Brillouin Light Scattering and Magnon Wave Vector Distributions for Microwave-Magnetic-Envelope Solitons in Yttrium-Iron-Garnet Thin Films

Brillouin light scattering has been used to measure wave number $k_m$ and wave vector ${\mathbf{k}}_m$ angle distributions for 5 GHz magnetostatic backward-volume-wave envelope solitons in yttrium-iron-garnet thin films. For moderate powers, the data revealed spin waves directly associated with the solitons with $k_m$ values in the $\pm 300\mathrm{rad}/\mathrm{cm}$ range. For high powers, the data showed high $k_m$ spin waves in the 2500–5000 rad/cm range with discrete in-plane ${\mathbf{k}}_m$ directions at 90° and other angles around 90° relative to the soliton propagation direction. These high $k_m$ spin waves provide the first direct evidence of spin wave shedding associated with solitons at high powers.