Raman transport and magnetization study of the RuSr2R2−xCexCu2O10+δ (R=Gd,Eu) high-temperature superconducting cuprates

Abstract

We present the results from a Raman transport and magnetization study on RuSr2R2−xCexCu2O10+δ. This compound has been shown to exhibit the coexistence of superconducting and magnetic order. Unlike the other superconducting ruthenate cuprate, RuSr2RCu2O8, RuSr2R2−xCexCu2O10+δ contains a significant ferromagnetic component. We find that the peak in the low-field zero-field-cooled magnetization data increases with increasing Ce concentration. This increase is mirrored by an increase in the saturation magnetization at 9.5 kG. However, there is no direct correlation between these increases and the superconducting transition temperature. Furthermore, there are no well-defined changes in either the resistance or the thermopower data that can be correlated with the magnetic-ordering transition. A simple explanation for the increase in the saturation magnetization at 9.5 kG is that, similar to SrRuO3, the RuO2 layers in RuSr2R2−xCexCu2O10+δ are itinerant ferromagnetic metals. We show that the RuSr2R2−xCexCu2O10+δ transport data can be interpreted in terms of both the resistance and thermopower being dominated by the CuO2 layers. In this interpretation, the RuO2 layers only affect the resistance in the CuO2 layers via exchange coupling and possible spin scattering. The Raman spectra is essentially the same as that found in RuSr2RCu2Oδ and there is no evidence of Raman modes that can be associated with the R2−xCexO2 substructure.

Source-reported materials — not catalogue approval

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