Asymmetric ground state spin configuration of transverse domain wall on symmetrically notched ferromagnetic nanowires

Djuhana, Dede; Piao, Hong‐Guang; Lee, Sang Hyuk; Kim, Dong Hyun; Ahn, Sung Min; Choe, Sug–Bong

doi:10.1063/1.3459965

Cited by 19 publications

(9 citation statements)

References 24 publications

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“…To realize such a device, reproducible and reliable pinning sites for individual DWs are required. Geometric constrictions are widely used to create local confining potentials that act as pinning sites for individual DWs [4][5][6][7][8][9][10]. As an alternative, the local modification of magnetic properties by ion irradiation is suitable to induce pinning sites [11].…”

mentioning

confidence: 99%

Field- and current-induced domain-wall motion in permalloy nanowires with magnetic soft spots

Vogel

Wintz

Gerhardt

et al. 2011

Applied Physics Letters

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We study field- and current-induced domain-wall motion in permalloy nanowires containing a square-shaped magnetically softened region. Implantation of chromium ions is used to induce pinning sites via a local reduction in the saturation magnetization. Micromagnetic simulations, magnetic transmission soft x-ray microscopy, and electrical measurements are employed to characterize the pinning potential which significantly differs for transverse and vortex walls. Reliable domain-wall depinning from a so-called magnetic soft spot by single current pulses is observed. This demonstrates the suitability of these pinning sites for applications.

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mentioning

confidence: 99%

Field- and current-induced domain-wall motion in permalloy nanowires with magnetic soft spots

Vogel

Wintz

Gerhardt

et al. 2011

Applied Physics Letters

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“…Thus, notches along the edges of the wire have been widely used to trap domain walls. [19][20][21][22][23][24][25][26] We believe that both pinning and scattering sites can be originated from a local modification of the sample magnetic properties. As it has been reported in previous articles, [27][28][29][30][31][32] magnetic impurities, e.g., localized magnetic modifications obtained by ion irradiation or implantation into magnetic thin films and multilayers have been employed to manipulate and control the magnetization dynamics in nanostructured systems.…”

Section: Introductionmentioning

confidence: 91%

Position of the transverse domain wall controlled by magnetic impurities in rectangular magnetic nanowires

Toscano

Ferreira

Leonel

et al. 2014

Journal of Applied Physics

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We have performed numerical simulations to demonstrate that the domain wall movement can be controlled introducing a distribution of magnetic impurities in a nanowire. In particular, we have considered two identical impurities equidistant from the nanowire width axis. Pinning and scattering sites for the domain wall can be defined by magnetic impurities, consisting of a local variation of the exchange constant. The domain wall motion was induced by application of a magnetic field pulse and our results indicate that it is possible to control the domain wall position.

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“…The deeper notches pinned the DW more effectively, and the shallower notches were passed over. To resolve all MW states, future devices will require better control of the lithographic notch size and geometry, which could be achieved by altering the notch shape 26,27 and using varying doses to more precisely pattern the notches. In Supplementary Fig.…”

Section: Electrical Characterization Of Magnetic Synapse Prototypesmentioning

confidence: 99%

Shape-Dependent Multi-Weight Magnetic Artificial Synapses for Neuromorphic Computing

Leonard

Liu

Alamdar

et al. 2022

Preprint

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In neuromorphic computing, artificial synapses provide a multi-weight conductance state that is set based on inputs from neurons, analogous to the brain. Additional properties of the synapse beyond multiple weights can be needed, and can depend on the application, requiring the need for generating different synapse behaviors from the same materials. Here, we measure artificial synapses based on magnetic materials that use a magnetic tunnel junction and a magnetic domain wall. By fabricating lithographic notches in a domain wall track underneath a single magnetic tunnel junction, we achieve 4-5 stable resistance states that can be repeatably controlled electrically using spin orbit torque. We analyze the effect of geometry on the synapse behavior, showing that a trapezoidal device has asymmetric weight updates with high controllability, while a straight device has higher stochasticity, but with stable resistance levels. The device data is input into neuromorphic computing simulators to show the usefulness of application-specific synaptic functions. Implementing an artificial neural network applied on streamed Fashion-MNIST data, we show that the trapezoidal magnetic synapse can be used as a metaplastic function for efficient online learning. Implementing a convolutional neural network for CIFAR-100 image recognition, we show that the straight magnetic synapse achieves near-ideal inference accuracy, due to the stability of its resistance levels. This work shows multi-weight magnetic synapses are a feasible technology for neuromorphic computing and provides design guidelines for emerging artificial synapse technologies.

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Asymmetric ground state spin configuration of transverse domain wall on symmetrically notched ferromagnetic nanowires

Cited by 19 publications

References 24 publications

Field- and current-induced domain-wall motion in permalloy nanowires with magnetic soft spots

Field- and current-induced domain-wall motion in permalloy nanowires with magnetic soft spots

Position of the transverse domain wall controlled by magnetic impurities in rectangular magnetic nanowires

Shape-Dependent Multi-Weight Magnetic Artificial Synapses for Neuromorphic Computing

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