The effect of ellipticity on the direction of spinwave rays

Parallel pumping high signal power microwave radiation is a powerful tool to detect spinwave instabilities, since it allows to infer intrinsic damping properties of ferrimagnets. Several experiments of the last years have shown that the spinwave linewidth does not always follow the law for π/2 magnon scattering. This feature is attributed to the existence of a non zero -component of the spinwave propagation vector . Simple formulas, derived from the dispersion relation are presented in this paper, which evidence the dependence on the spinwave ellipticity of the propagation characteristics of the excited magnons. Also, in the case of three boson processes, the influence of ε on is briefly discussed in the light of the spinwave transit-time theory.