Getting back to Na_xCoO_2: spectral and thermoelectric properties

Abstract

Sodium cobaltate Na_xCoO_2 as dopable strongly correlated layered material with a triangular sublattice still poses a challenging problem in condensed matter. The intriguing interplay between lattice, charge, spin and orbital degrees of freedom leads to a complex phase diagram bounded by a nominal Mott (x=0) regime and a band-insulating (x=1) phase. By means of the charge self-consistent density functional theory (DFT) plus dynamical mean-field theory (DMFT) scheme, built on a pseudopotential framework combined with a continuous-time quantum Monte-Carlo solver, we here study the one-particle spectral function A(k,ω) as well as the thermopower S(T). The computations may account for the suppression of the e_g' pockets in A(k,ω) at lower doping in line with photoemission experiments. Enhancement of the thermopower is verified within the present elaborate multi-orbital method to treat correlated materials. In addition, the two-particle dynamic spin susceptibility χ_s(ω,q) is investigated based on a simplified tight-binding approach, yet by including vertex contributions in the DMFT linear response. Besides the identification of paramagnon branches at higher doping, a prominent high-energy antiferromagnetic mode close to x=0.67 is therewith identified in χ_s(ω,q), which can be linked to extended hopping terms on the CoO_2 sublattice.

References in corpus (11)

• "Pudding mold" band drives large thermopower in Na${}_x$CoO${}_2$
• Plane-wave based electronic structure calculations for correlated materials using dynamical mean-field theory and projected local orbitals
• Fermi surface and quasiparticle dynamics of Na(x)CoO2 {x=0.7} investigated by Angle-Resolved Photoemission Spectroscopy
• Approaching finite-temperature phase diagrams of strongly correlated materials: a case study for V2O3
• Complete d-Band Dispersion and the Mobile Fermion Scale in NaxCoO2
• Spin correlations and cobalt charge states: A new phase diagram of sodium cobaltates
• Phase Diagram of Na${}_x$CoO${}_2$ Studied by Gutzwiller Density Functional Theory
• The low-energy ARPES and heat capacity of Na${}_{0.3}$CoO${}_2$: A DMFT study
• Hallmark of strong electronic correlations in LaNiO${}_3$: photoemission kink and broadening of fully occupied bands
• Thermoelectric effects in a strongly correlated model for Na${}_x$CoO${}_2$
• Enhancement of the effective disorder potential and the thermopower in Na${}_x$CoO${}_2$ through the electron-phonon coupling

Cited by in corpus (13)

• Thermopower and Entropy: lessons from Sr${}_2$RuO${}_4$
• Thermoelectricity in correlated narrow-gap semiconductors
• Collective Modes in Excitonic Magnets: Dynamical Mean-Field Study
• Efficient fluctuation exchange approach to low-temperature spin fluctuations and superconductivity: from the Hubbard model to Na${}_x$CoO${}_2\cdot y$H${}_2$O
• Interplay between Magnetism and Na concentration in $N{a}_{x}Co{O}_2$
• From Hubbard bands to spin-polaron excitations in the doped Mott material Na${}_x$CoO${}_2$
• Dopant incorporation site in sodium cobaltate's host lattice: A critical factor for thermoelectric performance
• LinReTraCe: The Linear Response Transport Centre
• Understanding the Seebeck coefficient of LaNiO3 compound in the temperature range 300-620 K
• Hidden covalent insulator and spin excitations in SrRu${}_2$O${}_6$
• Thermopower enhancement from engineering the Na${}_{0.7}$CoO${}_2$ interacting fermiology via Fe doping
• Quasiparticle approach to the transport in infinite-layer nickelates
• Time-resolved measurement of Seebeck effect for superionic metals during structural phase transition