Thermoelectric effects in a strongly correlated model for Na${}_x$CoO${}_2$

Abstract

Thermal response functions of strongly correlated electron systems are of appreciable interest to the larger scientific community both theoretically and technologically. Here we focus on the infinitely correlated t-J model on a geometrically frustrated two-dimensional triangular lattice. Using exact diagonalization on a finite sized system we calculate the dynamical thermal response functions in order to determine the thermopower, Lorenz number, and dimensionless figure of merit. The dynamical thermal response functions is compared to the infinite frequency limit and shown to be very weak functions of frequency, hence, establishing the validity of the high frequency formalism recently proposed by Shastry for the thermopower, Lorenz number, and the dimensionless figure of merit. Further, the thermopower is demonstrated to have a low to mid temperature enhancement when the sign of the hopping parameter $t$ is switched from positive to negative for the geometrically frustrated lattice considered.

arXiv comment16 pages, 10 figures, color version available at http://physics.ucsc.edu/~peterson/mrpeterson-condmat-NCO.pdf. V.2 has fixed minor typos in Eq. 11, 19, 25, and 26. V.3 is a color version

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• Getting back to Na_xCoO_2: spectral and thermoelectric properties
• Enhancement of the thermoelectric power by electronic correlations in bad metals: a study of the Kelvin formula
• Thermoelectric transport properties of an apparent Fermi liquid: Relation to an analytic anomaly in the density of states and application to hole-doped delafossites
• Statistical fluxes and the Curie-Weiss metal state
• Thermopower enhancement from engineering the Na${}_{0.7}$CoO${}_2$ interacting fermiology via Fe doping