Charge dynamics in metallic CuO2 layers

A short overview with quantitative comparisons, including several recent results, is given on the charge dynamics in metallic cuprates. The in-plane charge response, studied by dc transport and optical techniques, varies systematically with carrier concentration. Near the concentration for optimal superconductivity, ρab(T) and the scattering rate Γ*(ω) increase nearly linearly over wide temperature and frequency ranges, respectively. The corresponding slopes dρab/dT and dΓ*/dω are essentially the same for the different compound families even when the optimized Tc's are very different. The close connection between resistivity and scattering rate is also found to hold in the ''overdoped'' range, where the super-linear increase of ρab(T) and Γ*(ω) has been studied in detail recently. A novel power-law dependence ρab∝T1.5±0.1 was observed from 4 K to ∝1000 K in overdoped La1.66Sr0.34CuO4. (orig.)