The uranium contribution to the magnetism of U-Fe-Si compounds with hexagonal crystal structure of the Th2Ni17 type has been investigated by means of a magnetization study of single crystals that have been grown for the first time. The U contribution to the total magnetic moment is almost negligible. Nevertheless, U strongly influences the magnetic properties, which points to considerable spin and orbital components of the U magnetic moment. A considerable U spin moment is clear from the enhanced Curie temperature of U2Fe13.6Si3.4 (530 K) compared to that of Lu2Fe13.6Si3.4 (470 K). Evidence for a considerable U orbital moment is the strongly enhanced magnetic anisotropy of U2Fe13.6Si3.4 compared to that of Lu2Fe13.6Si3.4. Both the Fe and the U sublattices provide basal-plane type of magnetic anisotropy. The Fe sublattice is characterized by the first anisotropy constant K1 = -0.84MJ/m3 at 4.2K. The U sublattice exhibits nearly the same contribution to K1 and gives rise to a large negative K2, which is manifested by the strong non-linearity of the magnetization curve and the FOMP-like transition at the critical field μ0Hc = 3.3 T. Also, in-plane anisotropy, absent in the Lu compounds, is observed in U2Fe13.6Si3.4 with the easy magnetization axis 〈120〉 (the b-axis in the orthorhombic notation). All these specific features are associated with U atoms on the 2b positions.
- Actinide intermetallics
- Magnetic anisotropy
- Rare-earth intermetallics
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering