Magnetic properties of diluted magnetic ${\mathrm{}(\mathrm{G}\mathrm{d},\mathrm{L}\mathrm{u})\mathrm{}}_2{\mathrm{O}}_3$

The magnetic susceptibility of the diluted magnetic ${\mathrm{Lu}}_{2-x}{\mathrm{Gd}}_x{\mathrm{O}}_3$ $(x=0.06,$ 0.10, 0.22, 0.40, 1.00, 1.40, 1.80) was measured in the temperature range 1.7–295 K. The inverse susceptibility changes slope to a smaller value below 2.2 K for the samples with $x<~\mathrm{0.40.}$ In the cubic ${\mathrm{Lu}}_{0.20}{\mathrm{Gd}}_{1.80}{\mathrm{O}}_3$ the slope increases below 2.8 K. These changes are attributed to the large difference in susceptibility for two cationic sites at low temperatures and to the crystallographic distribution of ${\mathrm{Gd}}^{3+}$ ions. The monoclinic ${\mathrm{Lu}}_{0.20}{\mathrm{Gd}}_{1.80}{\mathrm{O}}_3,$ which was obtained from the stoichiometrically similar cubic phase at 1620 K, has an antiferromagnetic phase transition at 3.4 K. The magnetic-ion distribution for low-concentration samples $(x=0.06,$ 0.10) was studied using an isolated-cluster method in the nearest-neighbor approximation. In these samples a tendency for magnetic-ion cluster formation was found. A random cluster distribution was found to be consistent with the susceptibility data for the sample with $x=\mathrm{0.06.}\mathrm{}$ For the $x=0.10\mathrm{}$ sample the susceptibility calculated with a modified cluster distribution gives the best agreement with the experimental results.