Nonlinear Spinwaves in One- and Two-Dimensional Magnetic Waveguides

We discuss the spatial and temporal distribution of linear and non- linear spinwave excitations in two-dimensional films and in quasi-one-dimensional waveguides made of yttrium-iron garnet (YIG). The reported experiments were performed using the recently developed space- and time-resolved Brillouin light scattering technique. We report experiments on the propagation and diffraction of two-dimensional beams and pulses of dipolar spinwaves (backward-volume magne- tostatic waves (BVMSW)) excited in tangentially magnetized YIG films. In the nonlinear regime, stationary and nonstationary self-focusing effects are observed. Diffraction of a stationary BVMSW beam, having a finite transverse aperture, leads to self-focusing at one spatial point. Diffraction of a finite duration (non-stationary) BVMSW pulse-beam leads to space-time self-focusing and formation of strongly lo- calized two-dimensional wave packets - spinwave bullets. The mode properties are illustrated by collision experiments of both quasi-one-dimensional spinwave envelope solitons and of two-dimensional spinwave bullets. Numerical modeling of the diffrac- tion process using a direct numerical integration method of the two-dimensional nonlinear Schrodinger equation provides a good qualitative explanation of the ob- served phenomena.