Fyzikální ústav Akademie věd ČR

The ferromagnetic layout in solid solutions of Lu₂Fe_17-xSi_x in homogeneity range (x ≤ 3.4) is accompanied by a giant volume magnetostriction, anisotropic with respect to principal axes of the hexagonal crystallographic structure. The volume effect in the ground state of Lu₂Fe₁₇ reaches 1.5% and decays monotonously to 0.9% for x = 3.4, together with the magnetic moment decrease with increasing x. The compounds with x < 2 exhibit invar behavior in a broad temperature range, including room temperature. In U₂Fe_13.6Si_3.4 the volume effect consists of two nearly equal contributions originating from exchange interactions Fe-Fe and U-Fe (0.6% and 0.5%, respectively). It clearly proves that uranium is magnetic in the compound.
The giant spontaneous magnetostriction originates from the competing exchange interactions between Fe atoms in various crystallographic positions.
A.V. Andreev, S. Daniš, Spontaneous magnetostriction of Lu₂Fe_17-xSi_x, Acta Physica Polonica A 113 (2008) 239-242.
A.V. Andreev, S. Daniš, Thermal-expansion anomalies and spontaneous magnetostriction of Lu₂Fe_17-xSi_x intermetallic compounds, J. Magn. Magn. Mater. 320 (2008) e168-e171.doi:10.1016/j.jmmm.2008.02.040
A.V. Andreev, S. Daniš, Spontaneous magnetostriction of R₂Fe_13.6Si_3.4 (R = U, Lu), J. Alloys and Compounds 470 (2008) 24-26, doi:10.1016/j.jallcom.2008.02.058