Suppression of anti-ferromagnetism by enhanced solubility of Ni in Cu1-xTlxBa2Ca2Cu3-yNiyO10-δ (y=0, 0.5, 1.0, 1.5) superconductor

Enhanced solubility of Ni inCuO(2) planes of Cu1-xTIxBa2Ca2CU3O10-delta has been observed. The main objective of ferromagnetic Ni substitution in Cu1-xTIxBa2Ca2Cu3O10-delta 0 superconductor at Cu sites was to reduce any possible anti-ferromagnetic order existing in the inner CuO2 planes(IP);this anti-ferromagnetism is suggested to be suppressing the zero resistivity critical temperature [T-c (R = 0)]. If the anti-ferromagnetic order has some role in bringing about superconductivity at a particular temperature, the doping of ferromagnetic Ni would destroy it and hence the superconductivity. Our studies have shown that the doping of 50% ferromagnetic Ni at Cu sites in CuO2 planes does not destroy the superconductivity; most likely reasons for the enhanced superconductivity have also been discussed. The increased doping of Ni beyond 50% destroys superconductivity and the final material becomes perfect insulator. These studies have suggested that Ni possibly breaks the anti-ferromagnetism existing in the inner CuO2 planes, and the critical temperature is not suppressed very much. The post-annealing experiments demonstrated that the magnitude of diamagnetism is enhanced when carriers are optimum in CuO2 planes. These experiments have contradicted the previous notion of non-uniform doping of inner (IP) and outer planes (OP) as a source of suppression of [T-c (R = 0)] of final compound. These experiments have also manifested that the superconductivity and ferromagnetism can co-exist. (c) 2007 Elsevier B.V. All rights reserved.