Finite temperature properties of the triangular lattice t-J model, applications to Na${}_x$CoO${}_2$

Abstract

We present a finite temperature ($T$) study of the t-J model on the two-dimensional triangular lattice for the negative hopping $t$, as relevant for the electron-doped Na${}_x$CoO${}_2$ (NCO). To understand several aspects of this system, we study the $T$-dependent chemical potential, specific heat, magnetic susceptibility, and the dynamic Hall-coefficient across the entire doping range. We show systematically, how this simplest model for strongly correlated electrons describes a crossover as function of doping ($x$) from a Pauli-like weakly spin-correlated metal close to the band-limit (density $n=2$) to the Curie-Weiss metallic phase ($1.5<n<1.75$) with pronounced anti-ferromagnetic (AFM) correlations at low temperatures and Curie-Weiss type behavior in the high-temperature regime. Upon further reduction of the doping, a new energy scale, dominated by spin-interactions ($J$) emerges (apparent both in specific heat and susceptibility) and we identify an effective interaction $J_{eff}(x)$, valid across the entire doping range. This is distinct from Anderson's formula, as we choose here $t<0$, hence the opposite sign of the usual Nagaoka-ferromagnetic situation. This expression includes the subtle effect of weak kinetic AFM - as encountered in the infinitely correlated situation ($U=\infty$). By explicit computation of the Kubo-formulae, we address the question of practical relevance of the high-frequency expression for the Hall coefficient $R_H^{\ast }$. We hope to clarify some open questions concerning the applicability of the t-J model to real experimental situations through this study.

References in corpus (20)

• Spin entropy as the likely source of enhanced thermopower in $\rm\bf Na_xCo_2O_4
• Charge-ordering, commensurability and metallicity in the phase diagram of layered Na(x)CoO(2)
• The Physics Behind High-Temperature Superconducting Cuprates: The "Plain Vanilla" Version Of RVB
• Exact spectra, spin susceptibilities and order parameter of the quantum Heisenberg antiferromagnet on the triangular lattice
• Fermi surface and quasiparticle dynamics of Na(x)CoO2 {x=0.7} investigated by Angle-Resolved Photoemission Spectroscopy
• Unconventional magnetic transition and transport behavior in Na0.75CoO2
• Superconductivity in CoO${}_2$ Layers and the Resonating Valence Bond Mean Field Theory of the Triangular Lattice t-J model
• Specific-heat evidence for strong electron correlations in the thermoelectric material (Na,Ca)Co_{2}O_{4}
• 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
• Possible effects of charge frustration in Na${}_x$CoO${}_2$: bandwidth suppression, charge orders and resurrected RVB superconductivity
• Unconventional Charge Ordering in Na0.70CoO2 below 300 K
• Kinetic Antiferromagnetism in the Triangular Lattice
• Thermodynamic properties of the planar $t-J$ model
• Electron correlation in the two-dimensional triangle lattice of Na${}_x$CoO${}_2$
• The Full Mottness
• Spectral measurement of the Hall angle response in normal state cuprate superconductors
• Reactive Hall response
• Memory function approach to the Hall constant in strongly correlated electron systems
• Reactive Hall constant of Strongly Correlated Electrons
• Temperature Dependence of Hall Response in Doped Antiferromagnets

Cited by in corpus (10)

• Electro Thermal Transport Coefficients at Finite Frequencies
• The Kelvin Formula for Thermopower
• Classical Antiferromagnetism in Kinetically Frustrated Electronic Models
• Interplay between magnetic properties and thermoelectricity in misfit and Na cobaltates
• Transport properties of the layered Rh oxide K_0.49RhO_2
• Thermoelectric effects in a strongly correlated model for Na${}_x$CoO${}_2$
• Magnetization processes and existence of reentrant phase transitions in coupled spin-electron model on doubly decorated planar lattices
• Hall effect on the triangular lattice
• Electronic and magnetic properties of the ionic Hubbard model on the striped triangular lattice at 3/4 filling
• Exploring Frustration Effects of Strongly Interacting Bosons via the Hall Response