Magnetic behavior of uranium in strong ferromagnetic matrix of 3d-metals

Alexander V. Andreev
Institute of Physics of Academy of Sciences, Prague, Czech Republic
Institute for Materials Research, Tohoku University, Sendai, Japan

Uranium does not form binary compounds with Fe and Co having the 2-17 stoichiometry, however, the hexagonal Th2Ni17-type crystal structure, which is characteristic for R2T17 with heavy rare-earth metals, can be stabilized by substitution of a small amount of third element, e.g. Si, for the T metal. In U2(T,Si)17 compounds, where a strong 5f-3d electron hybridization causing a delocalization of the 5f electrons is expected, the magnetic ordering of the U sublattice seems to be hardly possible. However, the single-crystal study of magnetic anisotropy U2(T,Si)17 compounds together with isostructural compounds of non-magnetic Lu gives arguments pointing to the magnetic contribution from the U sublattice. Results of magnetization studies of single crystals of U2(Fe1-xCox)13.6Si3.4 and U2Co17-xSix are discussed.