Cu0.5Tl0.5Ba2Ca3Cu4−y Zn y O12−δ (y=0, 1.0, 2.0, 3.0, 3.5): Superconductor with Four ZnO2 Planes

Abstract

A new Cu0.5Tl0.5Ba2Ca3Cu4−yZnyO12−δ (y=0, 1.0, 2.0, 3.0, 3.5) superconductor with four ZnO2 planes is reported. The structure of the material remains tetragonal for all Zn doping concentration. The substitution of Zn at CuO2 planar site was carried out following Cu0.5Tl0.5Ba2Ca3Cu4−yZnyO12−δ (y=0, 1.0, 2.0, 3.0, 3.5) formula. Contrary to all previous studies of Zn doping in all copper oxide high temperature superconductors, the zero resistivity critical temperature Tc(R=0), critical current density and quantity of diamagnetism increase with increased Zn concentration. The onset temperature of superconductivity in these samples was observed at 128 K and Tc(R=0) at 122 K for y=3.5. The volume of the unit cell observed through X-ray diffraction scan is found to decrease with increase Zn doping; promoting an increase in Fermi vector KF and effective density of states which results in enhanced superconductivity parameters. The synthesis of Cu0.5Tl0.5Ba2Ca3Cu4−yZnyO12−δ material by this method is highly reproducible.