Effect of interstitial atoms on the effective exchange fields in ferrimagnetic rare-earth and 3d transition metal compounds R2Fe17 and RFe11Ti

The magnetic properties (magnetic ordering temperature, magnetization) of the ferrimagnetic compounds R ₂Fe₁₇ and RFe₁₁Ti, as well as of their hydrides and nitrides, were studied. The hydrogenation-and nitrogenation-induced variation of the exchange fields acting on the rare-earth (RE) ions from both the Fe sublattice and other RE ions was determined, and the dependence of the Curie temperatures of the starting compounds, their hydrides, and nitrides on the de Gennes factor was revealed. It was found that incorporation of light atoms (H, N) into the crystal lattices of RFe₁₁Ti and R ₂Fe₁₇ increases the Curie temperature T _C substantially, increases the Fe-Fe exchange coupling, and decreases the R-R exchange interactions, as well as increases the R-Fe intersublattice exchange under hydrogenation and decreases it under nitrogenation, an effect that can be understood as resulting from the attendant changes in the electronic structure of these compounds and in the indirect exchange interactions. __________ Translated from Fizika Tverdogo Tela, Vol. 45, No. 10, 2003, pp. 1850–1856. Original Russian Text Copyright ? 2003 by Nikitin, Tereshina.