Non-Fermi Liquid Behavior in Nearly Charge Ordered Layered Metals

Abstract

Non-Fermi liquid behavior is shown to occur in two-dimensional metals which are close to a charge ordering transition driven by the Coulomb repulsion. A linear temperature dependence of the scattering rate together with an increase of the electron effective mass occur above $T^{*}$, a temperature scale much smaller than the Fermi temperature. It is shown that the anomalous temperature dependence of the optical conductivity of the quasi-two-dimensional organic metal $\alpha \mathrm{\text{−}}(\mathrm{BEDT}\mathrm{\text{−}}\mathrm{TTF}{)}_{2}M\mathrm{Hg}(\mathrm{SCN}{)}_4$, with $M={\mathrm{NH}}_4$ and Rb, above $T^{*}=50–100\mathrm{K}$, agrees qualitatively with predictions for the electronic properties of nearly charge ordered two-dimensional metals.