Neutron diffraction study of Nd-substituted FeSr2YCu2O6+δ magnetic superconductor

FeSr2YCu2O6+δ with tetragonal Ba2YCu3O6+δ-type structure exhibits superconductivity around 60 K, only when it is annealed in reduced atmosphere and subsequently in oxidized atmosphere. However, FeSr2NdCu2O6+δ with the substitution of lanthanoid with large ionic radius for Y do not exhibit superconductivity even if it is annealed in the same process as superconducting FeSr2YCu2O6+δ. We have performed neutron powder diffraction of the FeSr2Y1−xNdxCu2O6+δ solid solution system to investigate the effect of the Nd substitution on structure and superconductivity. The structure analysis indicates that the disorder of Sr and Nd, of oxygen on double superconducting CuO2 sheets and of Cu and Fe prevents exhibiting superconductivity in the Nd-substituted system.