INTRINSIC LOW-FIELD LOSS IN MICROWAVE FERRITES

The off-resonance damping parameter due to the three-magnon splitting process is calculated by extending the theory of intrinsic magnetic re laxation processes. The imaginary part of the diagonal component of th e microwave permeability tensor is found to decrease with increasing i nternal magnetic field and to be proportional to the absolute temperat ure. In magnitude it is somewhat smaller than the subthreshold absorpt ion under parallel pumping, which has a similar physical origin and ha s previously been calculated and verified by experiments. Since the ca lculated magnetic damping occurs in all magnetic materials, it is expe cted to contribute significantly to the insertion loss of many ferrite microwave devices.