155Gd MOSSBAUER EXPERIMENTS ON (Gd0.8RE0.2)l+ Fe4B4

MGssbauer experiments using the 86.5 keV resonance of 1 5 5 ~ d have been performed on Gdl+,Fe4B4 with and without substitution of 20 % of Gd by Nd or Sm. All these alloys are characterized by a very large quadrupolar interaction. At T = 4.2 K, i.e. below the magnetic temperature order, the Miissbauer spectra are quite different for the three alloys, owing to the different direction of the Gd moments with respect to the c-axis. The preferred moment direction for the Gd atoms is imposed by the R.E. atoms in substitution for Gd, and determined by a magnetic anisotropy resulting chiefly from the second order crystal electric field interactions.