Sublattice Magnetization in Europium Iron Garnet

The NMR frequencies of Fe⁵⁷ were measured in europium iron garnet between 4.2 and 370^∘{}K. From these data and from measurements of the total magnetization, the magnetizations of the a, d, and c sublattices are calculated. A spin-wave analysis at low temperatures yields D=28.4±0.8 cm^-1, as compared to D=30.0±0.6 cm^-1 for yttrium iron garnet. The temperature dependence of the exchange field acting on Eu⁺³ confirms that interactions between the a and c sublattices are negligible, and shows that JacJcd<0.03. Using, in addition, the information from M\"ossbauer studies on europium garnets, one calculates Jcd=-2.74 cm^-1 and Jcd^'=-0.19 cm^-1, where these parameters represent respectively the exchange with the nearest and next-nearest neighbors on the d sublattice.