“Bright” and “dark” spin wave envelope solitons in magnetic films

The properties of “bright” and “dark” spin wave envelope solitons in dielectric magnetic films are analyzed. It is shown that the nonlinear mechanism responsible for spin wave envelope soliton formation in films is a four-wave interaction between linearly excited spin waves. The coefficients of this interaction are calculated in the case of a tangentially magnetized magnetic film by means of classical Hamiltonian formalism for spin waves. Results of this rigorous calculation are compared with the results of the approximate calculation done by means of the “method of envelopes.” Durations of “bright” and “dark” magnetostatic wave envelope solitons are calculated and compared to the results of experiments performed in tangentially magnetized yttrium-iron garnet (YIG) films