Magnetic Properties of the Hf$_{1 - x}$$R_{x}$Fe$_{6}$Ge$_{6}$ (${R}={\rm Gd}$ and Dy) Compounds

Abstract

We present a study of the magnetic properties and the 57Fe Mossbauer spectra of the Hf1-x R xFe6Ge6, R = Gd and Dy, series. The macroscopic magnetic measurements are consistent with the magnetic independence of the R and Fe sublattices. However, the 57Fe Mossbauer study reveals a more complex magnetic behavior. Specifically, below T t ap 100 K a spin reorientation takes place in HfFe6 Ge6 . The analysis of the corresponding Mossbauer spectra shows that below T t a fraction of the iron moments is canted from the c-axis. The substitution of Hf by Gd or Dy reduces the fraction of canted iron moments. The hyperfine magnetic fields are found to decrease upon the R = Gd or Dy substitution. This effect can be qualitatively explained as a result of the decrease in the hybridization between the d valence states of the R element with the 3d iron states.