Direct Observation of Massless Domain Wall Dynamics in Nanostripes with Perpendicular Magnetic Anisotropy

Vogel, Jan; Bonfim, Marlio; Rougemaille, Nicolas; Boulle, Olivier; Miron, Ioan Mihai; Auffret, S.; Rodmacq, B.; Gaudin, Gilles; Cezar, J. C.; Sirotti, Fausto; Pizzini, S.

doi:10.1103/physrevlett.108.247202

Cited by 58 publications

(62 citation statements)

References 28 publications

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“…These measurements show that the critical switching current is mostly dependent on the DW mobility and sample dimensions rather than on the initial nucleation barrier. Further, our results agree with the absence of DW inertia reported in Pt/Co layers 44,45 , consistently with the fast damping of magnetic excitations in SOT devices, and show that partial but reliable switching can be obtained also when working below the current amplitude required for full switching.…”

supporting

confidence: 90%

Spatially and time-resolved magnetization dynamics driven by spin–orbit torques

et al. 2017

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Current-induced spin-orbit torques (SOTs) represent one of the most effective ways to manipulate the magnetization in spintronic devices. The orthogonal torquemagnetization geometry, the strong damping, and the large domain wall velocities inherent to materials with strong spin-orbit coupling make SOTs especially appealing for fast switching applications in nonvolatile memory and logic units. So far, however, the timescale and evolution of the magnetization during the switching process have remained undetected. Here, we report the direct observation of SOTdriven magnetization dynamics in Pt/Co/AlO x dots during current pulse injection.Time-resolved x-ray images with 25 nm spatial and 100 ps temporal resolution reveal that switching is achieved within the duration of a sub-ns current pulse by the fast nucleation of an inverted domain at the edge of the dot and propagation of a tilted domain wall across the dot. The nucleation point is deterministic and alternates between the four dot quadrants depending on the sign of the magnetization, current, and external field. Our measurements reveal how the magnetic symmetry is broken by the concerted action of both damping-like and field-like SOT and show that reproducible switching events can be obtained for over 10 12 reversal cycles. arXiv:1704.06402v1 [cond-mat.mtrl-sci] 21 Apr 2017Controlling the magnetic state of ultrathin heterostructures using electric currents is key to developing nonvolatile memory devices with minimal static and dynamic power consumption 1 . A promising approach for magnetic switching is based on injecting an in-plane current into a ferromagnet/heavy metal bilayer, where the spin-orbit torques (SOTs) 2,3 resulting from the spin Hall effect and interface charge-spin conversion 4-8 provide an efficient mechanism to reverse the magnetization 1,9,10,12-15 and manipulate domain walls (DWs) [16][17][18][19] .SOT switching schemes can be easily integrated into three-terminal magnetic tunnel junctions having either in-plane 10 or out-of-plane 20 magnetization. Although the threeterminal geometry is more demanding in terms of size, it offers desirable features compared to the two-terminal spin-transfer torque (STT) approach presently used in magnetic random access memories (MRAM) 21 . One such feature is the separation of the read and write current paths in the tunnel junction, which avoids electrical stress of the oxide barrier during writing and allows for independent optimization of the tunneling magnetoresistance during reading. The other crucial feature is the switching speed, which is expected to be extremely fast because the spin accumulation inducing the SOTs is orthogonal to the quiescent magnetization, leading to a negligible incubation delay. Such a delay is a major issue for STT devices, since thermal fluctuations result in a switching time distribution that is several ns wide 22,23 . Furthermore, the SOT-induced magnetization dynamics is governed by strong damping in the monodomain regime 24,25 and fast domain wall motion in the m...

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confidence: 90%

Spatially and time-resolved magnetization dynamics driven by spin–orbit torques

et al. 2017

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“…Application of device structures based on lateral spin valves [9,11], as well as domain-wall magnets (DWM) [10,12] were proposed. [14,16,17,18]. Thus a spin neuron with 60nm long fee-layer with cross-section area of 20x2 nm 2 may be switched with a current of less than 10µA within 1ns [14,22].…”

Section: Spin Torque Neuronmentioning

confidence: 99%

Spin-neurons: A possible path to energy-efficient neuromorphic computers

Sharad

Fan

Roy

2013

Journal of Applied Physics

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Recent years have witnessed growing interest in the field of brain-inspired computing based on neural-network architectures. In order to translate the related algorithmic models into powerful, yet energy-efficient cognitive-computing hardware, computing-devices beyond CMOS may need to be explored. The suitability of such devices to this field of computing would strongly depend upon how closely their physical characteristics match with the essential computing primitives employed in such models. In this work we discuss the rationale of applying emerging spin-torque devices for bio-inspired computing. Recent spin-torque experiments have shown the path to low-current, low-voltage and high-speed magnetization switching in nano-scale magnetic devices. Such magneto-metallic, current-mode spin-torque switches can mimic the analog summing and 'thresholding' operation of an artificial neuron with high energy-efficiency.Comparison with CMOS-based analog circuit-model of neuron shows that spin neurons can achieve more than two orders of magnitude lower energy and beyond three orders of magnitude reduction in energy-delay product. The application of spin neurons can therefore be an attractive option for neuromorphic computers of future.2

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“…In particular, the acceleration=deceleration behavior triggered a debate on the existence of DW mass. 36,37) From a technological aspect, high-speed DW motion of up to 100 m=s was obtained for a current density of 1.5 × 10 12 A=m 2 , 38) a comparable speed to that of existing hard disk drives (HDDs). Controlled DW motion using multiple current pulses was successfully demonstrated and a proofof-concept experiment for the operation of a 3-bit shift register was also reported.…”

Section: Progress In Study Of Current-induced Domain Wall Motionmentioning

confidence: 99%

Current-driven magnetic domain wall motion and its real-time detection

Kim

Yoshimura

Ono

2017

Jpn. J. Appl. Phys.

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Current-controlled magnetic domain wall motion has opened the possibility of a novel type of shift register memory device, which has been optimistically predicted to replace existing magnetic memories. Owing to this promising prospect, intensive work has been carried out during the last few decades. In this article, we first review the progress in the study of current-induced magnetic domain wall motion. Underlying mechanisms behind the domain wall motion, which have been discovered during last few decades, as well as technological achievements are presented. We then present our recent experimental results on the real-time detection of current-driven multiple magnetic domain wall motion, which directly demonstrates the operation of a magnetic domain wall shift register.

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Direct Observation of Massless Domain Wall Dynamics in Nanostripes with Perpendicular Magnetic Anisotropy

Cited by 58 publications

References 28 publications

Spatially and time-resolved magnetization dynamics driven by spin–orbit torques

Spatially and time-resolved magnetization dynamics driven by spin–orbit torques

Spin-neurons: A possible path to energy-efficient neuromorphic computers

Current-driven magnetic domain wall motion and its real-time detection

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