Study of the crystal structure, superconducting and magnetic properties of Ru_1−xFe_xSr₂GdCu₂O₈

Abstract

Samples of the Ru 1-x Fe x Sr 2 GdCu 2 O 8 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 show that the Fe substitution occurs in both Ru and Cu sites. An increase of Fe concentration produces no significant changes in the bond angle Ru-O(3)-Ru, which is a measure of the rotation of the RuO 6 octahedra around the c-axis, and also in the bond angle φ, (Ru-O(1)-Cu), which is a measure of the canting of the RuO 6 octahedra. On the other hand, the bond angle Cu-O(2)-Cu, which is a measure of the buckling of the CuO 2 layer, has a slight tendency to decrease with the increase of Fe content. We found that both ferromagnetic and superconducting transition temperatures are reduced with the increase of Fe concentration. Analysis related to the decay of the superconducting and ferromagnetic states is presented.

Mössbauer study of the (Ru1-xFex)Sr2GdCu2O8-δ system and two of its possible impurities: SrRuO3 and Gd2CuO4

“…The main objective of the present research is to extend and complement previous magnetization results obtained in the ðRu 1Àx Fe x ÞSr 2 GdCu 2 O 8Àδ [22] and to make a cross confirmation, between X-ray and Mössbauer results, of where do the iron atoms go into the structure of the Ru-1212 compound.…”

“…In the magnetization measurements of Escamilla et al [22], the samples showed ferromagnetic transition temperatures that decrease with increasing iron content. The Oxygen content…”

Structural analysis, magnetic and transport properties of the (Ru1−xCox)Sr2GdCu2O8system

“…This behaviour is contrary to Sn and Nb as in Eu-1212 [26]. However, these characteristics are still more intriguing in the Ce, Eu-1222 [27] and Gd-1212 [28] compounds doped with iron where a decreasing of the magnetic moment in the Ru sublattice was observed. It is possible that this increase of the magnetic moment in the Ru/Co site may be due to an enhancement of the antisymmetric exchange, causing the effect that the spins are canted in the ab-plane as has been argued in several intermetallic and ruthenocuprate compounds [20,22,29,30], where a delicate balance among the subtle variations in composition, magnetic structure, and superconducting state may exist.…”