Superconductivity and Magnetism in the Series R sub 2 Fe sub 3 Si sub 5 by Moessbauer and Magnetization Measurements

摘要

Members of the R sub 2 Fe sub 3 Si sub 5 series become either superconducting or magnetically ordered depending on whether the metal atom R (= rare earth, Y or Sc) is diamagnetic or paramagnetic respectively. Moessbauer effect and magnetization measurements were made to determine the magnetic state of the iron and the nature of the superconducting electrons. exp 57 Fe Moessbauer measurements on the Sc, Dy and Er compounds all showed two partially resolved, quadrupole split spectra at all temperatures from 300 to 1.5 exp 0 K, indicating that there is no resolvable magnetic interaction at the iron site. No major change in the spectrum of Dy sub 2 Fe sub 3 Si sub 5 was observed in passing through its antiferromagnetic ordering temperature of approx. 4 exp 0 K. Measurements in an applied field of 5.6 T set an upper limit of 0.03 mu /sub B/ for the iron moment in Sc sub 2 Fe sub 3 Si sub 5 . However, measurements at 4.2 exp 0 K in fields up to 7 T for the Dy compound gave an internal field approx. 9% smaller than the applied field and linear with applied field. This corresponds to an induced moment at the iron site of approx. 0.07 mu /sub B/ at 7 T applied field. The exp 161 Dy Moessbauer resonance clearly showed the onset of magnetic order around 4 exp 0 K and the magnetic moment on Dy at 1.5 exp 0 K was found to be 7.0 +- 0.2 mu /sub B/ consistent with the magnetization measurements. The nature of the superconducting electrons in the R sub 2 Fe sub 3 Si sub 5 series is discussed in the light of available measurements. (ERA citation 81:025896)