The g-Factor of Ferromagnetic Spinels

The ferromagnetic resonance in Ni-Zn and Mn-Zn binary ferrites and nickel ferrite aluminates have been studied as a function of composition at three wavelengths from 1 cm to 3.2 cm. After studying the size effect of resonance phenomenon, apparent g-factor and line width were obtained at three frequencies as a function of composition. Then concerning the internal field in the specimen, the frequency independent g-factors were obtained from the data of three frequencies. It shows a monotonous decrease in Ni-Zn binary ferrites, while it remains constant in Mn-Zn binary ferrites, and shows interesting changes in nickel ferrite aluminates. These variation of g-factors with composition are well explained by the theory of ferrimagnetic resonance. Investigations were also made into the relation between ferromagnetic resonance and the density of ferrite, and it was found that the porosity in the specimen play a major role in contributing to the frequency dependence of apparent g-factor