Damping of Confined Modes in a Ferromagnetic Thin Insulating Film: Angular Momentum Transfer across a Nanoscale Field-Defined Interface

Adur, Rohan; Du, Chunhui; Wang, Hailong; Manuilov, Sergei A.; Bhallamudi, Vidya; Zhang, Chi; Pelekhov, Denis V.; Yang, Fengyuan; Hammel, P. C.

doi:10.1103/physrevlett.113.176601

Cited by 26 publications

(35 citation statements)

References 32 publications

(63 reference statements)

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“…The solid line is a linear fit, yielding 4πM Ni = 2.3H + 722.9 Gauss. [12][13][14]28] indicates that they are a band of localized modes, closely spaced and thus have overlapping spectra [for details of the spectral separation of the localized modes see the Discussion A section]. For a particle diameter larger than the microstrip dimension, the lower-field peak corresponds to spin wave modes that are confined by the sample, but whose mode amplitudes are globally modified by the particle-field, which we will not further discuss here.…”

Section: Resultsmentioning

confidence: 99%

“…Comparison of ST-FMR spectra in the case of the larger, 5 µm, Ni particle on the 3 µm × 3 µm strip and 3 µm × 6 µm strip, shown in Fig 2(a) and (b) with those from the bare 3 µm-width strip (in the figure inset) reveals an additional peak on the higher field side as expected for localized modes [12][13][14]. We performed micromagnetic modeling [12,[25][26][27] Fig.…”

Section: Resultsmentioning

confidence: 99%

“…We performed micromagnetic modeling [12,[25][26][27] Fig. 3(b), reduced by 50 G to account for the Oersted field and heating from I DC (determined by the shift of the quasi-uniform mode).…”

Section: Resultsmentioning

confidence: 99%

“…3(c). To identify the localized modes resonances, we performed micromagnetic modeling [12,[25][26][27] at θ = 70 ○ , using a value of 4πM eff = 8.7 kG, determined from the in-situ Py/Pt film (both at I DC = 0). For a Py thickness of 5 nm, the four lowest-energy localized modes are three width modes (n = 1, 2, 3) [13] and one higher-order length mode (n = 1, m = 2).…”

Section: (C)] the Broad Peak Observed From Localized Modesmentioning

confidence: 99%

“…Localized spin wave modes, confined by the strongly inhomogeneous dipole magnetic field of a nearby scanned micromagnet, have been demonstrated in ferromagnetic resonance force microscopy (FMRFM) for both imaging and studies of magnetization dynamics at * hammel@physics.osu.edu the nanoscale [12][13][14]. Using magnetic field-localization to define the eigen-modes of a spin-Hall oscillator offers a new approach to the study of spin-Hall torque physics, and multi-mode interactions.…”

Section: Introductionmentioning

confidence: 99%

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Engineering the Spectrum of Dipole Field-Localized Spin-Wave Modes to Enable Spin-Torque Antidamping

Zhang

Manuilov

et al. 2017

Phys. Rev. Applied

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Auto-oscillation of a ferromagnet due to spin-orbit torques in response to a dc current is of wide interest as a flexible mechanism for generating controllable high frequency magnetic dynamics. However, spin wave mode degeneracies and nonlinear magnon-magnon scattering impede coherent precession. Discretization of the spin wave modes can reduce this scattering. Spatial localization of the spin wave modes by the strongly inhomogeneous dipole magnetic field of a nearby spherical micromagnet provides variable spatial confinement, thus offering the option of systematic tunability of magnon spectrum for studying multi-mode interactions. Here we demonstrate that field localization generates a discrete spin wave mode spectrum observable as a series of well-resolved localized modes in the presence of imposed spin currents arising from the spin Hall effect (SHE) in a permalloy/platinum (Py/Pt) microstrip. The observation of linewidth reduction through damping control in this micromagnetically engineered spectrum demonstrates that localized modes can be controlled efficiently, an important step toward continuously tunable SHE driven auto-oscillators.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…We performed micromagnetic modeling [12,[25][26][27] Fig. 3(b), reduced by 50 G to account for the Oersted field and heating from I DC (determined by the shift of the quasi-uniform mode).…”

Section: Resultsmentioning

confidence: 99%

Section: (C)] the Broad Peak Observed From Localized Modesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Engineering the Spectrum of Dipole Field-Localized Spin-Wave Modes to Enable Spin-Torque Antidamping

Zhang

Manuilov

et al. 2017

Phys. Rev. Applied

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Ferromagnetic Resonance Force Microscopy: Spectroscopy on the Nano-Scale

White

Hammel

2016

Microsc Microanal

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Magnetic heterostructures are commonly employed in the growing field of spintronics which utilizes spin transport in materials systems that combine ferromagnetic (FM) materials and normal, or non-magnetic, metals (NM). However, an understanding of how spin is accumulated and transported across these interfaces between two dissimilar materials is needed in order to improve and implement nano-scale structures for future spintronic applications. An equally important question is how magnetic properties such as the local internal field vary spatially in devices. Simulations have shown that variations in the anisotropy fields in a permalloy (Py) film can have large impacts on the linewidth measured by ferromagnetic resonance (FMR), determined by the length scales over which the anisotropy varies [1]. With the linewidth being an important figure of merit for FM devices, this fact motivates the need for a tool that can study dynamical magnetic properties on relevant length scales. Conventional FMR is a powerful technique for studying the internal fields in a FM. However, due its use of global excitation methods combined with detection that is insufficiently sensitive to measure small volumes, it cannot map varying internal fields with the needed spatial resolution. Ferromagnetic resonance force microscopy (FMRFM), a powerful tool for microscopic study of magnetic properties in FM films, addresses these issues and provides a strong complement to conventional FMR. This technique uses a micromagnetic particle attached near the end of a cantilever that interacts with the nearby volume of a FM. Due to the strong spin-spin interactions in a FM, the excitations of a FM are collective modes whose typically large spatial extent limits spatial resolution.

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Spin–Orbit Torque Nano-oscillators by Dipole-Field-Localized Spin Wave Modes

Zhang¹,

Lee²,

Pu³

et al. 2021

Nano Lett.

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We demonstrate a high-quality spin−orbit torque nanooscillator comprised of spin wave modes confined by the magnetic field by the strongly inhomogeneous dipole field of a nearby micromagnet. This approach enables variable spatial confinement and systematic tuning of magnon spectrum and spectral separations for studying the impact of multimode interactions on auto-oscillations. We find these dipole-field-localized spin wave modes exhibit good characteristic properties as auto-oscillatorsnarrow line width and large amplitudewhile persisting up to room temperature. We find that the line width of the lowest-lying localized mode is approximately proportional to temperature in good agreement with theoretical analysis of the impact of thermal fluctuations. This demonstration of a clean oscillator with tunable properties provides a powerful tool for understanding the fundamental limitations and line width contributions to improve future spin-Hall oscillators.

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Damping of Confined Modes in a Ferromagnetic Thin Insulating Film: Angular Momentum Transfer across a Nanoscale Field-Defined Interface

Cited by 26 publications

References 32 publications

Engineering the Spectrum of Dipole Field-Localized Spin-Wave Modes to Enable Spin-Torque Antidamping

Engineering the Spectrum of Dipole Field-Localized Spin-Wave Modes to Enable Spin-Torque Antidamping

Ferromagnetic Resonance Force Microscopy: Spectroscopy on the Nano-Scale

Spin–Orbit Torque Nano-oscillators by Dipole-Field-Localized Spin Wave Modes

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