Superconductivity in Ru1-xSr2GdCu2+xO8-y compounds - art. no. 224512

We report on the properties of new ruthenocuprates Ru1-xSr2GdCu2+xO8-y (x = 0, 0.1, 0.2, 0.3, 0.4, and 0.75) that extend the superconductivity found p reviously in RuSr2GdCu2O8(T-c=45 K) to the solid solution with varied Ru/Cu ratios. The compounds have been synthesized in a high-pressure oxygen atmo sphere. The maximum temperature of the superconducting transition is 72 K f or the x=0.3 and 0.4 compositions. The reported behavior of magnetization a t low temperatures can be qualitatively explained assuming a quasi-two-dime nsional character of the superconducting regions in the compounds studied.