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

A novel ternary compound U3Ru4Al12 has been identified in the U-Ru-Al ternary diagram. Single-crystal x-ray diffraction indicates a hexagonal Gd3Ru4Al12-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 (mu(eff) = 2.6 mu(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.