2-D and mott transition studies on metal (M) doped PrBa₂Cu ₃O₇

We doped PrBa₂Cu₃O₇ (PBCO) using various metals (M) to obtain PrBa₂[Cu_(1-x)M _x ]O ₇ (PBCMO) ceramic samples and epitaxial thin films. As suggested in the above chemical composition, these samples were made by replacing some of the Cu ions in PBCO with its metallic neighbors (M) such as Al, Co, Fe, Ga, Ni, and Zn at four different doping concentrations (x)-0.05, 0.10, 0.15, and 0.20. The epitaxial films were made by performing laser ablation on a ceramic disk target. We also present the results of our transport and Raman studies on the aforementioned PBCMO samples. From our Raman data, we were able to identify the doping sites used. Combined with the transport data, this enabled us to explain the abnormal increase in the electrical resistivity of our doped samples. Our transport property studies on PBCMO samples and the YBCO/PBCMO multilayer allowed us to deduce the superconducting coupling length, the finite-size effect, and the two-dimensional phase transition of YBCO.