Electron correlation and charge dynamics in high- Tc copper oxides — C-axis transport and optical properties

Abstract

Transport and optical properties perpendicular to the CuO 2 layers are extensively studies for La 2− x Sr x CuO 4. The electronic states are two-dimentional in the orthohombic phase where high- T c appears while in the tetragonal phase, at high T and large x, the anisotropy is reduced and the system is an anisotropic three-dimentional metal. The superconducting transition in the orthorhomsic phase restores the reduced anisotropy in the tetragonal phase.