An investigation was made of the effects of O vacancies upon the magnetic properties and superconducting transition temperature of high-temperature cuprate superconductors. Starting with the d–p Hamiltonian, the coherent potential approximation was used to account simultaneously for the effects of O vacancies and for the fluctuation-exchange scheme in order to address Cu-site Coulomb interactions. The results showed that the presence of O vacancies weakened the antiferromagnetic spin fluctuations of d-electrons, leading to a lowering of the superconducting transition temperature.

Effects of Oxygen Vacancies in High-Temperature Cuprate Superconductors. D.Matsunaka, E.T.Rodulfo, H.Kasai: Solid State Communications, 2005, 134[5], 355-60