High magnetic field study of the Dy2Fe17Hx compounds with x = 0–3.8

Abstract

The Dy2Fe17Hx compounds crystallizing in a hexagonal Th2Ni17-like structure are studied on aligned powder by magnetization measurements carried out in steady (up to 5T) and pulsed (60T) magnetic fields at 4.2–300K. Dy2Fe17 is a ferrimagnet with TC=375K and a spontaneous moment of 16.5μB/f.u. Magnetization curves recorded for two different crystal orientations for Dy2Fe17Hx polycrystalline oriented samples show that the insertion of hydrogen in the Dy2Fe17 crystal lattice significantly modifies the magnetization, Curie temperature and intersublattice exchange interactions of the Dy2Fe17 phase. The high-field behavior of Dy2Fe17 is compared with that of its hydrides derivatives. Despite different types of magnetic anisotropy, the high-field behavior of the hydrides and the parent compound is qualitatively similar. Depending upon the composition, they can exhibit easy plane or else conical type anisotropy as for x=0 and 3, respectively. The low temperature spontaneous magnetization exhibits a moderate composition dependence, it first decreases continuously upon increasing the hydrogen composition up to x=3 then slightly increases for x=3.8 reflecting the Fe sublattice evolution. A mean Fe moment of about 2.1μB is derived for Dy2Fe17H3.8 composition, this magnetization value is close to that of the original Dy2Fe17 compound. It is found that the intersublattice coupling between the Fe and Dy sublattices is reduced as illustrated by the decrease of the nDy–T coefficient from about 3.3 down to 2.82T f.u./μB for Dy2Fe17 and Dy2Fe17H3.8, respectively.