Incoherent charge dynamics of La2-xSrxCuO4:: Dynamical localization and resistivity saturation -: art. no. 134501

We performed the systematic optical and transport experiment for La2-xSrxCuO4 at high temperatures. The in-plane resistivity rho(ab)(T) saturates not at the classical Ioffe-Regel-Mott limit but at much higher value. The in-plane optical conductivity sigma(ab)(omega) exhibits at high temperatures a less characteristic, nearly flat spectrum over a wide energy range up to 1 eV without a Drude peak, irrespective of the positive slope of rho(ab). For small omega, sigma(ab)(omega) even possesses a broad finite-energy peak at high temperatures, suggesting dynamical localization. These characteristics are explained in terms of the breakdown of the quasiparticle picture due to strong scattering.