Magnetostriction and structural distortion in rare-earth intermetallics

On the basis of the special symmetry of the rare-earth site in the Laves-phase cubic compounds $R{T}_{2}$ ($R$ is a rare earth, $T=\mathrm{Fe}, \mathrm{Co}, \mathrm{Ni}$) we predict the occurrence of a structural distortion which vanishes only when [100] is the easy magnetization direction. An extraordinary external strain accompanies the distortion and provides an explanation of the observed size and anisotropy of the magnetostriction in $R{\mathrm{Fe}}_{2}$.