Generation of Propagating Spin Waves From Edges of Magnetic Nanostructures Pumped by Uniform Microwave Magnetic Field

Davies, C. S.; Kruglyak, V. V.

doi:10.1109/tmag.2016.2517000

Cited by 29 publications

(26 citation statements)

References 27 publications

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“…Davies and Kruglyak [19] have shown that it is possible to emit propagating spin waves from an isolated straight edge of a semi-infinite magnetic film. In their geometry, a large nonuniformity in the dynamic demagnetization field triggered the emission of magnetostatic spin waves with a wavelength of several hundred nanometers.…”

Section: Spin-wave Emissionmentioning

confidence: 99%

“…This inhomogeneity launches spin waves with finite wave vector k. The mechanism allows one to emit spin waves in two directions, which is not the case for the spin waves emitted via surface charges in Ref. [19]. Using identical simulation parameters as in Fig.…”

Section: Spin-wave Emissionmentioning

confidence: 99%

“…Alternatives based on wavelength conversions in the vicinity of microwave antennas are also available. Examples include tapered waveguides [14], waveguides coupled to a magnetic antenna [15], grating couplers [16,17], isolated antidots [18,19], and nanowire or nanodisk microwave-to-spin-wave transducers [20,21]. Attaining short-wavelength spin-wave emission with any of these approaches requires patterning of a ferromagnetic layer at the nanoscale.…”

Section: Introductionmentioning

confidence: 99%

“…The wavelength of the emitted spin waves is tunable from a few micrometers to about 100 nm by reorientation of an external bias field. Compared to methods that rely on a modification of the effective magnetic field by nanostructuring [14,[16][17][18][19][20][21], the presented multiferroic system does not require lithography. Finally, we show that dynamic fluctuations of the effective magnetic field at a single-anisotropy boundary suffices for broadband spinwave emission.…”

Section: Introductionmentioning

confidence: 99%

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Tunable Short-Wavelength Spin-Wave Emission and Confinement in Anisotropy-Modulated Multiferroic Heterostructures

Hämäläinen¹,

Brandl

Franke³

et al. 2017

Phys. Rev. Applied

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We report on the generation and confinement of short-wavelength spin waves in a continuous film with periodically modulated magnetic anisotropy. The concept, which is demonstrated for strain-coupled Co 40 Fe 40 B 20 =BaTiO 3 heterostructures, relies on abrupt rotation of magnetic anisotropy at the boundaries of magnetic stripe domains. In combination with an external bias field, this modulation of magnetic anisotropy produces a lateral variation of the effective magnetic field, leading to local spin-wave excitation when irradiated by a microwave magnetic field. In domains with small effective field, spin waves are perfectly confined by the spin gap in neighboring domains. In contrast, standing spin waves in domains with large effective field radiate into neighboring domains. Using micromagnetic simulation, we show that the wavelength of emitted spin waves is tunable from a few micrometers down to about 100 nm by rotation of the bias field. Importantly, the orientation of the wave front remains fixed. We also demonstrate that dynamic fluctuations of the effective magnetic field produce exchange-dominated spin waves at singleanisotropy boundaries. The multiferroic heterostructures presented here enable the use of global excitation fields from a microwave antenna to emit tunable spin waves from a nanometer-wide line source at welldefined locations of a continuous ferromagnetic film.

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Section: Spin-wave Emissionmentioning

confidence: 99%

Section: Spin-wave Emissionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Tunable Short-Wavelength Spin-Wave Emission and Confinement in Anisotropy-Modulated Multiferroic Heterostructures

Hämäläinen¹,

Brandl

Franke³

et al. 2017

Phys. Rev. Applied

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“…Further optimized microwave-to-magnon transducers based on e.g. grating couplers 43 , individual nanomagnets 44 , or sample edges 45 will allow one to excite spin waves with small λ and relatively large v g in the exchange-dominated regime. Still, related decay lengths need to be explored.…”

mentioning

confidence: 99%

Spin waves with large decay length and few 100 nm wavelengths in thin yttrium iron garnet grown at the wafer scale

Maendl

Stasinopoulos

Grundler

2017

Applied Physics Letters

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Using conventional coplanar waveguides (CPWs) we excited spin waves with a wavelength λ down to 310 nm in a 200 nm thin yttrium iron garnet film grown by liquid phase epitaxy. Spin-wave transmission was detected between CPWs that we separated by up to 2 mm. For magnetostatic surface spin waves we found a large nonreciprocity of 0.9 and a high group velocity v g of up to 5.4 km/s. The extracted decay length l d amounted to 0.86 mm. Small λ, high v g and large l d are key figures of merit when aiming at non-charged based signal transmission and logic devices with spin waves.Thin films of the insulating ferrimagnet yttrium iron garnet (YIG) have recently shown to exhibit small spin-wave (SW) damping [1][2][3][4][5][6][7] . A large decay length of up to 0.58 mm was reported for SWs in a 20 nm thick YIG film 3 . In Ref.3 , the films were grown by pulsed laser deposition (PLD) on small substrates of (111) gadolinium gallium garnet (GGG) with a lateral size of about 10 mm × 10 mm. Small damping is important for coherent nanomagnonics, low power consumption and devices such as magnonic holography memory, non-linear cellular networks and SW interferometers 3,[8][9][10][11] . Nonreciprocal characteristics of spin waves further enriches possible logic applications 12 . To scale substrate sizes up, PLD is however very challenging. Here, for instance, magnetron sputtering 13 and liquid phase epitaxy 7,14 are more suitable. Still, for decades, commercially available YIG films grown by liquid phase epitaxy (LPE) had a thickness of 1 µm and beyond 15 . Such thicknesses do not allow for application in nanomagnonics. Recently, a 500 nm thick LPE-grown film was explored with and without nanopatterning 16 . Parameters such as decay length l d , group velocity v g , and nonreciprocity parameter β were however not provided. Note that wafer bonding has already been explored to transfer LPE-grown YIG onto Si substrates to advance integrated photonics 17,18 . Such a route might be interesting for hybrid magnonic devices, and it is timely to explore in detail SW properties of thin YIG grown by LPE.We report on experiments performed on a commercially available YIG film ordered with a thickness t = 200 nm that was grown by LPE on a 3" GGG substrate 20 . Using coplanar waveguides (CPWs) we explored spin-wave propagation over broad frequency and magnetic field regimes. The smallest wavelength λ that we excited by the conventional CPWs amounted to 310 nm. This value is smaller than the wavelengths so far excited via microwave antenna in thin YIG with thicknesses ranging from 20 to 500 nm 3,6,16 . At the same time, we observe modes of higher order compared to earlier publications reporting spin-wave excitation in thin YIG 3,16,21 and thin ferromagnetic metals 22,23 using bare CPWs. The nonreciprocity is found to be pronounced with a parameter β of up to 0.9, much larger compared to 20 nm thick YIG 3 . For magnetostatic surface spin waves (MSSWs) we extract a decay length of 0.86 mm that is a factor of 1.5 larger compared to Ref. [3]. The resul...

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Magnetic Domain Wall Networked Films – Configurational Switching for Tunable Magnetization Dynamics by Perforated Thin Films

Holländer,

Müller,

McCord

2024

Adv Materials Technologies

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Setting the magnetization and its properties in magnetic materials and films is of the utmost fundamental and technological importance for magnetic applications and devices. Magnetic permeabilities in a material are generally defined by the acting magnetic anisotropies together with an applied magnetic field. Here, deterministic switching of the effective dynamic magnetic properties is demonstrated by tunable networks of magnetic domain walls. By perforating magnetic films, a reversible switching between different magnetization states is achieved. Due to the resulting local effective dynamic fields for the changed domain configurations, different zero‐field permeability spectra are attained for the same material structure. Using local configurational magnetic resonances confined by magnetic domain walls, deterministic switchable bimodal dynamic behavior is achieved. Dynamic magnetooptical Kerr microscopy with picosecond temporal resolution proves that the varying periodic magnetic domain configurations are responsible for the dynamic magnetic bistability. In particular, the field‐free precessional magnetic response can be reproducibly switched between 1.3 and 2.3 GHz. The magnetization dynamics can be modified by small interventions in a repeatable manner beyond fixed material and structural properties. The described fundamental mechanism enables to design new energy efficient configurational microwave devices by switching between zero‐field magnetic arrangements.

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Generation of Propagating Spin Waves From Edges of Magnetic Nanostructures Pumped by Uniform Microwave Magnetic Field

Cited by 29 publications

References 27 publications

Tunable Short-Wavelength Spin-Wave Emission and Confinement in Anisotropy-Modulated Multiferroic Heterostructures

Tunable Short-Wavelength Spin-Wave Emission and Confinement in Anisotropy-Modulated Multiferroic Heterostructures

Spin waves with large decay length and few 100 nm wavelengths in thin yttrium iron garnet grown at the wafer scale

Magnetic Domain Wall Networked Films – Configurational Switching for Tunable Magnetization Dynamics by Perforated Thin Films

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