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Strong Correlations Produce the Curie-Weiss Phase of Na$_{x}$CoO$_2$

Jan O. Haerter·Michael R. Peterson·B. Sriram Shastry
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Abstract

Within the t-J model we study several experimentally accessible properties of the 2D-triangular lattice system Na$_x$CoO$_2$, using a numerically exact canonical ensemble study of 12 to 18 site triangular toroidal clusters as well as the icosahedron. Focusing on the doping regime of $x\sim0.7$, we study the temperature dependent chemical potential, specific heat, magnetic susceptibility and the dynamic Hall coefficient $R_H(T,ω)$ as well as the magnetic field dependent thermopower. We find a crossover between two phases near $x \sim 0.75$ in susceptibility and field suppression of the thermopower arising from strong correlations. An interesting connection is found between the temperature dependence of the diamagnetic susceptibility and the Hall-coefficient. We predict a large thermopower enhancement, arising from {\em transport corrections} to the Heikes-Mott formula, in a model situation where the sign of hopping is reversed from that applicable to Na$_x$CoO$_2$.

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Jan O. Haerter, Michael R. Peterson, B. Sriram Shastry. 2006-10-14. Strong Correlations Produce the Curie-Weiss Phase of Na$_{x}$CoO$_2$. https://doi.org/10.1103/physrevlett.97.226402

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