a Theory of Nonlinear Effects in Ferromagnetic Metals.

A nonlinear theory of ferromagnetic transmission resonance is presented for the case where the static and microwave magnetic fields are mutually parallel and parallel to the sample surface. The theory is compared to experimental results obtained for iron and nickel, the agreement appears satisfactory. The theory verifies the existence of nonlinear effects which have been observed experimentally in essentially all ferromagnetic metals. The theory further predicts a strong transmission resonance of subharmonic frequency (subharmonic generation) in the transverse direction to the applied fields and at low static field values. The theoretical results are very sensitive to the exchange stiffness constant, and could be used to determine the temperature dependence of the exchange integral for different ferromagnetic metals.