Crystal structure and physical properties of a novel Kondo antiferromagnet: U(3)Ru(4)Al(12).

A novel ternary compound U(3)Ru(4)Al(12) has been identified in the U-Ru-Al ternary diagram. Single-crystal x-ray diffraction indicates a hexagonal Gd(3)Ru(4)Al(12)-type structure for this uranium-based intermetallic. While this structure type usually induces geometrically a spin-glass behaviour, an antiferromagnetic ordering is observed at T(N) = 8.4 K in the present case. The reduced effective magnetic moment of U atoms (µ(eff) = 2.6 µ(B)) can be explained by Kondo-like interactions and crystal field effects that have been identified by a logarithmic temperature dependence of the electrical resistivity, negative values of the magnetoresistivity and particular shape of the Seebeck coefficient.