Skyrmion states in thin confined polygonal nanostructures

Pepper, Ryan A.; Beg, Marijan; Cortés‐Ortuño, David; Kluyver, Thomas; Bisotti, Marc Antonio; Carey, R.; Vousden, Mark; Albert, Maximilian; Wang, Weiwei; Hovorka, Ondřej; Fangohr, Hans

doi:10.1063/1.5022567

Cited by 28 publications

(30 citation statements)

References 42 publications

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“…The optimal arrangement of skyrmions fitting within an island clearly follows a close packing ordering of congruent circles, as has been discussed in Ref. 49 for the case of disks, and the system size affects the number of confined skyrmions, 13,16,29,49 which can be characterized by the total topological charge. Furthermore, the shape of the magnetic structures usually become distorted at the phase boundaries, in particular skyrmions, which appear as worm domains.…”

Section: B Phase Diagrammentioning

confidence: 72%

Nanoscale magnetic skyrmions and target states in confined geometries

Cortés‐Ortuño

Romming²,

Beg

et al. 2019

Phys. Rev. B

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Research on magnetic systems with broken inversion symmetry has been stimulated by the experimental proof of particle-like configurations known as skyrmions, whose non-trivial topological properties make them ideal candidates for spintronic technology. In this class of materials, Dzyaloshinskii-Moriya interactions (DMI) are present, which favor the stabilization of chiral configurations. Recent advances in material engineering have shown that in confined geometries it is possible to stabilize skyrmionic configurations at zero field. Moreover, it has been shown that in systems based on Pd/Fe bilayers on top of Ir(111) surfaces skyrmions can be as small as a few nanometres in diameter. In this work we present scanning tunneling microscopy measurements of small Pd/Fe and Pd2/Fe islands on Ir(111) that exhibit a variety of different spin textures, which can be reproduced using discrete spin simulations. These configurations include skyrmions and skyrmion-like states with extra spin rotations such as the target state, which have been of interest due to their promising dynamic properties. Furthermore, using simulations we analyze the stability of these skyrmionic textures as a function of island size, applied field and boundary conditions of the system. An understanding of the parameters and conditions affecting the stability of these magnetic structures in confined geometries is crucial for the development of energetically efficient and optimally sized skyrmion-based devices.

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Section: B Phase Diagrammentioning

confidence: 72%

Nanoscale magnetic skyrmions and target states in confined geometries

Cortés‐Ortuño

Romming²,

Beg

et al. 2019

Phys. Rev. B

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“…We observe that for both states, vortex-like configurations with clear chiralities and polarisations emerge in individual layers. In the literature, the vortex-like states formed as a consequence of DM energy are also called quasi-ferromagnetic 12 , edged vortex 13 , or incomplete skyrmion 10,14,15 states. In both states we identified, the polarisation and the handedness of the vortex-like states in bottom layers are the same and related by the right hand rule - characteristic for the negative DM energy constant.…”

Section: Resultsmentioning

confidence: 99%

Stable and manipulable Bloch point

Beg

Pepper

Cortés‐Ortuño

et al. 2019

Sci Rep

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The prediction of magnetic skyrmions being used to change the way we store and process data has led to materials with Dzyaloshinskii-Moriya interaction coming into the focus of intensive research. So far, studies have looked mostly at magnetic systems composed of materials with single chirality. In a search for potential future spintronic devices, combination of materials with different chirality into a single system may represent an important new avenue for research. Using finite element micromagnetic simulations, we study an FeGe disk with two layers of different chirality. We show that for particular thicknesses of layers, a stable Bloch point emerges at the interface between two layers. In addition, we demonstrate that the system undergoes hysteretic behaviour and that two different types of Bloch point exist. These ‘head-to-head’ and ‘tail-to-tail’ Bloch point configurations can, with the application of an external magnetic field, be switched between. Finally, by investigating the time evolution of the magnetisation field, we reveal the creation mechanism of the Bloch point. Our results introduce a stable and manipulable Bloch point to the collection of particle-like state candidates for the development of future spintronic devices.

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“…They have been predicted theoretically by Bogdanov et al [3], [4] long before their experimental detection and discovery [26,24]. In recent years magnetic skyrmions have attracted a lot of theoretical [13,22,23,39,5,21], simulation [9,18,40,32], and experimental [13,34,17,11,27] attention due to their thermodynamic and topological stability, their small size, and their inherent property of easy movement and repositioning under the application of low or even tiny in-plane electric currents. They seem promising for use in next generation spintronic devices [33,50] as information carriers, giving the credentials of ultra dense low-cost power storage and the capability to perform logical operations [12].…”

Section: Introductionmentioning

confidence: 99%

Micromagnetic simulations study of skyrmions in magnetic FePt nanoelements

Gergidis

Stavrou

Kourounis³

et al. 2019

Journal of Magnetism and Magnetic Materials

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The magnetization reversal in 330nm triangular prismatic magnetic nanoelements with variable magnetocrystalline anisotropy similar to that of partially chemically ordered FePt is studied using micromagnetic simulations employing Finite Element discretizations. Several magnetic properties including the evaluation of the magnetic skyrmion number S are computed in order to characterize magnetic configurations exhibiting vortex-like formations. Magnetic vortices and skyrmions are revealed in different systems generated by the variation of the magnitude and relative orientation of the magnetocrystalline anisotropy direction, with respect to the normal to the triangular prism base. Micromagnetic configurations with skyrmion number greater than one have been detected for the case where magnetocrystalline anisotropy was normal to nanoelement's base. For particular magnetocrystalline anisotropy values three distinct skyrmions are formed and persist for a range of external fields. The simulation-based calculations of the skyrmion number S revealed that skyrmions can be created for magnetic nanoparticle systems lacking of chiral interactions such as Dzyaloshinsky-Moriya, but by only varying the magnetocrystalline anisotropy. arXiv:1810.00253v1 [physics.comp-ph]

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Skyrmion states in thin confined polygonal nanostructures

Cited by 28 publications

References 42 publications

Nanoscale magnetic skyrmions and target states in confined geometries

Nanoscale magnetic skyrmions and target states in confined geometries

Stable and manipulable Bloch point

Micromagnetic simulations study of skyrmions in magnetic FePt nanoelements

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