Absence of pair breaking effect in Cu0.5Tl0.5Ba2Ca2Cu3−yZnyO10−δ(y = 0, 0.75, 1.5, 2.25, 2.5, 2.65) superconductor

Abstract

We have investigated the existence of any possible pair breaking mechanism in Cu 0.5 Tl 0.5 Ba 2 Ca 2 Cu 0.35 Zn 2.65 O 10− δ superconductor by carrying out post-annealing experiments in nitrogen, oxygen and air atmospheres. This material is grown in tetragonal structure with a and c -axes lengths 3.879 A and 14.581 A; the c -axis length is found to decrease with the increased concentration of Zn in the final compound. The substitution of Zn at CuO 2 planar sites in formula unit Cu 0.5 Tl 0.5 Ba 2 Ca 2 Cu 3− y Zn y O 10− δ has given superconductivity for all the Zn doping concentration of y = 0.75, 1.5, 2.25, 2.5, 2.65. The zero resistivity critical temperature [ T c ( R = 0)], the quantity of diamagnetism and critical current [ I c ( H = 0)] are found to increase with increased Zn doping. In Zn doped samples, post-annealing in air has given a maximum increase in superconducting properties, which showed that final material is optimally doped with carriers in ZnO 2 planes. Since the superconducting properties are marginally suppressed in Zn doped samples by post annealing in O 2 and N 2 atmospheres, it has lead to a definite conclusion that pair breaking mechanism, suggested in previous studies, are absent altogether in our Cu 0.5 Tl 0.5 Ba 2 Ca 2 Cu 0.35 Zn 2.65 O 10− δ superconductor. The synthesis of Cu 0.5 Tl 0.5 Ba 2 Ca 2 Zn 3 O 10− δ superconductor by this method is extremely reproducible.