Fundamental characteristics of rare-earth (R) - iron intermetallics R2Fe14B are highly sensitive to the atomic substitutions and interstitial absorption of light elements. We studied a combined influence of the substitutions in the rare-earth sublattice and hydrogen absorption on the magnetization behavior in magnetic fields up to 60 T Er2Fe14B and Tm2Fe14B ferrimagnets chosen for the study showed that the substitution of Nd for Er or Tm increases the saturation magnetization as a result of ferromagnetic ordering of Nd and Fe moments.
Under sufficiently high magnetic fields the magnetic moments rotate and the field-induced ferromagnetic state may be observed. The field at which a transition occurs is related to the strength of the inter-sublattice exchange interaction.
The role of hydrogen is primarily to weaken the inter-sublattice ferrimagnetic coupling so that the reorientation becomes achievable at the available magnetic field strength (in hydrides Tm2Fe14BH5.5 and (Tm0.5Nd0.5)(2)Fe14BH5.5). We analyze the volume dependence of the R-Fe magnetic interaction in R2Fe14B and compare it with other R-Fe compounds.