Photothermal investigation of magnetostatic modes in yttrium iron garnet at high microwave power levels

Geisau, O. von; Netzelmann, U.; Rezende, S. M.; Pelzl, J.

doi:10.1109/20.104415

Cited by 16 publications

(8 citation statements)

References 7 publications

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“…In other experiments the Faraday rotation or a thermal method that measures the heating of the sample caused by the waves were used to measure the spin wave intensity [8]. All these methods provide a reasonable spatial resolution in measurements of spin wave intensity, but they do not provide temporal resolution, and, therefore, they are not suitable to study fast non-stationary spin wave processes.…”

Section: The Space-and Time-resolved Brillouin Light Scattering Technmentioning

confidence: 99%

“…The threshold of nonlinearity determined by the dissipation parameter is so low that a wide variety of nonlinear wave effects, like formation of envelope solitons [3], modulational [4], decay and kinetic [5] instabilities, can be observed for input microwave powers below 1 W. In films the wave process is easily accessible from the surface. Inductive probes [6,7], thermo-optical methods [8], and Faraday rotation measurements [9] were used to study magnetostatic wave processes in YIG films. It is, however, the recently developed method of space-and time-resolved Brillouin light scattering (BLS) [10,11,12], which provided a major leap in this field due to its high resolution, sensitivity, dynamic range and stability.…”

Section: Introductionmentioning

confidence: 99%

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Linear and nonlinear diffraction of dipolar spin waves in yttrium iron garnet films observed by space- and time-resolved Brillouin light scattering

et al. 2000

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A new advanced space-and time-resolved Brillouin light scattering (BLS) technique is used to study diffraction of two-dimensional beams and pulses of dipolar spin waves excited by strip-line antennas in tangentially magnetized garnet films. The new technique is an effective tool for investigations of two-dimensional spin wave propagation with high spatial and temporal resolution. Linear effects, such as the unidirectional excitation of magnetostatic surface waves and the propagation of backward volume magnetostatic waves (BVMSW) in two preferential directions due to the non-collinearity of their phase and group velocities are investigated in detail. In the nonlinear regime stationary and non-stationary self-focusing effects are studied. It is shown, that non-linear diffraction of a stationary BVMSW beam, having a finite transverse aperture, leads to self-focusing of the beam at one spatial point. Diffraction of a finite-duration (non-stationary) BVMSW pulse leads to space-time self-focusing and formation of a strongly localized two-dimensional wave packet (spin wave bullet). Numerical modeling of the diffraction process by using a variational approach and direct numerical integration of the two-dimensional non-linear Schrödinger equation provides a good qualitative description of the observed phenomena. IntroductionMagnetostatic spin waves in yttrium-iron garnet (YIG) films provide a superb testing ground to study linear and nonlinear wave processes in dispersive, diffractive, and anisotropic media with relatively low dissipation [1,2]. Nonlinear properties of magnetostatic waves in YIG films are therefore anisotropic in the film plane as well. [10,11,12], which provided a major leap in this field due to its high resolution, sensitivity, dynamic range and stability. Using this method it is now possible not only to reproduce all the results obtained previously for stationary wave processes, but also to investigate non-stationary nonlinear wave processes like propagation of intensive wave packets of finite duration and finite transverse aperture (pulse-beams) that are simultaneously affected by dispersion, diffraction, nonlinearity and dissipation [13]. In this paper we present the results of our investigations of linear and nonlinear diffraction of dipolar spin waves propagating in tangentially magnetized YIG films. We first demonstrate the excellent applicability of our method to the observation of well-known linear properties of magnetostatic waves like non-reciprocity of magnetostatic surface wave (MSSW) and reciprocity of backward volume magnetostatic wave (BVMSW) excitations. We discuss non-collinearity of the phase and the group velocity for waves propagating at an arbitrary angle to the in-plane bias magnetic field, and we show the existence of two preferential directions of the wave propagation for the wave beams radiated in a wide angle in the transverse direction. Next we show that our method allows to observe and investigate in detail new nonlinear effects such as the stationary one-dimensional self-f...

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Section: The Space-and Time-resolved Brillouin Light Scattering Technmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Linear and nonlinear diffraction of dipolar spin waves in yttrium iron garnet films observed by space- and time-resolved Brillouin light scattering

et al. 2000

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“…Thus, plane BVMSW modes fulfill the Lighthill criterion [10] for modulational instability in both in-plane directions (SN , 0 and DN , 0), and the effects of self-modulation (leading to the formation of temporal envelope solitons) and self-focusing (leading to the formation of stationary spatial solitons) are allowed for these waves. Both of these effects have been separately observed in YIG films earlier [11][12][13][14].…”

mentioning

confidence: 91%

Observation of Spatiotemporal Self-Focusing of Spin Waves in Magnetic Films

et al. 1998

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The first observation of spatiotemporal self-focusing of spin waves is reported. The experimental results are obtained for dipolar spin waves in yttrium-iron-garnet films by means of a newly developed space-and time-resolved Brillouin light scattering technique. They demonstrate self-focusing of a moving wave pulse in two spatial dimensions, and formation of localized two-dimensional wave packets, the collapse of which is stopped by dissipation. Nonlinear self-focusing of wave beams and pulses is an important phenomenon in physics because it provides a mechanism for localization of wave energy in a small spatial region [1]. In a simple model based on the nonlinear Schrödinger equation with two or three spatial dimensions, self-focusing for certain initial conditions leads to the collapse of the initial wave packet, when the packet amplitude becomes infinite in a finite time [2]. In real physical experiments singularity is, of course, avoided, and the process of collapse is stopped by saturation of nonlinearity and/or by dissipation. The effects of strong self-focusing and of wave collapse have been observed thus far for light waves in nonlinear optics [3], and for nonlinear Langmuir waves in a plasma [4]. The possibility of "light bullets," i.e., stable optical wave pulses strongly localized in space and time by self-focusing, which is stabilized by saturation of nonlinearity at high wave amplitudes, has been suggested by Silberberg [5]. There exists, however, no experimental evidence for this effect in optics, likely because, in optical fibers, diffraction is much stronger than dispersion, and, therefore, both effects cannot be observed simultaneously.In this Letter we report the first experimental observation of spatiotemporal self-focusing of dipolar spin waves and formation of strongly localized two-dimensional wave packets (spin wave bullets) propagating in yttrium-irongarnet (YIG) films. Here the diffraction to dispersion ratio is much smaller than in optical fibers, which makes it possible to observe a simultaneous self-focusing of a propagating spin wave packet along both in-plane directions. The "spin wave bullets" in our experiments are formed as a result of a spatiotemporal self-focusing, similar to the self-focusing effect described in Ref.[5], as our two-dimensional input spin wave packets are self-focused along both in-plane directions (y and z), while propagating along one of them (z). We note, however, that selffocusing of dipolar spin waves in YIG films is stabilized by dissipation, rather than by saturation of nonlinearity, as was suggested for light bullets in Ref. [5].It is well-known [6,7], that, in the absence of dissipation, two-dimensional self-focusing of an input wave packet leads to a packet collapse only if the packet amplitude is sufficiently large for nonlinearity to overcome the effects of diffraction and dispersion. Thus, the twodimensional collapse is critical; i.e., it has an amplitude threshold even in a dissipationless medium.In the presence of dissipation, the amplitude of a ...

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“…The threshold of nonlinearity determined by the dissipation parameter is so low that a wide variety of nonlinear wave effects, like formation of envelope solitons [3], modulational [4], decay and kinetic [5] instabilities, can be observed for input microwave powers below 1 W. In films the wave process is easily accessible from the surface. Inductive probes [6,7], thermooptical methods [8], and Faraday rotation measurements [9] were used to study magnetostatic wave processes in YIG films. It is, however, the recently developed method of space-and time-resolved Brillouin light scattering (BLS) [10,11,12], which provides a major leap in this field due to its high temporal and spatial resolution, sensitivity, dynamic range and stability.…”

mentioning

confidence: 99%

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

Büttner

Bauer

Demokritov

et al. 2000

Journal of Applied Physics

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A new advanced space-and time-resolved Brillouin light scattering technique is used to study diffraction of two-dimensional beams and pulses of dipolar spin waves excited by strip-line antennas in tangentially magnetized garnet films. The technique is an effective tool for investigations of two-dimensional spin wave propagation with high spatial and temporal resolution. Nonlinear effects such as stationary and nonstationary self-focusing are investigated in detail. It is shown, that nonlinear diffraction of a stationary backward volume magnetostatic wave (BVMSW) beam, having a finite transverse aperture, leads to selffocusing of the beam at one spatial point. Diffraction of a finite-duration (non-stationary) BVMSW pulse leads to space-time self-focusing and formation of a strongly localized two-dimensional wave packet (spin wave bullet).Magnetostatic spin waves in yttrium-iron garnet (YIG) films provide a superb testing ground to study linear and nonlinear wave processes in dispersive, diffractive, and anisotropic media with relatively low dissipation [1,2]. The threshold of nonlinearity determined by the dissipation parameter is so low that a wide variety of nonlinear wave effects, like formation of envelope solitons [3], modulational [4], decay and kinetic [5] instabilities, can be observed for input microwave powers below 1 W. In films the wave process is easily accessible from the surface. Inductive probes [6,7], thermooptical methods [8], and Faraday rotation measurements [9] were used to study magnetostatic wave processes in YIG films. It is, however, the recently developed method of space-and time-resolved Brillouin light scattering (BLS) [10,11,12], which provides a major leap in this field due to its high temporal and spatial resolution, sensitivity, dynamic range and stability. Using this method it is now possible not only to reproduce all the results obtained previously for stationary wave processes, but also to investigate non-stationary nonlinear wave processes like propagation of intensive wave packets of finite duration and finite transverse aperture (pulse-beams) that are simultaneously affected by dispersion, diffraction, nonlinearity and dissipation [13]. In this paper we present the results of our investigations of nonlinear diffraction of dipolar spin waves propagating in tangentially magnetized YIG films. We show that our method allows to observe and investigate in detail new nonlinear effects such as the stationary one-dimensional selffocusing effect of microwave excited backward volume magnetostatic wave (BVMSW) beams leading to the formation of spatial spin wave solitons, and the non-stationary spatio-temporal self-focusing effect of two-dimensional propagating wave packets leading to the formation of highly localized quasi-stable wave pulses -spin wave bullets. The last effect was predicted in optics [14], but the first experimental observation of this effect has been reported for the system of magnetostatic spin waves propagating in a YIG film [13].The most interesting case to study two...

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Photothermal investigation of magnetostatic modes in yttrium iron garnet at high microwave power levels

Cited by 16 publications

References 7 publications

Linear and nonlinear diffraction of dipolar spin waves in yttrium iron garnet films observed by space- and time-resolved Brillouin light scattering

Linear and nonlinear diffraction of dipolar spin waves in yttrium iron garnet films observed by space- and time-resolved Brillouin light scattering

Observation of Spatiotemporal Self-Focusing of Spin Waves in Magnetic Films

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

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