Magnetic Interactions and Distribution of Ions in the Garnets

Since the discovery of the magnetic yttrium and rare earth iron garnets, a systematic investigation has been made of interactions of magnetic ions and the distribution of both magnetic and non-magnetic ionsin the garnets. The results of substitution of the tetravalent tin for Fe3+ ion in yttrium-iron garnet (balanced by substitution of Ca2+ for Y3+ ions) have led to the development by Gilleo of a statistical interaction theory which accounts well for the spontaneous magnetizations and Curie temperatures of the system. This theory has been further strengthened by results from zirconium substituted yttrium-iron garnets and by its successful extension to substituted rare earth iron garnets. In the course of our investigations, many new garnets have been discovered. Several of these have enabled us to observe directly interactions between magnetic ions in dodecahedral and octahedral sites, dodecahedral and tetrahedral sites, octahedral sites only and tetrahedral sites only. The work on the garnets has also already been adequately extensive to lead to the establishment of some rather simple rules pertaining to site preference of ions entering the garnets.