MAGNETIC-PROPERTIES OF DYFE2H2 FROM FE-57, DY-161 MOSSBAUER-EFFECT AND MAGNETIZATION MEASUREMENTS

A single phase stable hydride with nominal composition DyFe 2H2 is shown to have the cubic C15 Laves structure with a 5% larger lattice constant. 57Fe Mössbauer spectra show two sites with nearly equal population and with different isomer shifts and hyperfine fields. Based on the average hyperfine field at 4.2 K, an Fe moment of approximately 1.6 μB is estimated. From the 161Dy data at 4.2 K, which show a single site, a nearly free-ion moment of 9.8 μB is determined. Relaxation effects in the 161Dy spectra above 77 K, combined with a sharp decrease in the moment with increasing temperature, imply a weakening of the Dy-Fe magnetic coupling induced by the presence of the hydrogen.