Superconductivity Unresponsive to Magnetic Substituents in YBa2(Cu1-xMx)3O7-δ

TLDR: In this paper, the superconducting transition temperature of M substituted YBa 2 (Cu 1- x M x ) 3 O 7-δ is shown to be enhanced by low-temperature annealing in high-pressure oxygen gas, being essentially the same as that of the undoped one up to x = 035.

Abstract: It has been shown that the superconducting transition temperature, T c , of M substituted YBa 2 (Cu 1- x M x ) 3 O 7-δ is markedly enhanced by low-temperature annealing in high-pressure oxygen gas, being essentially the same as that of the undoped one up to x =0035, in cases of M=Fe and Co, while in cases of M=Zn and Ni, T c is almost unchanged by the annealing Since Co replaces only Cu1 and Fe replaces both Cu1 and Cu2, the results indicate that the superconductivity is affected little by the magnetic impurities substituting both the two Cu sites, as in the case of the Y substitutions with rare earth elements, while it is crucially affected by Zn The result may prove that the Cooper pairs do not run on copper ions in this material