Dependence of the decoupling temperature of Tl₂Ba₂Ca₂Cu₃O_10-δ (O< δ < 0.15) on applied magnetic field and oxygen stoichiometry

A strong correlation of the decoupling temperature (Td) with applied magnetic field (h and oxygen stoichiometry δ of Tl2Ba2Ca2Cu3O10-δ is reported. The decoupling temperature has been deduced from the disappearance of the intergranular screening currents and is found to obey the following relationship with the amplitude h0 of the external magnetic field, h(t)=h0 sin 2ft; Td=110.54 - 1.17h0+0.026h20 for a δ = 0.009 sample and Td= 98.09 -2.25h0 + 0.06h20 for a δ = 0.141 sample. Both the decoupling temperature (Td) and the intragrain superconducting transition temperature (Tc) decrease with oxygen deficiency (δ), and the former characteristic temperature has a much stronger dependence on δ than the latter. © 1991.