Huge effects of hydrogen absorption on the magnetic properties of ScFe2

The effects of both hydrogen and deuterium absorption are investigated in the ScFe2 intermetallic compound by comparing its intrinsic magnetic properties with those of ScFe2H2.8 and ScFe2D3.2 compounds. It is found that H/D insertion into the hexagonal MgZn2-type crystal lattice of ScFe2 induces a huge increase in spontaneous magnetization, attributed to the volume expansion caused by H/D insertion. The increase in spontaneous magnetization amounts to 104% for ScFe2D3.2. We report for the first time the Curie point of the hydride and deuteride compounds from the analysis of the temperature dependence of the spontaneous magnetization in the frame of Kuz'min's model. Unlike spontaneous magnetization, the magnetic ordering temperature remains almost unaltered upon H insertion for the studied compositions. The ferromagnetic state is robust for all the studied compounds, none of which present antiferromagnetic behavior. No significant difference is observed in the magnetic properties for the two H/D isotopes, the dominant factor being the H/D concentration.