Ferromagnetic Resonance in the Highly Anisotropic Ferrimagnet Gallium Iron Oxide

Resonance measurements at 70 Gc/sec have been made on single crystals of ${\mathrm{Ga}}_{2-x}{\mathrm{Fe}}_x{\mathrm{O}}_3$ ($x\simeq 1.1$) in the temperature range from 1.2 to 360°K. The resonance spectra of this complex and highly anisotropic ferrimagnet can be fitted using three parameters. In the range above 200°K the $g$ value was found to be 1.94±0.04, with an asymptotic value of 1.96 at high temperatures. At 4.2°K the anisotropy fields are 31 and 58 kG along the intermediate and hard magnetic axes, respectively. The same parameters fit the low-field resonance modes where M and H are not parallel, and thus confirm the above values. The observed linewidths are large and anisotropic, varying from approximately 400 to 2400 G.