Thickness dependence of spin wave excitations in an artificial square spin ice-like geometry

Li, Yue; Gubbiotti, G.; Casoli, F.; Morley, Sophie A.; Gonçalves, F. J. T.; Rosamond, Mark C.; Linfield, E. H.; Marrows, C. H.; McVitie, S.; Stamps, R. L.

doi:10.1063/1.4978315

Cited by 23 publications

(17 citation statements)

References 38 publications

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“…In conclusion, the above study, apart from its intrinsic interest, has strong implications with regard to artificial spin ice studies involving lattices formed from clusters of the type examined. Unlike previous reports [17][18][19][20], what our study demonstrates is that the spectra of lattices involving weakly coupled clusters of individual macrospins may be viewed as a superposition of the spectra of those macrospins. Using this additivity principle, intensity measurements could then yield the fraction of the individual macrospins presenting different angles with respect to the external magnetic field.…”

Section: Discussioncontrasting

confidence: 75%

“…The static and dynamic response of spin ice lattices is generally rather complex [8,10,14], especially when complex magnetization distributions are concerned, arising from frustrated configurations or arbitrary magnetic field orientations [15,16]. Li et al [17,18] reported Brillouin scattering measurements of spin wave modes in a square spin ice consisting of rectangular blocks for two different directions of the applied magnetic field and multiple thicknesses. However, their simulations were limited to the single and bi-elements elements making up the array.…”

Section: Introductionmentioning

confidence: 99%

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Angular-dependent spin dynamics of a triad of permalloy macrospins

et al. 2019

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We experimentally and theoretically characterize the angular dependent microwave response of three-macrospin-vertex structures that can serve as a node in various spin ice lattices. The macrospins consist of patterned permalloy thin films with an elliptical cross-section together with an in-plane aspect ratio allowing an Ising-like behavior together with bulk modes as low-frequency excitations in the field range of interest. Various branches of the frequency-magnetic field curves display atypical behaviors and discontinuities, together with softening due to macrospin reversals. The overall behavior observed accurately corresponds to a superposition of the spectra of the individual macrospins. The measured ferromagnetic resonance spectra are in good agreement with theoretical modeling. In particular, they reveal a close correlation between the field direction (relative to the individual macrospins), and the corresponding frequency-magnetic field curve; i.e., between the geometry and the magnetic response.

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Section: Discussioncontrasting

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Angular-dependent spin dynamics of a triad of permalloy macrospins

et al. 2019

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“…No strong inter-island coupling exists if external fields are applied along sublattice directions [38]. Fig.…”

Section: Acoustic and Optical Spin-wavesmentioning

confidence: 99%

“…Previously dipole-dipole coupling and collective spin-wave behaviour in ASI proved elusive and avoidedcrossings had not been observed. Interactions were considered too weak to resolve in ASI bulk-modes (BM) [38] or limited to low-power edge-modes (EM) [39,40] which are challenging to detect experimentally due to smaller magnetic volume and imperfect nano-patterned edges although can be improved using ion-beam milling [41]. Simulation of coupled nanomagnets in ASI where inter-island coupling is mediated by spin-wave channels in an exchange-biased underlayer has been demonstrated [42].…”

Section: Introductionmentioning

confidence: 99%

Observation and control of collective spin-wave mode-hybridisation in chevron arrays and square, staircase and brickwork artificial spin ices

Dion¹,

Gartside²,

Vanstone³

et al. 2021

Preprint

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Dipolar magnon-magnon coupling has long been predicted in nano-patterned artificial spin systems. However, observation of such phenomena and related collective spin-wave signatures have until recently proved elusive or limited to low-power edge-modes which are difficult to measure experimentally. Here we describe the requisite conditions for dipolar mode-hybridisation, how it may be controlled, why it was not observed earlier and how strong coupling may occur between nanomagnet bulk-modes. We experimentally investigate four nano-patterned artificial spin system geometries: 'chevron' arrays, 'square', 'staircase' and 'brickwork' artificial spin ices. We observe significant dynamic dipolar-coupling in all systems with relative coupling strengths and avoided-crossing gaps supported by micromagnetic-simulation results. We demonstrate reconfigurable mode-hybridisation regimes in each system via microstate control, and in doing so elucidate the underlying dynamics governing dynamic dipolar-coupling with implications across reconfigurable magnonics. We demonstrate that confinement of the bulk-modes via edge effects play a critical role in dipolar hybridised-modes, and treating nanoislands as a coherently precessing macro-spins or standing spin-waves are insufficient to capture experimentally-observed coupling phenomena. Finally, we present a parameter-space search detailing how coupling strength may be tuned via nanofabrication-dimensions and material properties.

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“…Furthermore, complex dynamics in the high-frequency range have been observed in ASI. It was shown that the specific behavior of individual modes in the spectra can be correlated with the configuration of the magnetic moments in the nanowire legs [16][17][18][19][20][21][22][23][24][25].…”

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confidence: 99%

High-Frequency Dynamics Modulated by Collective Magnetization Reversal in Artificial Spin Ice

et al. 2017

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Spin-torque ferromagnetic resonance (ST-FMR) arises in heavy metal/ferromagnet heterostructures when an alternating charge current is passed through the bilayer stack. The methodology to detect the resonance is based on the anisotropic magnetoresistance, which is the change in the electrical resistance due to different orientations of the magnetization. In connected networks of ferromagnetic nanowires, known as artificial spin ice, the magnetoresistance is rather complex owing to the underlying collective behavior of the geometrically frustrated magnetic domain structure. Here, we demonstrate ST-FMR investigations in a square artificial spin-ice system and correlate our observations to magnetotransport measurements. The experimental findings are described using a simulation approach that highlights the importance of the correlated dynamics response of the magnetic system. Our results open the possibility of designing reconfigurable microwave oscillators and magnetoresistive devices based on connected networks of nanomagnets.

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Thickness dependence of spin wave excitations in an artificial square spin ice-like geometry

Cited by 23 publications

References 38 publications

Angular-dependent spin dynamics of a triad of permalloy macrospins

Angular-dependent spin dynamics of a triad of permalloy macrospins

Observation and control of collective spin-wave mode-hybridisation in chevron arrays and square, staircase and brickwork artificial spin ices

High-Frequency Dynamics Modulated by Collective Magnetization Reversal in Artificial Spin Ice

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