Propagating spin waves excited by spin-transfer torque: A combined electrical and optical study

Madami, M.; Iacocca, Ezio; Sani, Sohrab R.; Gubbiotti, G.; Tacchi, S.; Dumas, Randy K.; Åkerman, Johan; Carlotti, G.

doi:10.1103/physrevb.92.024403

Cited by 35 publications

(25 citation statements)

References 32 publications

(45 reference statements)

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“…1 [13,32,42]. In this case, its mode favors to be a propagating spin-wave [13,27,44]. All of these experimental observations confirm the theoretical predictions very well.…”

supporting

confidence: 76%

Reduced spin torque nano-oscillator linewidth using He+ irradiation

Jiang

Khymyn

Chung

et al. 2020

Applied Physics Letters

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We use He + irradiation to tune the nonlinearity, N , of all-perpendicular spin-torque nanooscillators (STNOs) using the He + fluence-dependent perpendicular magnetic anisotropy (PMA) of the [Co/Ni] free layer. Employing fluences from 6 to 20×10 14 He + /cm 2 , we are able to tune N in an in-plane field from strongly positive to moderately negative. As the STNO microwave signal properties are mainly governed by N , we can in this way directly control the threshold current, the current tunability of the frequency, and the STNO linewidth. In particular, we can dramatically improve the latter by more than two orders of magnitude. Our results are in good agreement with the theory for nonlinear auto-oscillators, confirm theoretical predictions of the role of nonlinearity, and demonstrate a straightforward path towards improving the microwave properties of STNOs. DOI: XXXXXX.Spin-torque nano-oscillators (STNOs) are among the most promising candidates for nanoscale broadband microwave generators [1-6] and detectors [7][8][9]. STNOs can generate broadband microwave frequencies ranging from hundreds of MHz to the sub-THz [10-12], controlled by both magnetic fields and dc currents [5,13]. Moreover, the device size can be reduced to a few tens of nanometers, which is of great opportunity for industrial applications. They can also host a range of novel magnetodynamical spin wave modes, such as propagating spin waves of different orders [14,15], and magnetodynamical solitons, such as spin wave bullets [14] and droplets [3].

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“…1 [13,32,42]. In this case, its mode favors to be a propagating spin-wave [13,27,44]. All of these experimental observations confirm the theoretical predictions very well.…”

supporting

confidence: 76%

Reduced spin torque nano-oscillator linewidth using He+ irradiation

Jiang

Khymyn

Chung

et al. 2020

Applied Physics Letters

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“…In spite of this, excitation of 45 coherent propagating spin waves by pure spin currents was achieved only recently. The difficulty was associated with a number of conflicting requirements, which are also known for the traditional devices operated by spin-polarized electric currents [16][17][18][19][20][21][22]. In particular, efficient excitation of single-frequency coherent magnetization oscillations generally requires that they are spatially confined, as was shown for all the demonstrated SHE-and NLSI-based nanooscillators.…”

Section: Excitation Of Propagating Spin Waves By Pure Spin Currentsmentioning

confidence: 99%

“…Since the first demonstration [1][2][3][4][5] of the possibility to excite magnetization dynamics by spin-polarized electric currents due to the spin transfer torque (STT) effect [6,7], dynamic spin torque phenomena have become the subject of intense research [8][9][10][11][12][13][14][15]. The ability to control high-frequency magnetization dynamics by dc currents is promising for the generation of microwave signals [8][9][10][11][12][13][14][15] and propagating spin waves [16][17][18][19][20][21][22][23] in magnetic nanocircuits.…”

Section: Introductionmentioning

confidence: 99%

Magnetization oscillations and waves driven by pure spin currents

et al. 2017

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Recent advances in the studies of pure spin currents -flows of angular momentum (spin) not accompanied by the electric currents -have opened new horizons for the emerging technologies based on the electron's spin degree of freedom, such as spintronics and magnonics. The main advantage of pure spin current, as compared to the spin-polarized electric current, is the possibility to exert spin transfer torque on the magnetization in thin magnetic films without electrical current flow through the material. In addition to minimizing Joule heating and electromigration effects, this characteristic enables the implementation of spin torque devices based on the low-loss insulating magnetic materials, and offers an unprecedented geometric flexibility. Here we review the recent experimental achievements in investigations of magnetization oscillations excited by pure spin currents in different magnetic nanosystems based on metallic and insulating magnetic materials. We discuss the spectral properties of spin-current nano-oscillators, and relate them to the spatial characteristics of the excited dynamic magnetic modes determined by the spatially-resolved measurements. We also show that these systems 2 support locking of the oscillations to external microwave signals, as well as their mutual synchronization, and can be used as efficient nanoscale sources of propagating spin waves.

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“…In addition, control of the SW wave vector, which is a necessary ingredient for data processing using SWs is achieved by controlling the speed of the propagating droplet via tuning the strength of the broken symmetry. In contrary to the STT and SOT based devices in which higher currents are required to excite shorter SWs [54,55], using droplet for the same purpose is independent of the dc amplitude injected into the NC. Thus, not only it seems as a more energy efficient way to control the wave vector of the SWs, but it gives an additional degree of freedom to tune them.…”

Section: Comparison To Other Spin Torque Based Spin-wave Emittersmentioning

confidence: 99%

Propagating Magnetic Droplet Solitons as Moveable Nanoscale Spin-Wave Sources with Tunable Direction of Emission

et al. 2020

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Magnetic droplets are strongly nonlinear and localized spin-wave solitons that can be formed in current-driven nanocontacts. Here, we propose a simple way to launch droplets in an inhomogeneous nanoscopic waveguide. We use the drift motion of a droplet and show that in a system with broken translational symmetry, the droplet acquires a linear momentum and propagates. We find that the droplet velocity can be tuned via the strength of the break in symmetry and the size of the nanocontact. In addition, we demonstrate that the launched droplet can propagate up to several micrometers in a realistic system with reasonable damping. Finally, we demonstrate how an annihilating droplet delivers its momentum to a highly nonreciprocal spin-wave burst with a tunable wave vector with nanometer wavelengths. Such a propagating droplet can be used as a moveable spin-wave source in nanoscale magnonic networks. The presented method enables full control of the spin-wave emission direction, which can largely extend the freedom to design integrated magnonic circuits with a single spin-wave source.

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Propagating spin waves excited by spin-transfer torque: A combined electrical and optical study

Cited by 35 publications

References 32 publications

Reduced spin torque nano-oscillator linewidth using He+ irradiation

Reduced spin torque nano-oscillator linewidth using He+ irradiation

Magnetization oscillations and waves driven by pure spin currents

Propagating Magnetic Droplet Solitons as Moveable Nanoscale Spin-Wave Sources with Tunable Direction of Emission

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