Inversion of the domain wall propagation in synthetic ferrimagnets

Hamadeh, A.; Pirro, Philipp; Adam, Jean-Paul; Lü, Yuan; Hehn, M.; Petit-Watelot, Sébastien; Mangin, Stéphane

doi:10.1063/1.4993604

Cited by 9 publications

(8 citation statements)

References 18 publications

(20 reference statements)

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“…The rich physics and the applications enabled by interlayer coupling effects in magnetic heterostructures are highly attractive for research purposes. However, with few exceptions [21,22,[36][37][38][39][40][41][42], the majority of such effects have been so far explored in uniformly magnetized layers.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric depinning of chiral domain walls in ferromagnetic trilayers

et al. 2020

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We show that the coupling between two ferromagnetic layers separated by a nonmagnetic spacer can be used to control the depinning of domain walls and induce unidirectional domain wall propagation. We investigated CoFeB/Ti/CoFeB trilayers where the easy axis of the magnetization of the top CoFeB layer is out-of-plane and that of the bottom layer is in-plane. Using Magneto-optic Kerr effect microscopy, we find that the depinning of a domain wall in the perpendicularly magnetized CoFeB layer is influenced by the orientation of the magnetization of the in-plane layer, which gives rise to a field-driven asymmetric domain expansion. This effect occurs due to the magnetic coupling between the internal magnetization of the domain wall and the magnetization of the in-plane CoFeB layer, which breaks the symmetry of updown and down-up homochiral Néel domain walls in the perpendicular CoFeB layer. Micromagnetic simulations support these findings by showing that the interlayer coupling either opposes or favors the Dzyaloshinskii-Moriya interaction in the domain wall, thereby generating an imbalance in the depinning fields. This effect also allows for artificially controlling the chirality and dynamics of domain walls in magnetic layers lacking a strong Dzyaloshinskii-Moriya interaction. I-INTRODUCTION The development of future magnetic memory and logic technologies requires efficient control of magnetization in nanometer-sized devices 1. In a ferromagnet (FM), information can be encoded in magnetic domains and manipulated by displacing them 2,3. A variety of device concepts based on domain wall (DW) motion has been proposed for memory and logic operations 4-6. Many of these proposals rely on unidirectional DW motion along a racetrack, which can be easily achieved by current-induced spin-torques 7-16 , rather than externally applied magnetic fields 3 .

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Section: Introductionmentioning

confidence: 99%

Asymmetric depinning of chiral domain walls in ferromagnetic trilayers

et al. 2020

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“…[5][6][7], as well as the multilayered tracks used in Refs. [14][15][16][17]. Thus in many cases the individual layers may be simulated using 2D transforms, which further results in significant speedup compared to supermesh convolution, the latter requiring a large 3D convolution.…”

Section: Multilayered Convolutionmentioning

confidence: 99%

“…To give examples we distinguish two cases: i) magnetic multilayers with thickness values large compared to the separation between, and ii) ultrathin magnetic multilayers with relatively large separation between the layers. Case i) includes synthetic anti-ferromagnetic structures [14][15][16][17], whilst case ii) occurs most notably in ultrathin magnetic multilayered stacks used to study skyrmions [5][6][7][8]34]. With this method, the local and short-range effective field contributions, e.g.…”

Section: Multilayered Convolutionmentioning

confidence: 99%

“…Racetrack memory devices have also been proposed [11], based on current-induced domain wall motion in multilayered stacks [12,13]. Moreover, magnetic multilayers with surface exchange coupling allow the modification of dipolar interactions in synthetic antiferromagnetic and synthetic ferrimagnetic tracks [14][15][16][17], resulting in fast domain wall motion and reduced threshold currents.…”

Section: Introductionmentioning

confidence: 99%

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Efficient computation of demagnetizing fields for magnetic multilayers using multilayered convolution

Lepadatu

2019

Journal of Applied Physics

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As research into magnetic thin films and spintronics devices is moving from single to multiple magnetic layers, there is a need for micromagnetics modelling tools specifically designed to efficiently handle magnetic multilayers. Here we show an exact method of computing demagnetising fields in magnetic multilayers, which is able to handle layers with arbitrary spacing, arbitrary thicknesses, and arbitrary relative positioning between them without impacting on the computational performance. The multilayered convolution method is a generalisation of the well-known fast Fourier transform-based convolution method used to compute demagnetising fields in a single magnetic body. In typical use cases, such as multilayered stacks used to study skyrmions, we show the multilayered convolution method can be up to 8 times faster, implemented both for central processors and graphics processors, compared to the simple convolution method.

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“…Antiferromagnetic (AFM) materials have been revived as an alternative candidate to their ferromagnetic (FM) counterparts for fast magnetic domain wall switching driven by spin-polarized currents. − However, the nucleation of domain walls in AFM remains very challenging, involving approaches that need vertical spin-polarized current injection in AFM discs or nanowires. − Such a mechanism is tricky to implement because of the difficulty in electrically detecting magnetization reversal in such structures. Ferrimagnetic materials that exhibit antiparallel aligned magnetic sublattices appear as an exchange coupled system with intrinsic properties that are dependent on temperature, composition, and thickness, thus offering a new route to overcome limitations and variability on the domain wall and skyrmions motion. − The manipulation of physical properties in ferrimagnetic heterostructures including perpendicular magnetic anisotropy (PMA), saturation magnetization ( M s ), and compensation temperature ( T M ) , has allowed great advances in increasing the domain wall velocity in thin films and nanowires, − which is desirable for stable functional performance in magnetic memory applications …”

Section: Introductionmentioning

confidence: 99%

Evolution of Zero-Field Ferrimagnetic Domains and Skyrmions in Exchange-Coupled Pt/CoGd/Pt Confined Nanostructures: Implications for Antiferromagnetic Devices

Brandão

Dugato

Santos

et al. 2019

ACS Appl. Nano Mater.

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Magnetic skyrmions are small-sized spin textures with nontrivial topology that behave like charged particles under a spin-polarized current. The efficient use of skyrmions on the next generation of technological devices will depend on the controllable creation of sub-100 nm skyrmions, ideally without any external field. We report on the magnetic domains and skyrmions evolution in nanostructured ferrimagnetic Pt/CoGd/Pt multilayers discs at zero magnetic field and room temperature. The tuning of the magnetic structures is studied as a function of the disc size. The ferrimagnetic labyrinthine stripes are succeeded by the formation of multiple or single isolated ferrimagnetic skyrmions depending on the diameter of the disc. Multiple ferrimagnetic skyrmions present an average size of ∼120 nm, whereas single skyrmions ∼70 nm. It indicates a strong effect played by the confinement of the disc in modifying the skyrmions density and size. Our results shed light on the single ferrimagnetic skyrmion stability at zero magnetic field, which is a further drive in the realization of antiferromagnetic spintronic devices such as skyrmion-based spin torque nano-oscillators with implications in neuromorphic computing.

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Inversion of the domain wall propagation in synthetic ferrimagnets

Cited by 9 publications

References 18 publications

Asymmetric depinning of chiral domain walls in ferromagnetic trilayers

Asymmetric depinning of chiral domain walls in ferromagnetic trilayers

Efficient computation of demagnetizing fields for magnetic multilayers using multilayered convolution

Evolution of Zero-Field Ferrimagnetic Domains and Skyrmions in Exchange-Coupled Pt/CoGd/Pt Confined Nanostructures: Implications for Antiferromagnetic Devices

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