Conclusion

Abstract

In this study, the charge dynamics of the high temperature cuprate superconductor YBa$_2$(Cu$_{1-x}$Zn$_x$)$_3$O$_y$ over the electronic phase diagram have been investigated in a very wide doping range, as well as, for several Zn-contents, both in the normal and the superconducting state. The temperature dependent reflectivity measurements have been performed with Fourier transform infrared spectroscopy over a wide energy range. The optical conductivity spectra have been calculated from the reflectivity by using the Kramers-Krönig transformation. Detailed spectral weight analysis is performed on the optical conductivity spectra, especially in the pseudogap region. Several issues regarding to the electronic phase diagram were discussed. As a result, we obtained several important conclusions. Firstly, the behavior of the pseudogap in the superconducting state, secondly, the behavior of a precursor of superconductivity, and finally, some remarks related to the kinetic energy driven superconductivity were summarized below.