Study of the crystal structure, superconducting and magnetic properties of Ru1-xFexSr2GdCu2O8

Samples from the Ru1-xFexSr2GdCu2O8 system with x = 0, 0.025, 0.05, 0.075, 0.1 and 0.2, were prepared and their structural, superconducting and magnetic properties were studied. Rietveld refinement of the x-ray diffraction patterns shows that the Fe substitution occurs at both Ru and Cu sites. An increase of Fe concentration produces no significant changes in the Ru-O(3)-Ru bond angle, which is a measure of the rotation of the RuO6 octahedra around the c-axis, or in the Cu-O(1)-Ru bond angle phi, which is a measure of the canting of the RuO6 octahedra. On the other hand, the Cu-O(2)-Cu bond angle, which is a measure of the buckling of the CuO2 layer, has a slight tendency to decrease with increase of the Fe content. We found that both ferromagnetic and superconducting transition temperatures are reduced with increase of the Fe concentration. Analysis related to the decay of the superconducting and ferromagnetic states is presented.