Giant nonlinear damping in nanoscale ferromagnets

Barsukov, I.; Lee, H.K.; Jara, Alejandro; Chen, Y.-J.; Gonçalves, A. M.; Sha, Chengcen; Katine, J. A.; Arias, Rodrigo; Иванов, Б. А.; Krivorotov, I. N.

doi:10.1126/sciadv.aav6943

Cited by 46 publications

(40 citation statements)

References 61 publications

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“…However, the increase of the amplitudes of the dynamical modes leads to their nonlinear coupling. The resulting onset of strong nonlinear relaxation of the energy and the angular momentum of the dominant mode into other spin-wave modes can be described as amplitude-dependent nonlinear damping 17–21 . Starting with the first experiments on the interaction of pure spin currents with the magnetization, this mechanism has become recognized as the main culprit generally preventing complete damping compensation and excitation of coherent magnetization auto-oscillations in spatially extended magnetic systems 6,22 .…”

Section: Introductionmentioning

confidence: 99%

Controlled nonlinear magnetic damping in spin-Hall nano-devices

Divinskiy¹,

Urazhdin

Demokritov³

et al. 2019

Nat Commun

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Large-amplitude magnetization dynamics is substantially more complex compared to the low-amplitude linear regime, due to the inevitable emergence of nonlinearities. One of the fundamental nonlinear phenomena is the nonlinear damping enhancement, which imposes strict limitations on the operation and efficiency of magnetic nanodevices. In particular, nonlinear damping prevents excitation of coherent magnetization auto-oscillations driven by the injection of spin current into spatially extended magnetic regions. Here, we propose and experimentally demonstrate that nonlinear damping can be controlled by the ellipticity of magnetization precession. By balancing different contributions to anisotropy, we minimize the ellipticity and achieve coherent magnetization oscillations driven by spatially extended spin current injection into a microscopic magnetic disk. Our results provide a route for the implementation of efficient active spintronic and magnonic devices driven by spin current.

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Section: Introductionmentioning

confidence: 99%

Controlled nonlinear magnetic damping in spin-Hall nano-devices

Divinskiy¹,

Urazhdin

Demokritov³

et al. 2019

Nat Commun

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“…This leads to a significant decrease of the amplitude of the auto-oscillatory modes as observed in our measurements. In the confined geometry studied in present work, both resonant and non-resonant nonlinear magnon scattering processes are important [100][101][102]. A detailed theoretical model is required for a quantitative explanation of the observed strong temperature dependence of the amplitude of auto-oscillations.…”

Section: B Angular and Temperature Dependence Of Microwave Emissionmentioning

confidence: 93%

Dimensional crossover in spin Hall oscillators

Smith,

Sobotkiewich,

Khan

et al. 2020

Preprint

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Auto-oscillations of magnetization driven by direct spin current have been previously observed in multiple quasi-zero-dimensional (0D) ferromagnetic systems such as nanomagnets and nanocontacts. Recently, it was shown that pure spin Hall current can excite coherent auto-oscillatory dynamics in quasi-one-dimensional (1D) ferromagnetic nanowires but not in quasi-two-dimensional (2D) ferromagnetic films. Here we study the 1D to 2D dimensional crossover of current-driven magnetization dynamics in wire-based Pt/Ni80Fe20 bilayer spin Hall oscillators via varying the wire width. We find that increasing the wire width results in an increase of the number of excited auto-oscillatory modes accompanied by a decrease of the amplitude and coherence of each mode. We also observe a crossover from a hard to a soft onset of the auto-oscillations with increasing the wire width. The amplitude of auto-oscillations rapidly decreases with increasing temperature suggesting that interactions of the phase-coherent auto-oscillatory modes with incoherent thermal magnons plays an important role in suppression of the auto-oscillatory dynamics. Our measurements set the upper limit on the dimensions of an individual spin Hall oscillator and elucidate the mechanisms leading to suppression of coherent auto-oscillations with increasing oscillator size.

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“…A significant body of prior experimental [40][41][42][43][44][45][46][47][48][49][50][51][52][53][54] and theoretical [55][56][57][58] work has been dedicated to studies of spin waves in nanostructures and their interactions with spin currents [59][60][61][62][63][64][65][66][67][68][69][70][71][72][73][74]. These studies typically focus on the frequencies and spatial profiles of the eigenmodes.…”

Section: Introductionmentioning

confidence: 99%

Parametric resonance of spin waves in ferromagnetic nanowires tuned by spin Hall torque

Yang¹,

Jara²,

Duan³

et al. 2021

Preprint

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We present a joint experimental and theoretical study of parametric resonance of spin wave eigenmodes in Ni80Fe20/Pt bilayer nanowires. Using electrically detected magnetic resonance, we measure the spectrum of spin wave eigenmodes in transversely magnetized nanowires and study parametric excitation of these eigenmodes by a microwave magnetic field. We also develop an analytical theory of spin wave eigenmodes and their parametric excitation in the nanowire geometry that takes into account magnetic dilution at the nanowire edges. We measure tuning of the parametric resonance threshold by antidamping spin Hall torque from a direct current for the edge and bulk eigenmodes, which allows us to independently evaluate frequency, damping and ellipticity of the modes. We find good agreement between theory and experiment for parametric resonance of the bulk eigenmodes but significant discrepancies arise for the edge modes. The data reveals that ellipticity of the edge modes is significantly lower than expected, which can be attributed to strong modification of magnetism at the nanowire edges. Our work demonstrates that parametric resonance of spin wave eigenmodes is a sensitive probe of magnetic properties at edges of thin-film nanomagnets.

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Giant nonlinear damping in nanoscale ferromagnets

Abstract: Nonlinear magnon scattering redefines how nanomagnets respond to spin currents.

Cited by 46 publications

References 61 publications

Controlled nonlinear magnetic damping in spin-Hall nano-devices

Controlled nonlinear magnetic damping in spin-Hall nano-devices

Dimensional crossover in spin Hall oscillators

Parametric resonance of spin waves in ferromagnetic nanowires tuned by spin Hall torque

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