The intrinsic factors determining Tc in YBa2Cu3O7-δ superconductor

In order to understand the characteristics and mechanism of high-Tc superconducting oxides, the investigation of substitution effects in YBa2Cu3O7-δ has been performed. A large amount of experimental results show that all the orthorhombic crystalline structure, oxygen content, oxidation state of Cu, and metal-semiconductor (insulator) transition etc., are only the extrinsic factors determining Tc. The carrier concentration and the 2D dynamic, short-range antiferromagnetic correlation between Cu atoms in the CuO2 planes are the two intrinsic factors determining the Tc in YBa2Cu3O7-δ. The above conclusions are confirmed further by the substitution effects in Bi-2212 phase compounds. The authors consider that it might be a common character for all kinds of high-Tc superconducting oxides