High-field magnetization of R/sub 2/Co/sub 17/ and R/sub 2/Co/sub 17/N/sub x/ compounds

摘要

Magnetization measurements up to 35 tesla have been performed on compounds of the series R/sub 2/Co/sub 17/ and R/sub 2/Co/sub 17/N/sub x/ (R=rare earth) on particles free to be oriented by the applied field. The magnetic coupling in these compounds has been derived from the magnetic isotherms at 4.2 K by means of a two-sublattice model in the mean-field approximation. It is found that the introduction of interstitial nitrogen decreases the intersublattice-coupling. The interpretation of the magnetic isotherms of the nitrided compounds necessitates an extension of the model. At present, it is not clear whether a non-collinear configuration of the sublattice moments in the field-free state can account for the observed behaviour or the anisotropy within the basal plane will have to be considered to understand the results. The effect of the interstitial nitrogen on the saturation magnetization is discussed.