Mössbauer Effect in Yttrium- and in Samarium-Iron Garnets

Magnetic hyperfine fields and electric quadrupole splittings at the tetrahedral (D) and octahedral (A) iron sites in powdered samples of YIG and SmIG have been measured by means of the Mössbauer effect at various temperatures between 85° and 600°K. From the room-temperature Mössbauer spectra it follows that in YIG the magnetization is along the [111] axis, whereas in SmIG the magnetization is in the [110] direction. In SmIG, a Curie temperature of 573.4±0.3°K has been found. From a comparison of the resultant moment of the iron sublattices with the total magnetization of SmIG as measured by Geller et al., a crossover near 300°K is apparent.