Spatial and spatiotemporal self-focusing of spin waves in garnet films observed by space- and time-resolved Brillouin light scattering

A new advanced space- and time-resolved Brillouin light scattering techniqu e is used to study diffraction of two-dimensional beams and pulses of dipol ar spin waves excited by strip-line antennas in tangentially magnetized gar net films. The technique is an effective tool for investigations of two-dim ensional spin wave propagation with high spatial and temporal resolution. N onlinear effects such as stationary and nonstationary self-focusing are inv estigated in detail. It is shown that nonlinear diffraction of a stationary backward volume magnetostatic wave (BVMSW) beam, having a finite transvers e aperture, leads to self-focusing of the beam at one spatial point. Diffra ction of a finite-duration (nonstationary) BVMSW pulse leads to space-time self-focusing and formation of a strongly localized two-dimensional wave pa cket (spin wave bullet). (C) 2000 American Institute of Physics. [S0021-897 9(00)30808-8].