Exchange resonances in gadolinium iron garnet at 24.000 MHz

Abstract

Ferrimagnetic resonance was experimentally studied in single crystals of gadolinium iron garnet at 24,000 Mc in the vicinity of the magnetic compensation point at Tc = + 13 C. The two modes of resonance corresponding to the normal and abnormal directions of precession of the coupled Fe and Gd sublattices were observed and the results compared with a theory which includes the effect of the susceptibility of the Gd. From these measurements, the exchange field at T/sub c/ was found to be 231,000 Oe, in excellent agreement with magnetization data. In addition, information on (g/sub Fe/ g/sub Gd/) and the crystalline anisotropy were obtained. In a one degree region around the compensation temperature additional modes of resonance were observed. Each of these resonances corresponds to the Fe and Gd sublattices aligned along a (111) direction which is not parallel to the external magnetic field. (auth)