Crystal field in amorphous rare-earth--iron alloys

Iron-57 M\"ossbauer absorption measurements and computer calculations show the crystalline electric field to be sharply defined in amorphous metals and alloys. Above the Curie point of amorphous rare-earth-iron compounds we observe a well-defined quadrupole splitting, but in the ferromagnetic phase there is no spectroscopic structure. Computer calculations based on a recent model of the magnetism of rare-earth-transition-metal compounds yield both the paramagnetic doublet and the ferromagnetic flat spectrum.