${}_2$
• New electronic orderings observed in cobaltates under the influence of misfit periodicities
• ω/T scaling of the optical conductivity in strongly correlated layered cobalt oxide
• Ab-initio studying of spin states of sodium cobaltate Na${}_{2/3}$CoO${}_2$
• Statistical fluxes and the Curie-Weiss metal state
• Thermopower enhancement from engineering the Na${}_{0.7}$CoO${}_2$ interacting fermiology via Fe doping