Voltage controlled core reversal of fixed magnetic skyrmions without a magnetic field

Bhattacharya, Dhritiman; Al-Rashid, Mamun; Atulasimha, Jayasimha

doi:10.1038/srep31272

Cited by 46 publications

(31 citation statements)

References 53 publications

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“…For efficient electrical manipulation of magnetic skyrmions, voltage or electric field control of magnetism is a more promising pathway [6,193,209,[299][300][301][302][303]. This aspect -electrical control of topological spin textures, also beautifully illustrates the synergies between two different aspects of modern magnetism.…”

Section: Perspectivesmentioning

confidence: 95%

Skyrmions in magnetic multilayers

et al. 2017

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Symmetry breaking together with strong spin-orbit interaction give rise to many exciting phenomena within condensed matter physics. A recent example is the existence of chiral spin textures, which are observed in magnetic systems lacking inversion symmetry. These chiral spin textures, including domain walls and magnetic skyrmions, are both fundamentally interesting and technologically promising. For example, they can be driven very efficiently by electrical currents, and exhibit many new physical properties determined by their real-space topological characteristics. Depending on the details of the competing interactions, these spin textures exist in different parameter spaces. However, the governing mechanism underlying their physical behaviors remain essentially the same. In this review article, the fundamental topological physics underlying these chiral spin textures, the key factors for materials optimization, and current developments and future challenges will be discussed. In the end, a few promising directions that will advance the development of skyrmion based spintronics will be highlighted.This review article is organized as follows:1. Topological physics of magnetic skyrmions 1.1 Origin of spin topology 1.2 Real space topological physics 1.3 Topological distinction of bubble-like spin textures 2. Interfacial chiral magnetism 2.1 From spin spiral to chiral domain wall 2.2 Physical origin of the chiral interfacial DMI 2.3 Measurement of the interfacial DMI 2.4 Unique advantages of magnetic skyrmions in heterostructures 3. Current developments in thin-film skyrmions 3.1 Writing and deleting a single skyrmion 3.2 Blowing magnetic skyrmion bubbles 3.3 Moving skyrmions in wires 3.4 Magnetic skyrmions in asymmetric trilayers 3.5 Characteristics of topological trivial bubbles 3.6 Hall effect of topological charge -skyrmion Hall effect 3.7 High frequency dynamics of magnetic skyrmion 3.8 Artificial skyrmions stabilized by interlayer coupling in thin films 3.9 Novel spin-resolved imaging techniques 3.9.1 Lorentz transmission electron microscopy 3.9.2 Spin-polarized low energy electron microscopy 3.9.3 Photoemission electron microscopy 4. PerspectivesRecent advancements in nanotechnology resulted in concomitant progress in magnetism, with two developments being particularly influential in nanomagnetic systems: controlling magnets via electric (field/current) excitations [5][6][7][8] and the discovery of topological spin textures [9]. Electric control of magnetism is made possible by utilizing the coupling between electron spin and its orbital motion.

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Section: Perspectivesmentioning

confidence: 95%

Skyrmions in magnetic multilayers

et al. 2017

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“…This local manipulation of perpendicular magnetic anisotropy (PMA), known conveniently as the voltage controlled magnetic anisotropy (VCMA), can lead to anisotropy-driven magnetization rotation [20][21][22] potentially altering the spin textures without current dissipation. In fact, the induced effective magnetic field was shown theoretically to enable efficient skyrmion transfer on the thin-film plane [23][24][25] as well as core reversal in a pillar geometry [26]. The effect of VCMA itself has been studied extensively in both ferromagnetic (FM) and antiferromagnetic (AFM) materials with a large change in the anisotropy field demonstrated in the literature [19,20,[27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Creation and Destruction of Skyrmions via Electrical Modulation of Local Magnetic Anisotropy in Magnetic Thin Films

Semenov

2019

Phys. Rev. Applied

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Formation and dissolution of skyrmions via local modulation of magnetic anisotropy is theoretically explored in ferromagnetic (FM) and antiferromagnetic (AFM) thin-film structures. Using a micromagnetic simulation, the spatial and temporal evolution of spin textures are analyzed while the effect of externally controlled effective magnetic anisotropy is introduced for a finite duration. Simulation results clearly indicate that the Néel-type skyrmions can be excited and destroyed in a FM or an AFM layer in selected parameter windows, enabling deterministic encoding of logical states "1" and "0" in this physical system. The characteristic times for the dynamical responses are much faster in the AFMs, particularly in the creation process. The size of the excitation region can be scaled down to the sub-10 nm range in the radius. The investigation also examines the effect of inhomogeneous in-plane magnetic properties, further elucidating the feasibility in realistic conditions. Considering the low power and locally controlled nature of magnetic anisotropy modulation, this approach is expected to provide a highly efficient means for achieving skyrmion based devices. The AFMs offer a particularly promising opportunity.

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“…Magnetic skyrmions ( Fig. 1 (a)) are topologically protected spiral spin textures [25,26], which can be translated by applying small current [27,28] or reversed (in patterned dots) using a small voltage that controls the magnetic anisotropy [29,30]. Until now, this behavior has been leveraged to propose logic and memory devices based on magnetic skyrmions [31][32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

“…While various schemes mimicking neuron and synapse activities have also been proposed utilizing current induced motion of skyrmions [36][37][38][39], neuromorphic devices based on moving skyrmions could have a large foot print and are dissipative as they use current to move the skyrmions. We previously proposed nanomagnetic memory devices utilizing voltage control of fixed magnetic skyrmions in the free layer of a MTJ structure [29,40,41] that can alleviate these issues. In this paper, we use such a voltage control of a fixed skyrmion based scheme to achieve the functionality of resonate and fire neurons.…”

Section: Introductionmentioning

confidence: 99%

Resonate and fire neuron with fixed magnetic skyrmions

Azam

Bhattacharya

Querlioz

et al. 2018

Journal of Applied Physics

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In the brain, the membrane potential of many neurons oscillates in a subthreshold damped fashion and fire when excited by an input frequency that nearly equals their eigen frequency. In this work, we investigate theoretically the artificial implementation of such "resonate-and-fire" neurons by utilizing the magnetization dynamics of a fixed magnetic skyrmion in the free layer of a magnetic tunnel junction (MTJ). To realize firing of this nanomagnetic implementation of an artificial neuron, we propose to employ voltage control of magnetic anisotropy or voltage generated strain as an input (spike or sinusoidal) signal, which modulates the perpendicular magnetic anisotropy (PMA). This results in continual expansion and shrinking (i.e. breathing) of a skyrmion core that mimics the subthreshold oscillation. Any subsequent input pulse having an interval close to the breathing period or a sinusoidal input close to the eigen frequency drives the magnetization dynamics of the fixed skyrmion in a resonant manner. The time varying electrical resistance of the MTJ layer due to this resonant oscillation of the skyrmion core is used to drive a Complementary Metal Oxide Semiconductor (CMOS) buffer circuit, which produces spike outputs. By rigorous micromagnetic simulation, we investigate the interspike timing dependence and response to different excitatory and inhibitory incoming input pulses. Finally, we show that such resonate and fire neurons have potential application in coupled nanomagnetic oscillator based associative memory arrays.

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Voltage controlled core reversal of fixed magnetic skyrmions without a magnetic field

Cited by 46 publications

References 53 publications

Skyrmions in magnetic multilayers

Skyrmions in magnetic multilayers

Creation and Destruction of Skyrmions via Electrical Modulation of Local Magnetic Anisotropy in Magnetic Thin Films

Resonate and fire neuron with fixed magnetic skyrmions

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