Raman and Optical Reflection Studies of Electronic States in La2−xSrxCuO4

The electronic states in La2−xSrxCuO4 are systematically investigated by Raman scattering, infrared‐ultraviolet reflection spectroscopy, and electric resistivity. A narrow quasi‐particle band is created at EF and sharply grows up by collecting the density of states from the high energy region at 1–1.5 eV as temperature decreases near the insulator‐metal transition. The relaxation time of conducting carriers is limited by the quasi‐particle band width near the insulator‐metal transition, but it drastically increases in the overdoped phase. The quasi‐particle band gives the anomalous electronic properties.The electronic states in La2−xSrxCuO4 are systematically investigated by Raman scattering, infrared‐ultraviolet reflection spectroscopy, and electric resistivity. A narrow quasi‐particle band is created at EF and sharply grows up by collecting the density of states from the high energy region at 1–1.5 eV as temperature decreases near the insulator‐metal transition. The relaxation time of conducting carriers is limited by the quasi‐particle band width near the insulator‐metal transition, but it drastically increases in the overdoped phase. The quasi‐particle band gives the anomalous electronic properties.