Thresholds of Envelope Soliton Formation for Dipole-Exchange Spin Waves in Yttrium-Iron Garnet Films

Abstract
The power thresholds of spin wave envelope soliton formation from input rectangular radio-pulses of duration T in a thin yttrium-iron garnet (YIG) film were studied experimentally. The measurements were done for strongly dispersive dipole-exchange spin waves in the vicinity of one of the dipole gaps in the spectrum of a film with strongly pinned surface spins. The observed threshold curve P_th = f ( 1/T²) is non-monotonous and has a fine structure consisting of three minima corresponding to the formation of n = 1, 2, and 3 solitons. The observed shape of the threshold curve is explained by the theory of envelope soliton formation where dissipation in the medium is taken into account. The values and positions of the minima on the experimentally measured threshold curve are determined by the dissipation parameter Γ=ΔH which is proportional to the half-linewidth ΔH of ferromagnetic resonance in the experimental YIG film.