Suppression of Tc in Co-doped (Cu 0.5Tl 0.5)Ba 2Ca 2Cu 3− xCo xO 10− δ superconductor

Abstract

The most possible sources of suppression of superconducting properties (i.e., zero resistivity T c ( R = 0), magnitude of diamagnetism, etc.) in cobalt-doped (Cu 0.5Tl 0.5)Ba 2Ca 2Cu 3− x Co x O 10− δ ( x = 0, 0.05, 0.1, 0.5) superconductor have been explored. It has been observed from these studies that Co-doping at Cu 2+ sites in the CuO 2 planes somehow localizes the carriers at Co 3+ sites and decreases the density of mobile carriers in the superconducting CuO 2 planes. We doped Li at Tl sites in Cu 0.5Tl 0.5Ba 2O 4− δ charge reservoir to obtain an efficient carriers doping (Cu 0.5Tl 0.25Li 0.25)Ba 2O 4− δ charge reservoir layer of (Cu 0.5Tl 0.25Li 0.25)Ba 2Ca 2Cu 3− x Co x O 10− δ compound to replenish the density of mobile carriers in the CuO 2 planes; since alkali metals are known to lose their outermost “s-orbital” electron easily, which can be supplied to the superconducting CuO 2 planes. The increased free carrier density in the superconducting CuO 2 planes enhances the superconducting properties of the final compound.