Electrical measurement of magnetic-field-impeded polarity switching of a ferromagnetic vortex core

Sushruth, Manu; Fried, Jasper P.; Anane, A.; Xavier, Stéphane; Deranlot, C.; Kostylev, Mikhail; Cros, Vincent; Metaxas, Peter J.

doi:10.1103/physrevb.94.100402

Cited by 9 publications

(7 citation statements)

References 43 publications

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“…1(b)] were observed in the backward half of the measurement. All these features indicate a regular vortex-nucleation-annihilation process in the disk 20,[29][30][31] , confirming the high quality of our structure.…”

Section: B Results Of DC Measurementssupporting

confidence: 80%

Temperature-Dependent Anisotropic Magnetoresistance and Spin-Torque-Driven Vortex Dynamics in a Single Microdisk

Lendinez,

Polakovic,

Ding

et al. 2020

Preprint

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Spin-orbit-torque-driven dynamics have recently gained interest in the field of magnetism due to the reduced requirement of current densities and an increase in efficiency, as well as the ease of implementation of different devices and materials. From a practical point of view, the low-frequency dynamics below 1 GHz is particularly interesting since dynamics associated with magnetic domains lie in this frequency range. While spin-torque excitation of high-frequency modes has been extensively studied, the intermediate low-frequency dynamics have received less attention, although spin torques could potentially be used for both manipulation of the spin texture, as well as the excitation of dynamics. In this work, we demonstrate that it is possible to drive magnetic vortex dynamics in a single microdisk by spin-Hall torque at varying temperatures, and relate the results to transport properties. We find that the gyrotropic mode of the core couples to the low-frequency microwave signal and produces a measurable voltage. The dynamic measurements are in agreement with magnetic transport measurements and are supported by micromagnetic simulations. Our results open the door for integrating magnetic vortex devices in spintronic applications.

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Section: B Results Of DC Measurementssupporting

confidence: 80%

Temperature-Dependent Anisotropic Magnetoresistance and Spin-Torque-Driven Vortex Dynamics in a Single Microdisk

Lendinez,

Polakovic,

Ding

et al. 2020

Preprint

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“…This confirms the theoretical expectations that there is no significant shift in the resonance frequency with the applied in-plane field, when the field is kept well-below the vortex annihilation field 25 . It is worth mentioning that, as expected, no signal could be detected close to 0 mT, due to symmetry arguments 26 .…”

Section: Acs Applied Materials and Interfacessupporting

confidence: 70%

“…Previous works also demonstrate that it is possible to probe the 2ω signal 37,38 . However, by displacing the vortex with a small in-plane static field, the can be measured 26 as presented here. To improve the signal-to-noise ratio, lock-in detection was adopted with the microwave current being amplitude modulated at a frequency of 223 Hz.…”

Section: Acs Applied Materials and Interfacesmentioning

confidence: 99%

Tunable Magnetic Vortex Dynamics in Ion-Implanted Permalloy Disks

Ramasubramanian

Kákay

Fowley

et al. 2020

ACS Appl. Mater. Interfaces

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Nanoscale, low-phase noise, tunable transmitter-receiver links are key for enabling the progress of wireless communication. We demonstrate that vortex-based spin-torque nano-oscillators, which are intrinsically low-noise devices due to their topologically-protected magnetic structure, can achieve frequency tunability when submitted to local ion implantation. In the experiments presented here, the gyrotropic mode is excited with spin-polarized alternating currents and anisotropic magnetoresistance measurements yield discreet frequencies from a single device. Indeed, chromium-implanted regions of permalloy disks exhibit different saturation magnetisation than neighbouring, non-irradiated areas, and thus different resonance frequency, corresponding to the specific area where the core is gyrating. Our study proves that such devices can be fabricated without the need of further lithographical steps, suggesting ion irradiation can be a viable and costeffective fabrication method for densely-packed networks of oscillators. This material is available free of charge via the Internet at http://pubs.acs.org.

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“…Since they are aligned, we can tune simultaneously the resonators coding for the same synaptic weight with a single write-line. Writelines provide an electrical control of synaptic weights either by changing the state of memristors placed above each spintronic resonator as it was done in [47] or in [48], or by switching the magnetization of spintronic resonators between two states [49][50][51][52][53][54] such as in binary neural networks [55][56][57][58][59]. Independently of the control method, a physical implementation of a network with the proposed architecture can be trained with a number of field-lines that does not scale with the number of devices, but only with the number of synaptic weights per filter.…”

Section: Fully-parallel Architecture For Radio-frequency Convolutionsmentioning

confidence: 99%

Convolutional neural networks with radio-frequency spintronic nano-devices

Leroux

Riz

Sanz-Hernández

et al. 2022

Neuromorph. Comput. Eng.

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Convolutional neural networks [1,2] are state-of-the-art and ubiquitous in modern signal processing and machine vision. Nowadays, hardware solutions based on emerging nanodevices are designed to reduce the power consumption of these networks. This is done either by using devices that implement convolutional filters and sequentially multiply consecutive subsets of the input, or by using different sets of devices to perform the different multiplications in parallel to avoid storing intermediate computational steps in memory. Spintronics devices are promising for information processing because of the various neural and synaptic functionalities they offer. However, due to their low OFF/ON ratio, performing all the multiplications required for convolutions in a single step with a crossbar array of spintronic memories would cause sneak-path currents. Here we present an architecture where synaptic communications are based on a resonance effect. These synaptic communications thus have a frequency selectivity that prevents crosstalk caused by sneak-path currents. We first demonstrate how a chain of spintronic resonators can function as synapses and make convolutions by sequentially rectifying radio-frequency signals encoding consecutive sets of inputs. We show that a parallel implementation is possible with multiple chains of spintronic resonators. We propose two different spatial arrangements for these chains. For each of them, we explain how to tune many artificial synapses simultaneously, exploiting the synaptic weight sharing specific to convolutions. We show how information can be transmitted between convolutional layers by using spintronic oscillators as artificial microwave neurons. Finally, we simulate a network of these radio-frequency resonators and spintronic oscillators to solve the MNIST handwritten digits dataset, and obtain results comparable to software convolutional neural networks. Since it can run convolutional neural networks fully in parallel in a single step with nano devices, the architecture proposed in this paper is promising for embedded applications requiring machine vision, such as autonomous driving.

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Electrical measurement of magnetic-field-impeded polarity switching of a ferromagnetic vortex core

Cited by 9 publications

References 43 publications

Temperature-Dependent Anisotropic Magnetoresistance and Spin-Torque-Driven Vortex Dynamics in a Single Microdisk

Temperature-Dependent Anisotropic Magnetoresistance and Spin-Torque-Driven Vortex Dynamics in a Single Microdisk

Tunable Magnetic Vortex Dynamics in Ion-Implanted Permalloy Disks

Convolutional neural networks with radio-frequency spintronic nano-devices

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