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Giant electron-electron scattering in the Fermi-liquid state of Na_0.7CoO_2

S. Y. Li·Louis Taillefer·D. G. Hawthorn·M. A. Tanatar·Johnpierre Paglione·M. Sutherland·R. W. Hill·C. H. Wang·X. H. Chen
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Abstract

The in-plane resistivity, rho, and thermal conductivity, kappa, of a single crystal of Na_0.7CoO_2 were measured down to 40 mK. Verification of the Wiedemann-Franz law, kappa/T = L_0/rho as T -> 0, and observation of a T^2 dependence of rho at low temperature, rho = rho_0 + AT^2, establish the existence of a well-defined Fermi-liquid state. The measured value of coefficient A reveals enormous electron-electron scattering, characterized by the largest Kadowaki-Woods ratio, A/gamma^2, encountered in any material. The rapid suppression of A with magnetic field suggests a possible proximity to a magnetic quantum critical point. We also speculate on the possible role of magnetic frustration and proximity to a Mott insulator.

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S. Y. Li, Louis Taillefer, D. G. Hawthorn, M. A. Tanatar, Johnpierre Paglione, M. Sutherland, R. W. Hill, C. H. Wang, X. H. Chen. 2004-07-27. Giant electron-electron scattering in the Fermi-liquid state of Na_0.7CoO_2. https://doi.org/10.1103/physrevlett.93.056401

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