Tomonao Miyadai

Ferrimagnetic Reasonance in Europium-Iron Garnet

Ferrimagnetic reasonance experiment in a single crystal and polycrystalline samples has been carried out by a usual microwave technique. It has been found, for the single crystal, that the temperature variations of the g -factor and the line width are similar to those of erbium-iron garnet (ErIG) except for the existence of a broad maximum in line width at about 200°K. These behaviors agree well with Kittels theory proposed recently. At room temperature, g eff =1.32, Δ H =600 œ (anisotropy in line width having been hardly observed) and K 1 / M s =-400 œ (which is an order of magnitude larger than that of YIG). For polycrystalline samples, g eff is essentially the same as for the single crystal sample. In the absorption curve, a secondary peak appears, below 200°K, in the lower magnetic field side of the main absorption peak. Electronic state of Eu 3+ in the garnet crystal is briefly discussed.