Superconducting and normal state properties of oxygen deficient yttrium barium(2) copper(3) oxygen(y) single crystals

Magnetic measurements were carried out on oxygen rich and oxygen deficient single crystals of the high transition temperature superconductor YBa;The results indicate that superconducting properties, such as the Meissner fraction and the transition temperature, are very sensitive to the concentrations of oxygen as well as the ordering of the oxygen atoms. However, the anisotropy in the superconducting properties is not strongly affected by the oxygen stoichiometry. The normal state susceptibility was also not strongly dependent on the oxygen stoichiometry. The results are consistent with the notion that the oxygen atoms occupying the basal plane sites act mainly as reservoirs of charge carriers for the superconducting processes which occur in the copper oxygen planes sandwiching the yttrium site. The concentration of oxygen atoms in the basal plane does not strongly affect the coupling between the copper oxygen planes in adjacent unit cells.