Magnetization, Structural and Nuclear Quadrupole Resonance Study of

We present the results from a magnetization, structural, and nuclear quadrupole resonance study of the ruthenate-cuprate, RuSr2R2-xCexCu2O10+δ with x=1 and R=Eu. This compound is a superconductor for Ce doping in the range 0.4≤x≤0.8 and displays ferromagnetic order for 0.4≤x≤1.0. We show that the tilting and rotation of the RuO6 octahedra are essentially the same for x=1, x=0.6 and the superconducting antiferromagnet, RuSr2GdCu2O8. However, the moment per Ru in RuSr2EuCeCu2O10+δ is comparable to that observed in RuSr 2EuCu2O8. These results indicate that it is unlikely that the different magnetic order found in RuSr 2R2-xCexCu2O10+δ and RuSr2RCu2O8 (R=Y,Gd,Eu) is due to changes in structurally induced distortions of the RuO6 octahedra as found in the ruthenate compounds (e.g. Sr1-xCaxRuO3). We show that the Cu nuclear quadrupole resonance (NQR) data are similar to those observed in the single CuO2 layer superconductor, La1-xSrxCuO4, where the Cu spin-lattice relaxation rate is dominated by hyperfine coupling within the CuO2 layers and any additional hyperfine coupling from spin fluctuations in the RuO2 layers is small.