Formation of guided spin-wave bullets in ferrimagnetic film stripes

The formation of quasi-2D nonlinear spin-wave eigenmodes in longitudinally magnetized stripes of a ferrimagnetic film, so-called guided spin-wave bullets, was experimentally observed by using time- and space-resolved Brillouin light scattering spectroscopy and confirmed by numerical simulation. They represent stable spin-wave packets propagating along a waveguide structure, for which both transversal instability and interaction with the side edges of the waveguide are important. The experiments and the numerical simulation of the evolution of the spin-wave excitations show that the shape of the formed packets and their behavior are strongly influenced by the confinement conditions. The discovery of these modes demonstrates the existence of quasi-stable nonlinear solutions in the transition regime between one-dimensional and two-dimensional wave packet propagation.