Control of Spin-Wave Propagation using Magnetisation Gradients

Vogel, Marc; Aßmann, Rick; Pirro, Philipp; Chumak, A. V.; Hillebrands, B.; Freymann, Georg von

doi:10.1038/s41598-018-29191-2

Cited by 69 publications

(39 citation statements)

References 47 publications

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“…Prerequisites for that are well-investigated and understood properties of the particles and thus the possibility to control their behavior. [2][3][4] The scope of our research is the investigation of magnetization dynamics as it provides an opportunity for highly advanced magnetic memory and logic devices. [5][6][7] Magnons or spin-waves, being the elementary excitations of coupled spin systems in solids, have been widely investigated in thin films, [8][9][10] nanostructured multilayers, 11 magnonic crystals, [12][13][14][15] and magnonic waveguides.…”

mentioning

confidence: 99%

“…[26][27][28][29] In most of the cases, spin-waves are investigated using a nonuniform excitation of the structure. 2,4,10,12 When the uniform excitation field is applied to the specimen, it is also possible to excite spin-waves, but only standing spin-waves are expected. 30 A standing spin-wave implies that its nodes remain at the same position in space over the time.…”

mentioning

confidence: 99%

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Non-standing spin-waves in confined micrometer-sized ferromagnetic structures under uniform excitation

Pile

Feggeler

Schaffers

et al. 2020

Applied Physics Letters

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A non-standing character of directly imaged spin-waves in confined micron-sized ultrathin permalloy (Ni 80 Fe 20 ) structures is reported along with evidence of the possibility to alter the observed state by modifications to the sample geometry. Using micromagnetic simulations the presence of the spin-wave modes excited in the permalloy stripes along with the quasi-uniform modes were calculated. The predicted spin-waves were imaged in direct space using time resolved scanning transmission X-ray microscopy, combined with a ferromagnetic resonance excitation scheme (STXM-FMR). STXM-FMR measurements revealed a non-standing character of the spin-waves. Also it was shown by micromagnetic simulations and confirmed with STXM-FMR results that the observed character of the spin-waves can be influenced by the local magnetic fields in different sample geometries.

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confidence: 99%

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confidence: 99%

Non-standing spin-waves in confined micrometer-sized ferromagnetic structures under uniform excitation

Pile

Feggeler

Schaffers

et al. 2020

Applied Physics Letters

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“…To change the wave number and thus the index for the given wave frequency, we need to change the dispersion relation by varying one of the bulk material parameters, or film thickness [11][12][13][14][15] . We then need to choose an isotropic dispersion relation that enables a large change in k, and thus n. This requirement is satisfied in the dipolar-dominated regime, in the forward-volume geometry, where the magnetization is directed normal to the film plane.…”

Section: Theory Of Spin Wave Steering Lensesmentioning

confidence: 99%

“…However, these waveguides may suffer from losses/scattering in bends, and usually have a large spatial footprint. An alternative solution is to steer spin waves via a graded refractive index [11][12][13][14] , which smoothly alters the wave trajectory with minimal reflections 15 . To achieve a graded index for spin waves, one must gradually change a magnonic parameter on a length scale much smaller than the wavelength.…”

Section: Introductionmentioning

confidence: 99%

Graded index lenses for spin wave steering

et al. 2019

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We use micromagnetic modelling to demonstrate the operation of graded index lenses designed to steer forward-volume magnetostatic spin waves by 90 and 180 degrees. The graded index profiles require the refractive index to diverge in the lens center, which, for spin waves, can be achieved by modulating the saturation magnetization or external magnetic field in a ferromagnetic film by a small amount. We also show how the 90 • lens may be used as a beam divider. Finally, we analyse the robustness of the lenses to deviations from their ideal profiles. SUPPLEMENTAL MATERIAL List of Supplementary Animations and their CaptionsAnimation 1 (a) -Wave packet incident on 90 degree lens: Video corresponding to Fig. 6 (a) in the main text, showing the m x component of the wave packet moving through the 90 • lens. Animation 1 (b) -Wave packet incident on 180 degree lens: Video corresponding to Fig. 6 (b) in the main text, showing the m x component of the wave packet moving through the Eaton (180 • ) lens.Animation 2 (a) -90 degree lens as a beam divider: Video corresponding to Fig. 7 (a) in the main text, showing the 90 • lens acting as a ±90 • half-power beam divider. The m x component of the beam is shown. Animation 2 (b) -90 degree lens as a wave packet divider: Video corresponding to Fig. 7 (b) in the main text, showing the 90 • lens acting as a ±90 • half-power beam divider for an incoming wave packet. The m x component of the wave packet is shown.Each animation uses the parameters stated in the main text.

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“…A main aspect of this confinement at relatively low frequencies is the formation of a caustic beam [10][11][12]. Additionally, it has been shown that refractive spin-wave optics can be realized [13][14][15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Direct observation of spin-wave focusing by a Fresnel lens

et al. 2020

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Spin waves are discussed as promising information carrier for beyond complementary metal-oxide semiconductor data processing. One major challenge is guiding and steering of spin waves in a uniform film. Here, we explore the use of diffractive optics for these tasks by nanoscale real-space imaging using x-ray microscopy and careful analysis with micromagnetic simulations. We discuss the properties of the focused caustic beams that are generated by a Fresnel-type zone plate and demonstrate control and steering of the focal spot. Thus, we present a steerable and intense nanometer-sized spin-wave source. Potentially, this could be used to selectively illuminate magnonic devices like nano-oscillators.

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Control of Spin-Wave Propagation using Magnetisation Gradients

Cited by 69 publications

References 47 publications

Non-standing spin-waves in confined micrometer-sized ferromagnetic structures under uniform excitation

Non-standing spin-waves in confined micrometer-sized ferromagnetic structures under uniform excitation

Graded index lenses for spin wave steering

Direct observation of spin-wave focusing by a Fresnel lens

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