High field magnetization study of the Gd2Fe17Hx system

Insertion of light elements such as H, C or N in the R₂Fe₁₇ series (R=rare-earth) has been found to improve some magnetic properties of most ferromagnetic compounds of the series, thus becoming prospective candidates for metal-bonded permanent magnets. For instance spectacular increases of T_c and M_s have been observed upon interstitial insertion. Among the R₂ Fe₁₇H_x series we focused on the Gd compound and we report on high field magnetization measurements that have been carried out on the Gd₂Fe₁₇H_x system (x=0, 3 and 5). The measurements have been performed up to 200 kOe in continuous field. We present the isothermal magnetization curves measured between 2 K and 300 K on powder samples embedded in a resin then aligned under a magnetic field of about 10 kOe in order to get oriented samples. The magnetic anisotropy constants K₁ and K ₂ have been determined taking into account the angular distribution of the grain axes. Their thermal variation as a function of hydrogen concentration is presented. Finally, the observed effect of hydrogen on the iron sublattice anisotropy is compared to that observed in other systems such as R₂Fe₁₄BH_x