| Popis: |
Infrared and optical spectroscopy have been applied to study the normal state prop- erties of the La2-xSrxCuO4 cuprate superconductor. The c-plane optical response of single crystals of La2-xSrxCuO4 was studied from underdoped to overdoped regions at 32, 80, and 300 K. The doping dependent reflectance spectra were measured from far infrared (10 cm-1) to ultraviolet (50,000 cm-1). The spectra were modeled us- ing the Drude-Lorentz model, which replicates the experimental data of the samples and provides an understanding of the physical phenomena happening in the infrared, visible and ultraviolet regions of radiation. The doping dependence of phonon pa- rameters, i.e., transverse frequency ¿0, plasma frequency ¿p, and scattering rate ¿ are discussed for all observed modes in the La2-xSrxCuO4 reflectance curves. Our results indicate that the temperature and doping level have strong and important effects on the lattice vibrations, especially at room temperature. Another interesting result is a signal of the conducting state observed at a higher doping level, indicating an induction of metallic behavior. |
