Micromagnetic modeling of magnetic domain walls and domains in cylindrical nanowires

Fernández-Roldán, José Ángel; Ivanov, Yu. F.; Chubykalo‐Fesenko, O.

doi:10.1016/b978-0-08-102832-2.00014-1

Cited by 37 publications

(14 citation statements)

References 58 publications

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“…Despite this issue, several works in literature report 2D topological charge analysis in nanowires as a function of z dimension. 17,41 In order to understand the evolution of the topological charge as a function of the dot thickness, we have calculated the 2D topological charge a function of the dot thickness coordinate in the dot, according to the following equation:…”

Section: Topological Chargementioning

confidence: 99%

“…14,15 In 1D systems as magnetic nanowires, for instance, the curvature and geometrical confinement have proved to stabilize skyrmionics textures with no need of DMI. 16,17 Planar soft magnetic permalloy (Py, NiFe alloy) dots are believed to host magnetic vortices only. 18 However, the shape and curvature may produce additional effects as the theoretically predicted 3D Bloch-type skyrmions in hemispherical or spherical nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

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Half-hedgehog spin textures in sub-100 nm soft magnetic nanodots

et al. 2020

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Section: Topological Chargementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Half-hedgehog spin textures in sub-100 nm soft magnetic nanodots

et al. 2020

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“…In order to determine the magnetization reversal mechanism of the bisegmented diameter modulated FeCo nanowires, we have modelled the hysteresis loop and the magnetization reversal process in an individual bisegmented FeCo nanowire made of two cylindrical segments with 2 microns in total length, and with 100 and 200 nm in diameter for the narrow and wide segments, respectively, via micromagnetic modelling with MuMax3 (mumax 3 , version 3.10, open source software for micromagnetic simulation; DyNaMat group, Ghent University, Ghent, Belgium) [47]. We have considered typical material parameters of realistic experiments and micromagnetic models of nanowires of FeCo alloys [48][49][50]: a saturation polarization of 2 T, exchange stiffness 25 pJ/m, and a cubic centered magnetocrystalline anisotropy with an anisotropy constant of 10 4 Jm −3 . The interpretation of magneto-optical Kerr effect experiments is carried out from the evaluation of the average magnetization in a region of 400 nm × 400 nm size area and 50 nm in depth over the curved surface of the nanowire, in agreement with the typical order of magnitude for the laser penetration depth in the MOKE technique.…”

Section: Micromagnetic Simulations Of Magnetization Reversalmentioning

confidence: 99%

“…A closer inspection of the magnetic configuration in the nanowire displayed in Figure 6b (1) suggests that the magnetization reversal begins with the nucleation of a pair of vortex structures with opposite chirality along the whole length of the wide segment. These vortex structures consist of a core wherein the magnetization is aligned parallel to the nanowire axis (displayed in red color) and a shell wherein the magnetization rotates around the core (also called vortex tubes [23,49,50]). Such vortex structures have been experimentally reported in X-ray magnetic circular dichroism images in wires with notches [35,53] and predicted in wires with periodical modulations in diameter [50].…”

Section: Micromagnetic Modelling Of the Reversal Process And Moke Modelmentioning

confidence: 99%

Narrow Segment Driven Multistep Magnetization Reversal Process in Sharp Diameter Modulated Fe67Co33 Nanowires

et al. 2021

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Magnetic nanomaterials are of great interest due to their potential use in data storage, biotechnology, or spintronic based devices, among others. The control of magnetism at such scale entails complexing the nanostructures by tuning their composition, shape, sizes, or even several of these properties at the same time, in order to search for new phenomena or optimize their performance. An interesting pathway to affect the dynamics of the magnetization reversal in ferromagnetic nanostructures is to introduce geometrical modulations to act as nucleation or pinning centers for the magnetic domain walls. Considering the case of 3D magnetic nanowires, the modulation of the diameter across their length can produce such effect as long as the segment diameter transition is sharp enough. In this work, diameter modulated Fe67Co33 ferromagnetic nanowires have been grown into the prepatterned diameter modulated nanopores of anodized Al2O3 membranes. Their morphological and compositional characterization was carried out by electron-based microscopy, while their magnetic behavior has been measured on both the nanowire array as well as for individual bisegmented nanowires after being released from the alumina template. The magnetic hysteresis loops, together with the evaluation of First Order Reversal Curve diagrams, point out that the magnetization reversal of the bisegmented FeCo nanowires is carried out in two steps. These two stages are interpreted by micromagnetic modeling, where a shell of the wide segment reverses its magnetization first, followed by the reversal of its core together with the narrow segment of the nanowire at once.

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“…However, despite the significant advantages of racetrack memories, like the increment in the information density or the high reading speed, this potential new storage device still has some limitations that prevent its implementation. Two of the main challenges that are under study are the need to avoid the Walker breakdown to increase the DW velocity [7,8], and the unwanted local Joule heating created at the notches when applying a current pulse through the wire to move the information pattern [9,10].…”

Section: Introductionmentioning

confidence: 99%

A Novel Design of a 3D Racetrack Memory Based on Functional Segments in Cylindrical Nanowire Arrays

Rial

Proença

2020

Nanomaterials

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A racetrack memory is a device where the information is stored as magnetic domains (bits) along a nanowire (track). To read and record the information, the bits are moved along the track by current pulses until they reach the reading/writing heads. In particular, 3D racetrack memory devices use arrays of vertically aligned wires (tracks), thus enhancing storage density. In this work, we propose a novel 3D racetrack memory configuration based on functional segments inside cylindrical nanowire arrays. The innovative idea is the integration of the writing element inside the racetrack itself, avoiding the need to implement external writing heads next to the track. The use of selective magnetic segments inside one nanowire allows the creation of writing and storage sections inside the same track, separated by chemical constraints identical to those separating the bits. Using micromagnetic simulations, our study reveals that if the writing section is composed of two segments with different coercivities, one can reverse its magnetization independently from the rest of the memory device by applying an external magnetic field. Spin-polarized current pulses then move the information bits along selected tracks, completing the writing process by pushing the new bit into the storage section of the wire. Finally, we have proven the efficacy of this system inside an array of 7 nanowires, opening the possibility to use this configuration in a 3D racetrack memory device composed of an array of thousands of nanowires produced by low-cost and high-yield template-electrodeposition methods.

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Micromagnetic modeling of magnetic domain walls and domains in cylindrical nanowires

Cited by 37 publications

References 58 publications

Half-hedgehog spin textures in sub-100 nm soft magnetic nanodots

Half-hedgehog spin textures in sub-100 nm soft magnetic nanodots

Narrow Segment Driven Multistep Magnetization Reversal Process in Sharp Diameter Modulated Fe67Co33 Nanowires

A Novel Design of a 3D Racetrack Memory Based on Functional Segments in Cylindrical Nanowire Arrays

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