Internal magnetic fields in Yttrium iron garnet

Abstract

The internal hyperfine field of a ferromagnetic yttrium iron garnet, Y₃Fe₅O₁₂, is determine using Mössbauer spectroscopy. The yttrium iron garnet specimen[s] were prepared by the solid chemical reaction of ultra pure Y₂O₃ and Fe₂O₃ oxides heated to 1380℃ for two hours. The reacted powders were then pressed into pellets which were sintered at 1500℃ for twenty four hours. The crystal structure of the ceramics was determined by X-ray diffraction studies. The Fe⁵⁷ Mössbauer spectra for the yttrium iron garnet appeared to consist of two sextets, due to hyperfine field splitting of the Fe³⁺ nuclides located on the ‘a’ and ‘d’ sites in the garnet structure. Our measurements did not have the resolution which permitted the differentiation of the different types of ‘a’ sites in the garnet structure. The chemical isomer shifts at the ‘a’ and ‘d’ sites were found to be 0.25 m/s and 0.12 mm/s, respectively, while the hyperfine fields at the two sites were found to be 485 KOe and 397 Koe.