Magnetic properties of the (Pr,Dy)Ni2B2C solid solutions

Polycrystalline samples of the (Pr1-xDyx)Ni2B2C solid solutions with x = 0, 0.09, 0.25, 0.50 and 1, were prepared and found by X-ray diffraction to cr ystallize in the BCT LuNi2B2C-type structure (space group I4/mmm) of the en d compounds PrNi2B2C and DyNi2B2C, having close antiferromagnetic (AF) stru ctures. The annealed samples were studied by low-field (LF, 20 Oe) and medi um-field (MF, 1000 Oe) magnetization. MF DC-susceptibility yields paramagne tic values theta and mu(eff) which are compatible with those of the end com pounds. LF magnetization indicates variable AF-ordering behavior across the system, with initial ordering below the respective T-N of 15.0, 14.2, 4.5, 5.0, and 16.3 K. Extreme materials exhibit another transition at T-0 to a fully ordered AF state (<1.8 K for x = 0, 3.5 K for x = 0.04, 10.4 K for x = 1), accounted for by two-step magnetic ordering procedure. It involves in itial ferromagnetic order in the basal planes, followed by a build-up of th e correct AF (alternate) stacking of these planes throughout the samples, c ompleted at the lower transition, T-0. (C) 1999 Elsevier Science B.V. All r ights reserved.