Diode Characteristics in Magnetic Domain Wall Devices via Geometrical Pinning for Neuromorphic Computing

Rahaman, Habibur; Kumar, Dheeraj; Chung, Hong Jing; Maddu, Ramu; Lim, Sze Ter; Jin, Tianli; Piramanayagam, S. N.

doi:10.1021/acsami.2c20905

Cited by 6 publications

(5 citation statements)

References 44 publications

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“…We are exploring complementary concepts to achieve symmetric bidirectional motion without an applied magnetic field. 83 Synaptic Device Investigations. The realization of synaptic functions in DW devices requires multiresistance states.…”

Section: Resultsmentioning

confidence: 99%

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Ultralow Energy Domain Wall Device for Spin-Based Neuromorphic Computing

et al. 2023

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Neuromorphic computing (NC) is gaining wide acceptance as a potential technology to achieve lowpower intelligent devices. To realize NC, researchers investigate various types of synthetic neurons and synaptic devices, such as memristors and spintronic devices. In comparison, spintronics-based neurons and synapses have potentially higher endurance. However, for realizing low-power devices, domain wall (DW) devices that show DW motion at low energies�typically below pJ/bit�are favored. Here, we demonstrate DW motion at current densities as low as 10 6 A/m 2 by engineering the β-W spin−orbit coupling (SOC) material. With our design, we achieve ultralow pinning fields and current density reduction by a factor of 10 4 . The energy required to move the DW by a distance of about 18.6 μm is 0.4 fJ, which translates into the energy consumption of 27 aJ/bit for a bit-length of 1 μm. With a meander DW device configuration, we have established a controlled DW motion for synapse applications and have shown the direction to make ultralow energy spin-based neuromorphic elements.

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Section: Resultsmentioning

confidence: 99%

“…However, the pinning strength of the pinning sites of this kind may not be strong enough to support synaptic functionalities. More recently, Rahaman et al studied the concepts of the pine tree DW devices to pin the DWs at the junction of the two DW device segments 83 and demonstrated the intermediate magnetization states.…”

Section: Resultsmentioning

confidence: 99%

Ultralow Energy Domain Wall Device for Spin-Based Neuromorphic Computing

et al. 2023

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“…Pinning the domain wall for an extended period in a uniform pillar devoid of structural disturbances poses challenges. Fortunately, structures such as those with periodically varying pillar diameter or multilayer films with and without perpendicular magnetic anisotropy layers have been proposed to enable domain wall pinning [18,19,37]. In actually fabricated pillars, unintentionally created defects could act as pinning sites for domain wall motion.…”

Section: Discussionmentioning

confidence: 99%

Single current control of magnetization in vertical high-aspect-ratio nanopillars on in-plane magnetization layers

Honda,

Sonobe

2024

J. Phys. D: Appl. Phys.

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Ferromagnetic pillars standing on a substrate hold promise for use in recording segments of multibit nonvolatile memories. These pillars exhibit high thermal stability in their magnetization owing to the influence of shape and perpendicular magnetic anisotropies. Recent micromagnetic simulations have demonstrated the feasibility of magnetization control in these pillars. Such control was achieved through the spin-transfer torque induced by the current flowing within the pillar and the spin-orbit torque generated by the current flowing through the heavy-metal lead at the bottom of the pillars. However, the presence of two current paths complicates circuit design, posing challenges in device integration. To solve this problem, we propose a new structure wherein a pillar is placed on a thin film with in-plane magnetization. When current flows through this structure, a torque is applied to the magnetization of the pillar, similar to that of the three-terminal structure. Magnetization reversal and control in the proposed structure were demonstrated using micromagnetic simulations. Specifically, magnetization reversal was achieved in a 100 nm-long permalloy pillar, whereas the magnetization corresponding to a three-bit sequence was generated in a 250 nm-long permalloy pillar. We propose two methods to control the magnetization of multibit memory. One method uses two different current intensities, whereas the other uses constant and pulsed currents of identical intensity. Notably, in the proposed structure, magnetization was controlled using only a unidirectional current. In particular, magnetization can be controlled with a pulsed current using a single current strength. This advancement will simplify the circuitry required to control magnetic memory, bringing the realization of magnetic memory devices closer to reality.

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“…In another recent study, Rahaman et al investigated pine-tree-shaped DW devices for achieving the synaptic functionalities by exploiting Laplace force on elastic DWs. [52] Multiple magnetization states have been demonstrated by moving the DW along the device via SOT. Cai et al demonstrated multilevel resistance states by pinning the DW at different positions defined by the width changes of the structure.…”

Section: Magnetic Dw Devicesmentioning

confidence: 99%

Spintronic Heterostructures for Artificial Intelligence: A Materials Perspective

Maddu

Kumar

Bhatti

et al. 2023

Physica Rapid Research Ltrs

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With the advent of the Big Data era, neuromorphic computing (NC) (also known as brain‐inspired computing) has gained a lot of research interest. Spintronic devices are the emerging candidates for implementing the NC due to their intrinsic nonvolatility, extremely high endurance, low‐power consumption, and complementary metal‐oxide compatibility. Many research groups have proposed various NC architectures based on spintronic devices. Herein, a collective survey of different spintronic‐based approaches is given for NC. The reviewed approaches include the progress of stochastic magnetic tunnel junction (MTJ) devices, spin‐torque nano‐oscillator, spin‐Hall nano‐oscillator, domain walls, and skyrmion devices. In all of these approaches, spin–orbit torque (SOT)‐based magnetization control, which is achieved via spintronics heterostructures, plays a significant role. Various heterostructures of heavy metal and ferromagnetic layers that have been proposed are reviewed for generating SOT. In addition, the phenomena and materials involved in the generation of orbital torque are summarized due to the orbital Hall effect (OHE), which has recently gained researchers’ attention. Finally, an outlook on the opportunities and challenges for spintronic‐based NC hardware is provided, shedding light on its great potential for artificial intelligence (AI) applications.

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Diode Characteristics in Magnetic Domain Wall Devices via Geometrical Pinning for Neuromorphic Computing

Cited by 6 publications

References 44 publications

Ultralow Energy Domain Wall Device for Spin-Based Neuromorphic Computing

Ultralow Energy Domain Wall Device for Spin-Based Neuromorphic Computing

Single current control of magnetization in vertical high-aspect-ratio nanopillars on in-plane magnetization layers

Spintronic Heterostructures for Artificial Intelligence: A Materials Perspective

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