Reconfigurable heat-induced spin wave lenses

Dzyapko, O.; Borisenko, I. V.; Demidov, V. E.; Pernice, Wolfram; Demokritov, S. O.

doi:10.1063/1.4971829

Cited by 45 publications

(34 citation statements)

References 26 publications

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“…This process is initiated by refraction of the spin wave [28] at the edge of the magnetisation gradient (orange line in Fig. 1a, modified wavelength but no change in the direction of ⃗ for our simple example but important later on) and continues with quasi-adiabatic transformation of the spinwave wavevector [29] (highlighted with coloured arrows at certain positions). This scheme also holds for more general cases in which spin waves propagate under arbitrary angles = ∠( ⃗ , ⃗ ⃗ ext ) with respect to the biasing magnetic field ⃗ ⃗ ext .…”

Section: Resultsmentioning

confidence: 95%

“…We perform our experiments on a 6.6 µm thick ferrimagnetic Yttrium Iron Garnet (YIG) film acting as spin-wave waveguide. The dependency of its saturation magnetisation S on the local temperature ( , ) is well known: S ( ) decreases for increasing [29][30][31][32] (see equation 3 in the methods part). To heat the magnon waveguide, arbitrary intensity distributions are realised via computer-generated holograms.…”

Section: Resultsmentioning

confidence: 99%

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Control of Spin-Wave Propagation using Magnetisation Gradients

Vogel¹,

Aßmann²,

Pirro³

et al. 2018

Sci Rep

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We report that in an in-plane magnetised magnetic film the in-plane direction of a propagating spin wave can be changed by up to 90 degrees using an externally induced magnetic gradient field. We have achieved this result using a reconfigurable, laser-induced magnetisation gradient created in a conversion area, in which the backward volume and surface spin-wave modes coexist at the same frequency. Shape and orientation of the gradient control the conversion efficiency. Experimental data and numerical calculations agree very well. Our findings open the way to magnonic circuits with in-plane steering of the spin-wave modes.

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Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

Control of Spin-Wave Propagation using Magnetisation Gradients

Vogel¹,

Aßmann²,

Pirro³

et al. 2018

Sci Rep

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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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“…49,50,58,69,70. Magnetic non-uniformities can also be created by locally applied magnetic 20,59,71 and electric 72 fields, or optically, 68,[73][74][75] offering an opportunity to study magnonic phenomena in time-varying graded-index magnonic landscapes.Of importance for the present paper, the spatial non-uniformity of any kind (i.e. compositional, geometrical or micromagnetic) also opens up an alternative pathway for the excitation of propagating spin waves by microwaves.…”

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confidence: 99%

Mapping the magnonic landscape in patterned magnetic structures

2017

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We report the development of a hybrid numerical / analytical model capable of mapping the spatially-varying distributions of the local ferromagnetic resonance (FMR) frequency and dynamic magnetic susceptibility in a wide class of patterned and compositionally modulated magnetic structures. Starting from the numerically simulated static micromagnetic state, the magnetization is deliberately deflected orthogonally to its equilibrium orientation, and the magnetic fields generated in response to this deflection are evaluated using micromagnetic software. This allows us to calculate the elements of the effective demagnetizing tensor, which are then used within a linear analytical formalism to map the local FMR frequency and dynamic magnetic susceptibility. To illustrate the typical results that one can obtain using this model, we analyze three micromagnetic systems boasting non-uniformity in either one or two dimensions, and successfully explain the spin-wave emission observed in each case, demonstrating the ubiquitous nature of the Schlömann excitation mechanism underpinning the observations. Finally, the developed model of local FMR frequency could be used to explain how spin waves could be confined and steered using magnetic non-uniformities of various origins, rendering it a powerful tool for the mapping of the graded magnonic index in magnonics.

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Reconfigurable heat-induced spin wave lenses

Cited by 45 publications

References 26 publications

Control of Spin-Wave Propagation using Magnetisation Gradients

Control of Spin-Wave Propagation using Magnetisation Gradients

Graded index lenses for spin wave steering

Mapping the magnonic landscape in patterned magnetic structures

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