Current-induced magnetization dynamics in two magnetic insulators separated by a normal metal

Skarsvåg, Hans Langva; Bauer, G.; Brataas, Arne

doi:10.1103/physrevb.90.054401

Cited by 7 publications

(7 citation statements)

References 29 publications

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“…Antiparallel spin valves provide a unique opportunity to study and control the dynamic exchange interaction between ferromagnets through a metallic interlayer for tunable magnetic configurations. 33,34 An originally antiparallel configuration is forced by relatively weak external magnetic fields into a non-collinear configuration with a ferromagnetic component. Ferromagnetic resonance (FMR) and Brillouin light scattering (BLS) are two useful experimental methods to investigate the nature and magnitude of exchange interactions and magnetic damping in multilayers.…”

Section: Introductionmentioning

confidence: 99%

“…Taniguchi et al addressed theoretically the enhancement of the Gilbert damping constant due to spin pumping in noncollinear F|N|F trilayer systems, in which one of the magnetizations is excited by FMR while the other is off-resonant, but adopt a role as spin sink. 39 The dynamics of coupled spin valves in which both layer magnetizations are free to move has been computed by one of us 29 and by Skarsvåg et al 33,49 but only for collinear (parallel and antiparallel) configurations. Current-induced high-frequency oscillations without applied magnetic field in ferromagnetically coupled spin valves has been predicted.…”

Section: Introductionmentioning

confidence: 99%

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Magnetization damping in noncollinear spin valves with antiferromagnetic interlayer couplings

2015

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We study the magnetic damping in the simplest of synthetic antiferromagnets, i.e. antiferromagnetically exchange-coupled spin valves in which applied magnetic fields tune the magnetic configuration to become noncollinear. We formulate the dynamic exchange of spin currents in a noncollinear texture based on the spindiffusion theory with quantum mechanical boundary conditions at the ferrromagnet|normal-metal interfaces and derive the Landau-Lifshitz-Gilbert equations coupled by the static interlayer non-local and the dynamic exchange interactions. We predict non-collinearity-induced additional damping that can be sensitively modulated by an applied magnetic field. The theoretical results compare favorably with published experiments.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Magnetization damping in noncollinear spin valves with antiferromagnetic interlayer couplings

2015

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“…The spin accumulation for an FI|N|FI system has been calculated in the macrospin model. 39 The result of this calculation can be directly generalized to the present situation of spatially inhomogeneous spin waves by replacing the macrospin magnetization in each layer with the interface magnetization and substituting the spindiffusion length with a wave-vector-dependent effective spin-diffusion length l sf →l sf (Q) such that…”

Section: B Boundary Conditions and Spin Accumulationmentioning

confidence: 99%

“…We assume that the FMR frequency is much smaller than the electron traversal time, D/d 2 N , and the spin-flip relaxation rate, 1/τ sf . 39 This means the LHS of Eq. (C1) can be disregarded.…”

Section: Appendix A: Dipole Tensormentioning

confidence: 99%

Spin waves in ferromagnetic insulators coupled via a normal metal

Skarsvåg¹,

Kapelrud²,

Brataas³

2014

Phys. Rev. B

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Herein, we study the spin-wave dispersion and dissipation in a ferromagnetic insulator-normal metal-ferromagnetic insulator system. Long-range dynamic coupling because of spin pumping and spin transfer lead to collective magnetic excitations in the two thin-film ferromagnets. In addition, the dynamic dipolar field contributes to the interlayer coupling. By solving the Landau-LifshitzGilbert-Slonczewski equation for macrospin excitations and the exchange-dipole volume as well as surface spin waves, we compute the effect of the dynamic coupling on the resonance frequencies and linewidths of the various modes. The long-wavelength modes may couple acoustically or optically. In the absence of spin-memory loss in the normal metal, the spin-pumping-induced Gilbert damping enhancement of the acoustic mode vanishes, whereas the optical mode acquires a significant Gilbert damping enhancement, comparable to that of a system attached to a perfect spin sink. The dynamic coupling is reduced for short-wavelength spin waves, and there is no synchronization. For intermediate wavelengths, the coupling can be increased by the dipolar field such that the modes in the two ferromagnetic insulators can couple despite possible small frequency asymmetries. The surface waves induced by an easy-axis surface anisotropy exhibit much greater Gilbert damping enhancement. These modes also may acoustically or optically couple, but they are unaffected by thickness asymmetries.

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“…In addition, in such SAF systems the effect of mutual spin-pumping was predicted to influence the linewidth of both modes [25,24]. The effect was observed in symmetric Py/Ru/Py trilayers but only when both layers were saturated at high fields, beyond the spin-flop [28].…”

Section: Introductionmentioning

confidence: 98%

Magnetization dynamics in synthetic antiferromagnets: Role of dynamical energy and mutual spin pumping

et al. 2020

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We investigate magnetization dynamics in asymmetric interlayer exchange coupled Py/Ru/Py trilayers using both vector network analyzer-based and electrically-detected ferromagnetic resonance techniques. Two different ferromagnetic resonance modes, in-phase and out-of-phase, are observed across all three regimes of the static magnetization configurations, through antiparallel alignment at low fields, the spinflop transition at intermediate fields and the parallel alignment at high fields. The non-monotonic behavior of the modes as a function of the external field is explained in detail by analyzing the interlayer exchange and Zeeman energies, and is found to be solely governed by the interplay of their dynamical components. In addition, the linewidths of both modes were determined across the three regimes and the different behaviors of the linewidths versus external magnetic field are attributed to mutual spin pumping induced in the samples. Interestingly, the difference between the linewidths of the out-of-phase and in-phase modes decreases at the spin-flop transition and is reversed between the antiparallel and parallel aligned magnetization states. arXiv:2006.13031v1 [cond-mat.mes-hall]

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Current-induced magnetization dynamics in two magnetic insulators separated by a normal metal

Cited by 7 publications

References 29 publications

Magnetization damping in noncollinear spin valves with antiferromagnetic interlayer couplings

Magnetization damping in noncollinear spin valves with antiferromagnetic interlayer couplings

Spin waves in ferromagnetic insulators coupled via a normal metal

Magnetization dynamics in synthetic antiferromagnets: Role of dynamical energy and mutual spin pumping

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