Directional frustration of magnetic moments in (U0.50Dy0.50)Ni2B2C

Polycrystalline (U_0.50Dy_0.50)Ni₂B₂C solid solution was prepared and found by X-ray diffraction to crystallize in BCT LuNi₂B₂C-type structure (space group I4/mmm) of the end compounds UNi₂B₂C and DyNi₂B₂C. AC susceptibility and magnetization show paramagnetic behavior down to 6.5 K, with the values θ=−5(5) K and μ_eff=7.7(1) μ_B, compatible with those of the end compounds, and indicate possible cooperative phenomena at lower temperatures. The observed paramagnetism, at variance with antiferromagnetic ordering in (Pr_0.50Dy_0.50)Ni₂B₂C, is attributed to a directional frustration of the magnetic moments on the (U,Dy) site.