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

Abstract

Brillouin light scattering has been used to measure wave number k m and wave vector 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 6300 rad͞cm range. For high powers, the data showed high k m spin waves in the 2500-5000 rad͞cm range with discrete in-plane 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. [S0031-9007(98)06546-6]

Brillouin light-scattering observation of the nonlinear spin-wave decay in yttrium iron garnet thin films

“…Both the wave-vector selective BLS experiments in Ref. 19 and the present decay results indicate that this energy goes into spin waves that are pumped by the nonlinear MSW pulse.…”

“…The BLS set up was essentially the same as in Ref. 19, except that there were no wavevector selection slits or irises in the collection optics. With no wave-vector selective apertures, the BLS system collects essentially all of the scattered light within the lens aperture and routes this light signal to the Sandercock Fabry-Perot interferometer.…”

“…20 The Brillouin light-scattering measurements of the wavevector distributions for the magnetic excitations associated with MME solitons in Ref. 19 revealed more than the expected Fourier transform makeup of the nonlinear MME wave packet. These data indicated that soliton formation, propagation, and decay was accompanied by the generation of high-wave-number spin waves.…”

“…1-3 Since these initial reports, a substantial experimental and theoretical effort has been devoted to the study of MME pulse propagation and soliton formation in yttrium iron garnet ͑YIG͒ films. This work has addressed soliton propagation and decay, 4-7 dark solitons, 8,9 soliton order and a power-dependent soliton velocity, 10,11 soliton phase profiles, 12 soliton modeling based on the nonlinear Schrödinger equation and inverse scattering considerations, 13,14 feedback generated solitons, 15,16 the parametric amplification of MME solitons, 17,18 and the Brillouin light-scattering ͑BLS͒ detection of soliton wave-vector distributions, 19 and the spatio-temporal power distributions of soliton bullets. 20 The Brillouin light-scattering measurements of the wavevector distributions for the magnetic excitations associated with MME solitons in Ref.…”

Developments in nano-oscillators based upon spin-transfer point-contact devices

“…In other words, for somewhat complicated reasons that go beyond the scope of this paper, the in-plane component of the dipole-dipole coupling fields must be sufficiently large to give rise to degenerate and half-frequency magnon modes. Given all of these technical reasons, substantial effort has gone into the study and application of nonlinear dynamics in thick YIG films [22]. This state of affairs changed substantially with the advent of the spin torque nanooscillator.…”