Hydrogenation and magnetic properties of amorphous rare-earth-iron (R-Fe) alloys

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Abstract
A novel film synthesis procedure is used to explore the amounts of hydrogen absorbed by amorphous a−R1−xFex alloys with 0≤x≤0.9 and R=Gd, Dy, Tb, Ho, Y. Magnetization and Mössbauer measurements on a-Gd1−xFex:Hy are illustrative of the dramatic magnetic changes produced by the hydrogen. For a-Gd1−xFex:H3 the compensation temperatures are reduced by about 200 K and the Curie temperatures by 50 K. Detailed analysis of magnetization M(T) data for a-GdFe2:Hy with y=0, 1.25, and 3.0 are presented to demonstrate the changes of magnetic moments and exchange parameters. JFe-Fe and JFe-Gd exhibit small percentage decreases with added hydrogen whereas JGd-Gd has a large change, going from ferromagnetic (y=0) to antiferromagnetic coupling (y=3). The iron moment increases by about 10%. The magnetic changes are interpreted in terms of charge transfer as mediated by anionic behavior of the hydrogen.