Excitation of spin waves during ferromagnetic resonance

Abstract

A non-linear equation is solved which includes the excitation of spin waves by Suhl non-linear coupling and by the scattering of homogeneous precession on inhomogeneities. The solution of this equation takes into account the dependence of the spin-wave frequencies on the degree of excitation of the homogeneous precession and on the degree of excitation of the spin waves. The result of the dependence just quoted is the finality of the amplitudes of spin waves for arbitrary values of the angle of homogeneous precession and the “foldover effect”, connected with hysteresis and discontinuities in the excitation of the spin waves. From the solution it is also apparent that for values of the homogeneous precession amplitude higher than the Suhl critical value the resonance curve splits into two curves, i.e. two groups of spin waves are excited. These two groups differ in frequency by a value of the same order as their relaxation frequency.