Enhanced superconductivity by Na doping in (Cu0.5Tl0.25Na0.25)Ba2Ca2Cu3O10-δ

We have studied for the first time, the reproducible method of doping the CuO2 planes in (Cu0.5Tl0.5)Ba2Ca2Cu3O10-δ superconductor with the intercalation of Na at Cu0.5Tl0.5Ba2O4-δ charge reservoir layer. The zero resistivity critical temperature Tc (R = 0) and magnitude of diamagnetism are increased with Na doping. However, Na containing sample doped with Mg and Be, the Tc (R = 0) and quantity of diamagnetism are suppressed. When these results are coupled with X-ray diffraction studies, it is seen that the decrease c-axes length with Mg and Be enhances the inter-plane coupling to such an extent that repulsion starts among the carriers, which possibly suppress the superconductivity parameters. The self-doping of Na-doped samples have shown enhanced superconductivity parameters, which is most likely accomplished through the optimization of carriers in the conducting CuO2 planes.