Enhanced superconductivity by Na doping in (Cu 0.5Tl 0.25Na 0.25)Ba 2Ca 2Cu 3O 10− δ

Abstract

We have studied for the first time, the reproducible method of doping the CuO 2 planes in (Cu 0.5Tl 0.5)Ba 2Ca 2Cu 3O 10− δ superconductor with the intercalation of Na at Cu 0.5Tl 0.5Ba 2O 4− δ charge reservoir layer. The zero resistivity critical temperature T c ( R = 0) and magnitude of diamagnetism are increased with Na doping. However, Na containing sample doped with Mg and Be, the T c ( 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 CuO 2 planes.