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Open accessJournal ArticleDOI: 10.1103/PHYSREVLETT.126.097202

Controlling the Nonlinear Relaxation of Quantized Propagating Magnons in Nanodevices

02 Mar 2021-Physical Review Letters (American Physical Society (APS))-Vol. 126, Iss: 9, pp 097202-097202
Abstract: Relaxation of linear magnetization dynamics is well described by the viscous Gilbert damping processes. However, for strong excitations, nonlinear damping processes such as the decay via magnon-magnon interactions emerge and trigger additional relaxation channels. Here, we use space- and time-resolved microfocused Brillouin light scattering spectroscopy and micromagnetic simulations to investigate the nonlinear relaxation of strongly driven propagating spin waves in yttrium iron garnet nanoconduits. We show that the nonlinear magnon relaxation in this highly quantized system possesses intermodal features, i.e., magnons scatter to higher-order quantized modes through a cascade of scattering events. We further show how to control such intermodal dissipation processes by quantization of the magnon band in single-mode devices, where this phenomenon approaches its fundamental limit. Our study extends the knowledge about nonlinear propagating spin waves in nanostructures which is essential for the construction of advanced spin-wave elements as well as the realization of Bose-Einstein condensates in scaled systems.

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Topics: Magnon (60%), Spin wave (57%), Relaxation (physics) (56%) ... show more
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5 results found


Open accessJournal ArticleDOI: 10.1063/5.0019328
Abstract: This paper provides a tutorial overview over recent vigorous efforts to develop computing systems based on spin waves instead of charges and voltages Spin-wave computing can be considered as a subfield of spintronics, which uses magnetic excitations for computation and memory applications The tutorial combines backgrounds in spin-wave and device physics as well as circuit engineering to create synergies between the physics and electrical engineering communities to advance the field towards practical spin-wave circuits After an introduction to magnetic interactions and spin-wave physics, all relevant basic aspects of spin-wave computing and individual spin-wave devices are reviewed The focus is on spin-wave majority gates as they are the most prominently pursued device concept Subsequently, we discuss the current status and the challenges to combine spin-wave gates and obtain circuits and ultimately computing systems, considering essential aspects such as gate interconnection, logic level restoration, input-output consistency, and fan-out achievement We argue that spin-wave circuits need to be embedded in conventional CMOS circuits to obtain complete functional hybrid computing systems The state of the art of benchmarking such hybrid spin-wave--CMOS systems is reviewed and the current challenges to realize such systems are discussed The benchmark indicates that hybrid spin-wave--CMOS systems promise ultralow-power operation and may ultimately outperform conventional CMOS circuits in terms of the power-delay-area product Current challenges to achieve this goal include low-power signal restoration in spin-wave circuits as well as efficient spin-wave transducers

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Topics: Benchmark (computing) (51%)

61 Citations


Open accessJournal ArticleDOI: 10.3390/MAGNETOCHEMISTRY7060081
03 Jun 2021-Magnetochemistry
Abstract: Magnonic crystals and gratings could enable tunable spin-wave filters, logic, and frequency multiplier devices. Using micromagnetic models, we investigate the effect of nanowire damping, excitation frequency and geometry on the spin wave modes, spatial and temporal transmission profiles for a finite patterned nanograting under external direct current (DC) and radio frequency (RF) magnetic fields. Studying the effect of Gilbert damping constant on the temporal and spectral responses shows that low-damping leads to longer mode propagation lengths due to low-loss and high-frequency excitations are also transmitted with high intensity. When the nanowire is excited with stronger external RF fields, higher frequency spin wave modes are transmitted with higher intensities. Changing the nanowire grating width, pitch and its number of periods helps shift the transmitted frequencies over super high-frequency (SHF) range, spans S, C, X, Ku, and K bands (3–30 GHz). Our design could enable spin-wave frequency multipliers, selective filtering, excitation, and suppression in magnetic nanowires.

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Topics: Radio frequency (54%), Frequency multiplier (54%), Magnetization dynamics (53%) ... show more

2 Citations


Open accessJournal ArticleDOI: 10.1016/J.JMMM.2021.168690
Sławomir Mamica1Institutions (1)
Abstract: In bi-component magnonic crystals (MCs) demagnetizing field occurs around interfaces between a matrix and inclusions. As it is already shown this field strongly influences the spin-wave spectrum including the position and the width of band gaps and their response to the change of the external magnetic field. Here, we show its effect on the reversal of the mode order in the spectrum. The reversal of modes means that the modes which are excited mostly in the material with higher saturation magnetization have the lowest frequency than modes excited in the material with low saturation magnetization. We address this effect to the mode-dependent softening of spin waves resulting from the growing influence of the demagnetizing field while the external magnetic field lowers. The effect gives a possibility of the concentration of spin waves (i.e. the spatial distribution of their energy) in one of the constituent materials (the spin wave is excited much stronger in one material than in the other), the matrix or scattering centres, by the external magnetic field. As an example, we study planar bi-component MCs consisting of cobalt inclusions in permalloy matrix, as well as Py inclusions in Co matrix. We show that in both cases lowering external magnetic field drives down in the spectrum these modes which are excited mostly in Co. Moreover, the concentration of such modes in Co is enhanced.

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Topics: Demagnetizing field (64%), Spin wave (57%), Magnetic field (55%) ... show more


Open accessPosted Content
Abstract: Magnonics is a field of science that addresses the physical properties of spin waves and utilizes them for data processing. Scalability down to atomic dimensions, operations in the GHz-to-THz frequency range, utilization of nonlinear and nonreciprocal phenomena, and compatibility with CMOS are just a few of many advantages offered by magnons. Although magnonics is still primarily positioned in the academic domain, the scientific and technological challenges of the field are being extensively investigated, and many proof-of-concept prototypes have already been realized in laboratories. This roadmap is a product of the collective work of many authors that covers versatile spin-wave computing approaches, conceptual building blocks, and underlying physical phenomena. In particular, the roadmap discusses the computation operations with Boolean digital data, unconventional approaches like neuromorphic computing, and the progress towards magnon-based quantum computing. The article is organized as a collection of sub-sections grouped into seven large thematic sections. Each sub-section is prepared by one or a group of authors and concludes with a brief description of the current challenges and the outlook of the further development of the research directions.

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Topics: Magnonics (51%)
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53 results found


Open accessJournal ArticleDOI: 10.1063/1.4899186
Abstract: We report on the design, verification and performance of mumax3, an open-source GPU-accelerated micromagnetic simulation program. This software solves the time- and space dependent magnetization evolution in nano- to micro scale magnets using a finite-difference discretization. Its high performance and low memory requirements allow for large-scale simulations to be performed in limited time and on inexpensive hardware. We verified each part of the software by comparing results to analytical values where available and to micromagnetic standard problems. mumax3 also offers specific extensions like MFM image generation, moving simulation window, edge charge removal and material grains.

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Topics: Software (51%)

1,643 Citations


Open accessJournal ArticleDOI: 10.1063/1.4899186
20 Oct 2014-AIP Advances
Abstract: We report on the design, verification and performance of MUMAX3, an open-source GPU-accelerated micromagnetic simulation program. This software solves the time- and space dependent magnetization evolution in nano- to micro scale magnets using a finite-difference discretization. Its high performance and low memory requirements allow for large-scale simulations to be performed in limited time and on inexpensive hardware. We verified each part of the software by comparing results to analytical values where available and to micromagnetic standard problems. MUMAX3 also offers specific extensions like MFM image generation, moving simulation window, edge charge removal and material grains.

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Topics: Software (51%)

1,543 Citations


Journal ArticleDOI: 10.1038/NATURE05117
28 Sep 2006-Nature
Abstract: Bose–Einstein condensation (BEC), a form of matter first postulated in 1924, has famously been demonstrated in dilute atomic gases at ultra-low temperatures. Much effort is now being devoted to exploring solid-state systems in which BEC can occur. In theory semiconductor microcavities, where photons are confined and coupled to electronic excitations leading to the creation of polaritons, could allow BEC at standard cryogenic temperatures. Kasprzak et al. now present experiments in which polaritons are excited in such a microcavity. Above a critical polariton density, spontaneous onset of a macroscopic quantum phase occurs, indicating a solid-state BEC. BEC should also be possible at higher temperatures if coupling of light with solid excitations is sufficiently strong. Demokritov et al. have achieved just that, BEC at room temperature in a gas of magnons, which are a type of magnetic excitation. Bose–Einstein condensation, the formation of a collective quantum state of identical particles, called bosons, is observed at room temperature in a gas of magnons, which are a type of magnetic excitation. Bose–Einstein condensation1,2 is one of the most fascinating phenomena predicted by quantum mechanics. It involves the formation of a collective quantum state composed of identical particles with integer angular momentum (bosons), if the particle density exceeds a critical value. To achieve Bose–Einstein condensation, one can either decrease the temperature or increase the density of bosons. It has been predicted3,4 that a quasi-equilibrium system of bosons could undergo Bose–Einstein condensation even at relatively high temperatures, if the flow rate of energy pumped into the system exceeds a critical value. Here we report the observation of Bose–Einstein condensation in a gas of magnons at room temperature. Magnons are the quanta of magnetic excitations in a magnetically ordered ensemble of magnetic moments. In thermal equilibrium, they can be described by Bose–Einstein statistics with zero chemical potential and a temperature-dependent density. In the experiments presented here, we show that by using a technique of microwave pumping it is possible to excite additional magnons and to create a gas of quasi-equilibrium magnons with a non-zero chemical potential. With increasing pumping intensity, the chemical potential reaches the energy of the lowest magnon state, and a Bose condensate of magnons is formed.

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Topics: Bose–Einstein condensate (65%), Boson (60%), Magnon (59%) ... show more

654 Citations


Journal ArticleDOI: 10.1016/0022-3697(57)90010-0
H. Suhl1Institutions (1)
Abstract: B loembergen and W ang , as well as D amon , have observed two anomalous effects in the microwave absorption of ferromagnets at high signal powers: a saturation of the usual resonance at powers far below those thought to be necessary on the basis of the observed relaxation time, and the appearance, at similar signal levels, of a rather broad secondary absorption peak some hundreds of oersteds below the d.c. field required for resonance. It is shown that these effects are connected with two kinds of instability of the uniform precessional motion of the total magnetization against certain spin-wave disturbances. These disturbances will grow, exponentially to begin with, when the signal level exceeds certain threshold values. It turns out to be possible to calculate the new final state attained by the medium in the case of the subsidiary absorption; in this state the uniform precession limits at a fixed value, no matter how large the signal, whereas a narrow range of spin waves is excited to a large nonthermal value which increases steadily with signal power. The susceptibilities calculated in the new regime check the experiments quite well. Some predictions of the theory beyond the above-mentioned observations have also been verified. A simplified, less rigorous treatment has already been given elsewhere. In the present paper a more complete theory is developed, with special emphasis on the new state of the medium beyond the threshold.

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Topics: Ferromagnetic resonance (51%), Spin wave (50%)

637 Citations


Open accessJournal ArticleDOI: 10.1038/NCOMMS5700
Abstract: An attractive direction in next-generation information processing is the development of systems employing particles or quasiparticles other than electrons--ideally with low dissipation--as information carriers. One such candidate is the magnon: the quasiparticle associated with the eigen-excitations of magnetic materials known as spin waves. The realization of single-chip all-magnon information systems demands the development of circuits in which magnon currents can be manipulated by magnons themselves. Using a magnonic crystal--an artificial magnetic material--to enhance nonlinear magnon-magnon interactions, we have succeeded in the realization of magnon-by-magnon control, and the development of a magnon transistor. We present a proof of concept three-terminal device fabricated from an electrically insulating magnetic material. We demonstrate that the density of magnons flowing from the transistor's source to its drain can be decreased three orders of magnitude by the injection of magnons into the transistor's gate.

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Topics: Magnon (67%), Magnonics (54%), Quasiparticle (52%) ... show more

544 Citations


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