Nonlinear Response of YIG

A small signal study of the second harmonic produced by a small YIG single crystal shows that the anisotropy energy, $K_1$ , is the dominant nonlinear term. This should be true for any ferrimagnet for which ${\mathrm{|K}}_1{\mathrm{/(M}}_3\text{ΔH)|\hspace{0.17em}>\hspace{0.17em}1}$ . At signal levels above saturation a periodic amplitude modulation of the second harmonic level occurs, which may be due to an exchange of energy between longitudinally and transversely radiating modes.