Chirality-Based Vortex Domain-Wall Logic Gates

Omari, Khalid A.; Hayward, Thomas J.

doi:10.1103/physrevapplied.2.044001

Cited by 70 publications

(70 citation statements)

References 25 publications

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“…3,4 Recently, new schemes have been proposed in which the domain walls themselves represent the data bits. 5 However, domain walls are subject to thermal fluctuations which can compromise the position of the walls, and thus the integrity of the data. Consequently, thermal effects should be taken into account in the design and should first be understood.…”

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confidence: 99%

Thermal effects on transverse domain wall dynamics in magnetic nanowires

Leliaert

Wiele

Vandermeulen

et al. 2015

Applied Physics Letters

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confidence: 99%

Thermal effects on transverse domain wall dynamics in magnetic nanowires

Leliaert

Wiele

Vandermeulen

et al. 2015

Applied Physics Letters

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“…In addition to providing a tool to control VDW chirality in experimental studies this will be useful in chirality-based logic devices 11 where the chiralities of VDWs must be switched as they propagate through complex nanowire networks. Furthermore, corners could be used to "reset" DW chirality to suppress stochastic pinning effects in more conventional devices where data is encoded using the orientation of magnetic domains.…”

mentioning

confidence: 99%

“…10 In systems where DW structure can be stabilized, chirality also offers a binary degree of freedom, leading to proposals for chirality-based logic networks. 11 DWs injected using injection pads or current lines have random chiralities, leading to uncontrolled pinning behaviors. However, by breaking the symmetry of these features, chirality can be controlled at the point of injection.…”

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confidence: 99%

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Ballistic rectification of vortex domain wall chirality at nanowire corners

Omari

Bradley

Broomhall

et al. 2015

Applied Physics Letters

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The interactions of vortex domain walls with corners in planar magnetic nanowires are probed using magnetic soft X-ray transmission microscopy. We show that when the domain walls are propagated into sharp corners using applied magnetic fields above a critical value, their chiralities are rectified to either clockwise or anticlockwise circulation depending on whether the corners turn left or right. Single-shot focused magneto-optic Kerr effect measurements are then used to demonstrate how, when combined with modes of domain propagation that conserve vortex chirality, this allows us to dramatically reduce the stochasticity of domain pinning at artificial defect sites. Our results provide a tool for controlling domain wall chirality and pinning behavior both in further experimental studies and in future domain wall-based memory, logic and sensor technologies. Devices based on the motion of domain walls (DWs) in magnetic nanowires have been in development for over a decade. [1][2][3] While simple descriptions visualize DWs as rigid particles, DWs actually have complex internal magnetization structures 4 that change dynamically as they propagate. [5][6][7] Key to understanding DW structure is the concept of chirality, which describes the sense of magnetization rotation across the DW. For example, in the case of vortex DWs (VDWs), chirality dictates whether their internal magnetization rotates clockwise (CW) or anticlockwise (ACW) around a central out-of-plane core.Chirality has a strong influence on DW behavior: VDWs with opposite chiralities pin differently at notches, resulting in stochastic depinning field distributions in systems where chirality is ill-defined. 8,9 Furthermore, chirality dictates the paths of DWs in branched nanowires, and therefore the geometry of Dirac strings in artificial spin-ice lattices. 10 In systems where DW structure can be stabilized, chirality also offers a binary degree of freedom, leading to proposals for chirality-based logic networks. 11 DWs injected using injection pads or current lines have random chiralities, leading to uncontrolled pinning behaviors. However, by breaking the symmetry of these features, chirality can be controlled at the point of injection. 10,12 Controlling and manipulating chiralities during propagation is more challenging, but can be achieved by interacting DWs with orthogonal nanowire sections, 13 large notches, 14 or enddomains; 15 however, these approaches all involve the introduction of large defects into the nanowires. Pulsed rotating fields can be used to select DW chirality in ring-shaped nanowires, 16 but this approach would be complex to implement in devices.In this paper, we propose a simple method of controlling DW chirality in continuous nanowires. We show that DWs propagated ballistically into sharp nanowire corners are reliably rectified to either CW or ACW chirality depending on whether the corner turns left or right. We then demonstrate how this approach can be exploited to dramatically reduce the stochasticity of pinning at artificial defect...

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“…12 Nevertheless, larger speed and higher density are expected if the signal is directly transmitted through a continuous free layer, as in Domain Wall (DW) logic. [13][14][15][16] Most of these concepts implement the common NAND, NOR or NOT functions, while others 8,9,17 utilize a majority gate. It is known that any arithmetic operation can be synthesized from inverters and three-input majority gates.…”

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confidence: 99%

Toward error-free scaled spin torque majority gates

et al. 2016

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The functionality of a cross-shaped Spin Torque Majority Gate is explored by means of micromagnetic simulations. The different input combinations are simulated varying material parameters, current density and size. The main failure mode is identified: above a critical size, a domain wall can be pinned at the center of the cross, preventing further propagation of the information. By simulating several phase diagrams, the key parameters are obtained and the operating condition is deduced. A simple relation between the domain wall width and the size of the Spin Torque Majority Gate determines the working range. Finally, a correlation is found between the energy landscape and the main failure mode. We demonstrate that a macrospin behavior ensures a reliable majority gate operation.

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Chirality-Based Vortex Domain-Wall Logic Gates

Cited by 70 publications

References 25 publications

Thermal effects on transverse domain wall dynamics in magnetic nanowires

Thermal effects on transverse domain wall dynamics in magnetic nanowires

Ballistic rectification of vortex domain wall chirality at nanowire corners

Toward error-free scaled spin torque majority gates

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