Local moment, itinerancy and deviation from Fermi liquid behavior in Na${}_x$CoO${}_2$ for $0.71\le x\le 0.84$

Abstract

Here we report the observation of Fermi surface (FS) pockets via the Shubnikov de Haas effect in Na${}_x$CoO${}_2$ for $x=0.71$ and 0.84, respectively. Our observations indicate that the FS expected for each compound intersects their corresponding Brillouin zones, as defined by the previously reported superlattice structures, leading to small reconstructed FS pockets, but only if a precise number of holes per unit cell is \emph{localized}. For $0.71\le x<0.75$ the coexistence of itinerant carriers and localized $S=1/2$ spins on a paramagnetic triangular superlattice leads at low temperatures to the observation of a deviation from standard Fermi-liquid behavior in the electrical transport and heat capacity properties, suggesting the formation of some kind of quantum spin-liquid ground state.

4 pages, 4 figures

References in corpus (5)

• Fermi surface and quasiparticle dynamics of Na(x)CoO2 {x=0.7} investigated by Angle-Resolved Photoemission Spectroscopy
• Fermi surface evolution and Luttinger theorem in Na${}_x$CoO${}_2$: a systematic photoemission study
• Three-Dimensional Spin Fluctuations in Na0.75CoO2
• Complete d-Band Dispersion and the Mobile Fermion Scale in NaxCoO2
• Searching for Stable Na-ordered Phases in Single Crystal Samples of gamma-NaxCoO2

Cited by in corpus (6)

• Anisotropy in the electrical resistivity and susceptibility of superconducting BaFe${}_2$As${}_2$ single crystals
• Sodium vacancy ordering and the co-existence of localized spins and itinerant charges in NaxCoO2
• Spin correlations and cobalt charge states: A new phase diagram of sodium cobaltates
• Na ordering imprints a metallic kagome lattice onto the Co planes of Na2/3CoO2
• Correlation effects on the doped triangular lattice in view of the physics of sodium-rich Na${}_x$CoO${}_2$
• Rearrangement of Sodium ordering and its effect on physical properties in $N{a}_{x}Co{O}_2$ system