Superconductivity and magnetism in the series R2Fe3Si5 by Mössbauer and magnetization measurements

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Abstract
Members of the R2Fe3Si5 series become either superconducting or magnetically ordered depending on whether the metal atom R( = rare earth, Y or Sc) is diamagnetic or paramagnetic respectively. We have taken Mössbauer effect and magnetization measurements to determine the magnetic state of the iron and the nature of the superconducting electrons. 57Fe Mössbauer measurements on the Sc, Dy and Er compounds all showed two partially resolved, quadrupole split spectra at all temperatures from 300 K to 1.5 K, indicating that there is no resolvable magnetic interaction at the iron site. No major change in the spectrum of Dy2Fe3Si5 was observed in passing through its antiferromagnetic ordering temperature of ∼4 K. Measurements in an applied field of 5.6 T set an upper limit of 0.03 μB for the iron moment in Sc2Fe3Si5. However, measurements at 4.2 K in fields up to 7 T for the Dy compound gave an internal field ∼9% smaller than the applied field and linear with applied field. This corresponds to an induced moment at the iron site of ∼0.07 μB at 7 T applied field. The 161Dy Mössbauer resonance clearly showed the onset of magnetic order around 4 K and the magnetic moment Dy at 1.5 K was found to be 7.0±0.2 μB consistent with the magnetization measurements. The nature of the superconducting electrons in the R2Fe3Si5 series is discussed in the light of available measurements.