Temperature-induced changes in the magnetism of Laves phase rare-earth-iron intermetallics by ab initio calculations

Laves $R{\mathrm{Fe}}_{2}$ compounds, where $R$ is a rare earth, exhibit technologically relevant properties associated with the interplay between their lattice geometry and magnetism. We apply ab initio calculations to explore how magnetic properties of Fe in $R{\mathrm{Fe}}_{2}$ systems vary with temperature. We found that the ratio between the orbital magnetic moment ${\ensuremath{\mu}}_{\mathrm{orb}}$ and the spin magnetic moment ${\ensuremath{\mu}}_{\mathrm{spin}}$ increases with increasing temperature for $\mathrm{Y}{\mathrm{Fe}}_{2}, \mathrm{Gd}{\mathrm{Fe}}_{2}, \mathrm{Tb}{\mathrm{Fe}}_{2}, \mathrm{Dy}{\mathrm{Fe}}_{2}$, and $\mathrm{Ho}{\mathrm{Fe}}_{2}$. This increase is significant and it should be experimentally observable by means of x-ray magnetic circular dichroism. We conjecture that the predicted increase of the ${\ensuremath{\mu}}_{\mathrm{orb}}/{\ensuremath{\mu}}_{\mathrm{spin}}$ ratio with temperature is linked to the reduction of hybridization between same-spin-channel states of atoms with fluctuating magnetic moments and to the associated increase of their atomic-like character.