Control of damping in perpendicularly magnetized thin films using spin-orbit torques

Saha, Susmita; Flauger, Peter; Abert, Claas; Hrabec, Aleš; Luo, Zhaochu; Scagnoli, V.; Suess, Dieter; Heyderman, Laura J.

doi:10.1103/physrevb.101.224401

Cited by 9 publications

(7 citation statements)

References 35 publications

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“…Magnetization oscillations can be driven by both magnetic field and electric current, while the latter offers more attractive ways to control them locally with better scalability. Crucially, sustained auto-oscillations can be achieved when the intrinsic damping is compensated over an oscillation period by the resulting current-induced torques 15,16 . Importantly for technological applications, such oscillations can be translated to a high frequency electric signal using the giant or tunnel magnetoresistance effect.…”

Section: Main Textmentioning

confidence: 99%

Synchronization of chiral vortex nano-oscillators

Zeng

Luo

Heyderman

et al. 2021

Applied Physics Letters

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The development of spintronic oscillators is driven by their potential applications in radio frequency telecommunication and neuromorphic computing. In this work, we propose a spintronic oscillator based on the chiral coupling in thin magnetic films with patterned anisotropy. With an in-plane magnetized disk imprinted on an out-of-plane magnetized slab, the oscillator takes a polar vortex-like magnetic structure in the disk stabilized by a strong Dzyaloshinskii-Moriya interaction. By means of micromagnetic simulations, we investigate its oscillatory properties under applied spin current and, by placing an ensemble of oscillators in the near vicinity, we demonstrate their synchronization with different resonant frequencies. Finally, we show their potential application in neuromorphic computing using a network with six oscillators.

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Section: Main Textmentioning

confidence: 99%

Synchronization of chiral vortex nano-oscillators

Zeng

Luo

Heyderman

et al. 2021

Applied Physics Letters

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“…On one hand, the dynamical shrinkage/expansion of the vortex texture can be manipulated by perpendicular a. c. Magnetic field [15,16], a. c. Current [17], or spin-orbital torques [17,18]. On the other hand, since the inherent dynamics of magnetic vortex is gyrotropic, self-sustained magnetic oscillation can be obtained via spin transfer torques that compensate the intrinsic magnetic damping, which suggests great potential for applications in spin-torque nano-oscillators [13,14,19,20]. The radio-frequency oscillation gives an electric power output in the pico-watt to nano-watt range [21,22], which can be further enhanced by placing the nano-oscillators in arrays or networks.…”

Section: Introductionmentioning

confidence: 99%

“…The modified dynamics of individual oscillator can in turn influence the synchronization [14], and hence large varieties of synchronization patterns can be obtained when different external stimuli are implemented. Indeed, magnetic field and spin-polarised current have been reported to successfully tune the dynamic properties of magnetic vortex nano-oscillators [19,20,34,35]. Since the oscillation frequency depends on the vortex potential energy, the magnetic anisotropy of the vortex region, which directly influences the magnetic anisotropy energy, can provide a new route to modulating the oscillation dynamics.…”

Section: Introductionmentioning

confidence: 99%

Magnetic anisotropy-controlled vortex nano-oscillator for neuromorphic computing

Cui

Liang

et al. 2022

Front. Phys.

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Chiral magnetic vortex has shown great potential for high-density magnetic storage, modern telecommunication and computation devices, thanks to its topological stability and rich dynamic behaviours. Particularly, the synchronization of magnetic vortex nano-oscillators leads to the emergence of fascinating collective phenomena used for microwave generator and neuromorphic computing. In this work, by means of micromagnetic simulations, we create stable chiral magnetic vortices by exploiting the chiral coupling principle and study the gyrotropic motion of the vortex core under spin-transfer torques. The gyrotropic oscillation frequency can be tuned by injecting spin-polarised current as well as the change of the magnetic anisotropy in the vortex area, resulting from the modification of the vortex confine potential and the size of the vortex core. Two vortex nano-oscillators can be synchronized wherein the synchronization state can be modulated by the spin-polarised current and the magnetic anisotropy. Moreover, we demonstrate that the magnetic anisotropy can modify the synchronization patterns when integrating six vortices into an oscillator network, making it potentially serve as an oscillator-based neural network. Our work provides a new route to constructing a flexible oscillator network for neuromorphic computing hardware.

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“…Spin-orbit torques play an important role in spintronics [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], with numerous applications including electric control and magnetization switching [20][21][22], coherent excitation and amplification of spin waves [23][24][25][26], currentinduced collective dynamics of topological spin textures [27][28][29][30][31], memory and logic devices [32][33][34], and neuromorphic computing [35]. Spin-orbit torque oscillators are of particular interest for many applications [36][37][38][39][40], including damping and antidamping torques [41] and other nontrivial features in high frequency response [42,43].…”

Section: Introductionmentioning

confidence: 99%

Level attraction and exceptional points in a resonant spin-orbit torque system

Proskurin,

Stamps

2020

Preprint

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Level attraction can appear in driven systems where instead of repulsion two modes coalesce in a region separated by two exceptional points. This behavior was proposed for optomechanical and optomagnonic systems, and recently observed for dissipative cavity magnon-polaritons. We demonstrate that such a regime exists in a spin-orbit torque system where a magnetic oscillator is resonantly coupled to an electron reservoir. An instability mechanism necessary for mode attraction can be provided by applying an electric field. The field excites interband transitions between spinorbit split bands leading to an instability of the magnetic oscillator. Two exceptional points then appear in the oscillator energy spectrum and the region of instability. We discuss conditions under which this can occur and estimate the electric field strength necessary for reaching the attraction region for a spin-orbit torque oscillator with Rashba coupling. A proposal for experimental detection is made using magnetic susceptibility measurements.

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Control of damping in perpendicularly magnetized thin films using spin-orbit torques

Cited by 9 publications

References 35 publications

Synchronization of chiral vortex nano-oscillators

Synchronization of chiral vortex nano-oscillators

Magnetic anisotropy-controlled vortex nano-oscillator for neuromorphic computing

Level attraction and exceptional points in a resonant spin-orbit torque system

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