Magnetic Study of the Lighter Rare-Earth Ions in the Iron Garnets

The magnetic behavior of the trivalent ions of La, Pr, Sm, and Eu in the iron garnets in the range 0 to 298^∘{}K has been determined, that of the Nd³⁺ ion having been reported earlier. The diamagnetic ion La³⁺ behaves similarly to Y³⁺. An applied field of about 70 kOe appears to produce magnetic saturation of {Y₂Pr} Fe₂{Fe}₃O₁₂ at 4.2^∘{}K, the contribution of the Pr³⁺ ion being 1.6 μB at this temperature. The Sm³⁺ ion introduces large anisotropy but spherical crystals of samarium iron garnet allowed to move freely in the applied field lead to saturation at relatively low fields. The Sm³⁺ ion contributes a moment of 0.14 μB at 0^∘{}K to the net magnetization and behaves similarly to the Pr³⁺ and Nd³⁺ ions at temperatures below 298^∘{}K in that its moment adds to that of the resultant of the iron sublattice moments. Results of measurements of a single-crystal sphere of europium iron garnet are in agreement with those made on a polycrystalline specimen by Villers et al.