scholarly journals Visualizing the strongly reshaped skyrmion Hall effect in multilayer wire devices

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Anthony K. C. Tan ◽  
Pin Ho ◽  
James Lourembam ◽  
Lisen Huang ◽  
Hang Khume Tan ◽  
...  
Keyword(s):  
Hall Effect ◽  
Topological Charge ◽  
Size Dependence ◽  
Particle Model ◽  
Model Simulations ◽  
Generation Computing ◽  
Magnetic Skyrmions ◽  
Transverse Deflection ◽  
Robust Framework ◽  
Geometric Effects

AbstractMagnetic skyrmions are nanoscale spin textures touted as next-generation computing elements. When subjected to lateral currents, skyrmions move at considerable speeds. Their topological charge results in an additional transverse deflection known as the skyrmion Hall effect (SkHE). While promising, their dynamic phenomenology with current, skyrmion size, geometric effects and disorder remain to be established. Here we report on the ensemble dynamics of individual skyrmions forming dense arrays in Pt/Co/MgO wires by examining over 20,000 instances of motion across currents and fields. The skyrmion speed reaches 24 m/s in the plastic flow regime and is surprisingly robust to positional and size variations. Meanwhile, the SkHE saturates at ∼22∘, is substantially reshaped by the wire edge, and crucially increases weakly with skyrmion size. Particle model simulations suggest that the SkHE size dependence — contrary to analytical predictions — arises from the interplay of intrinsic and pinning-driven effects. These results establish a robust framework to harness SkHE and achieve high-throughput skyrmion motion in wire devices.

scholarly journals Skyrmion ratchet propagation: utilizing the skyrmion Hall effect in AC racetrack storage devices

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Börge Göbel ◽  
Ingrid Mertig
Keyword(s):  
Hall Effect ◽  
Soft Or ◽  
Directed Motion ◽  
Ratchet Mechanism ◽  
Storage Devices ◽  
Unique Effect ◽  
Magnetic Skyrmions ◽  
Memory Applications ◽  
Classical Particles ◽  
Transverse Deflection

AbstractMagnetic skyrmions are whirl-like nano-objects with topological protection. When driven by direct currents, skyrmions move but experience a transverse deflection. This so-called skyrmion Hall effect is often regarded a drawback for memory applications. Herein, we show that this unique effect can also be favorable for spintronic applications: We show that in a racetrack with a broken inversion symmetry, the skyrmion Hall effect allows to translate an alternating current into a directed motion along the track, like in a ratchet. We analyze several modes of the ratchet mechanism and show that it is unique for topological magnetic whirls. We elaborate on the fundamental differences compared to the motion of topologically trivial magnetic objects, as well as classical particles driven by periodic forces. Depending on the exact racetrack geometry, the ratchet mechanism can be soft or strict. In the latter case, the skyrmion propagates close to the efficiency maximum.

scholarly journals Emulating spin transport with nonlinear optics, from high-order skyrmions to the topological Hall effect

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Aviv Karnieli ◽  
Shai Tsesses ◽  
Guy Bartal ◽  
Ady Arie
Keyword(s):  
Photonic Crystals ◽  
Hall Effect ◽  
Optical System ◽  
Crystal Engineering ◽  
Spin Transport ◽  
Research Effort ◽  
Nonlinear Photonic Crystals ◽  
Topological Hall Effect ◽  
Magnetic Skyrmions ◽  
Quantum Optical

AbstractExploring material magnetization led to countless fundamental discoveries and applications, culminating in the field of spintronics. Recently, research effort in this field focused on magnetic skyrmions – topologically robust chiral magnetization textures, capable of storing information and routing spin currents via the topological Hall effect. In this article, we propose an optical system emulating any 2D spin transport phenomena with unprecedented controllability, by employing three-wave mixing in 3D nonlinear photonic crystals. Precise photonic crystal engineering, as well as active all-optical control, enable the realization of effective magnetization textures beyond the limits of thermodynamic stability in current materials. As a proof-of-concept, we theoretically design skyrmionic nonlinear photonic crystals with arbitrary topologies and propose an optical system exhibiting the topological Hall effect. Our work paves the way towards quantum spintronics simulations and novel optoelectronic applications inspired by spintronics, for both classical and quantum optical information processing.

Modeling of aggregation kernels for fluidized beds using discrete particle model simulations

Particuology ◽  
2014 ◽  
Vol 13 ◽  
pp. 134-144 ◽  
Author(s):  
Nageswara Rao Narni ◽  
Mirko Peglow ◽  
Gerald Warnecke ◽  
Jitendra Kumar ◽  
Stefan Heinrich ◽  
...  
Keyword(s):  
Fluidized Beds ◽  
Particle Model ◽  
Discrete Particle ◽  
Model Simulations ◽  
Discrete Particle Model

Magnetic skyrmions without the skyrmion Hall effect in a magnetic nanotrack with perpendicular anisotropy

Nanoscale ◽  
2017 ◽  
Vol 9 (29) ◽  
pp. 10212-10218 ◽  
Author(s):  
Yue Zhang ◽  
Shijiang Luo ◽  
Baiqian Yan ◽  
Jun Ou-Yang ◽  
Xiaofei Yang ◽  
...  
Keyword(s):  
Hall Effect ◽  
Perpendicular Anisotropy ◽  
Magnetic Skyrmions

Anisotropy engineering was exploited to prevent the skyrmion Hall effect that is bad for application in memory.

scholarly journals Interface-driven topological Hall effect in SrRuO3-SrIrO3 bilayer

2016 ◽  
Vol 2 (7) ◽  
pp. e1600304 ◽  
Author(s):  
Jobu Matsuno ◽  
Naoki Ogawa ◽  
Kenji Yasuda ◽  
Fumitaka Kagawa ◽  
Wataru Koshibae ◽  
...  
Keyword(s):  
Electron Transport ◽  
Hall Effect ◽  
Solid Angle ◽  
Oxide Interface ◽  
High Quality ◽  
Dm Interaction ◽  
Promising Tool ◽  
Topological Hall Effect ◽  
Magnetic Skyrmions ◽  
Epitaxial Oxide

Electron transport coupled with magnetism has attracted attention over the years. Among them, recently discovered is topological Hall effect (THE), originating from scalar spin chirality, that is, the solid angle subtended by the spins. THE is found to be a promising tool for probing the Dzyaloshinskii-Moriya (DM) interaction and consequent magnetic skyrmions. This interaction arises from broken inversion symmetry and hence can be artificially introduced at interface; this concept is lately verified in metal multilayers. However, there are few attempts to investigate such DM interaction at interface through electron transport. We clarified how the transport properties couple with interface DM interaction by fabricating the epitaxial oxide interface. We observed THE in epitaxial bilayers consisting of ferromagnetic SrRuO3 and paramagnetic SrIrO3 over a wide region of both temperature and magnetic field. The magnitude of THE rapidly decreases with the thickness of SrRuO3, suggesting that the interface DM interaction plays a significant role. Such interaction is expected to realize a 10-nm-sized Néel-type magnetic skyrmion. The present results established that the high-quality oxide interface enables us to tune the effective DM interaction; this can be a step toward future topological electronics.

scholarly journals Skyrmions in anisotropic magnetic fields: strain and defect driven dynamics

MRS Advances ◽  
2019 ◽  
Vol 4 (11-12) ◽  
pp. 643-650 ◽  
Author(s):  
Richard Brearton ◽  
Maciej W. Olszewski ◽  
Shilei Zhang ◽  
Morten R. Eskildsen ◽  
Charles Reichhardt ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Gradient ◽  
Magnetic Field Gradient ◽  
Particle Model ◽  
Shear Forces ◽  
Magnetic Field Profile ◽  
Peak Broadening ◽  
Diffraction Patterns ◽  
The Stability ◽  
Magnetic Skyrmions

ABSTRACTMagnetic skyrmions are particle-like, topologically protected magnetization entities that are promising candidates for information carriers in racetrack-memory schemes. The transport of skyrmions in a shift-register-like fashion is crucial for their embodiment in practical devices. Recently, we demonstrated experimentally that chiral skyrmions in Cu2OSeO3 can be effectively manipulated by a magnetic field gradient, leading to a collective rotation of the skyrmion lattice with well-defined dynamics in a radial field gradient. Here, we employ a skyrmion particle model to numerically study the effects of resultant shear forces on the structure of the skyrmion lattice. We demonstrate that anisotropic peak broadening in experimentally observed diffraction patterns can be attributed to extended linear regions in the magnetic field profile. We show that topological (5-7) defects emerge to protect the six-fold symmetry of the lattice under the application of local shear forces, further enhancing the stability of proposed magnetic field driven devices.

Physics of Hall-effect thruster by particle model

2012 ◽  
Author(s):  
Francesco Taccogna ◽  
Pierpaolo Minelli ◽  
Mario Capitelli ◽  
Savino Longo
Keyword(s):  
Hall Effect ◽  
Particle Model ◽  
Hall Effect Thruster

scholarly journals Magnetic Skyrmion Generation by Reflective Spin Wave Focusing

2021 ◽  
Vol 9 ◽  
Author(s):  
Xianglong Yao ◽  
Zhenyu Wang ◽  
Menghua Deng ◽  
Z.-X. Li ◽  
Zhizhi Zhang ◽  
...  
Keyword(s):  
Topological Charge ◽  
Path Length ◽  
Focal Point ◽  
Spin Waves ◽  
Micromagnetic Simulations ◽  
Driving Field ◽  
Spintronic Devices ◽  
Theoretical Design ◽  
Frequency Independent ◽  
Magnetic Skyrmions

We propose a method to generate magnetic skyrmions by focusing spin waves totally reflected by a curved film edge. The edge contour is derived to be parabolic and frequency-independent based on the identical magnonic path length principle. We performed micromagnetic simulations to verify our theoretical design. Under proper conditions, the reflected spin waves first converge at the focal point with the enhanced intensity leading to the emergence of magnetic droplets, which are then converted to magnetic skyrmion accompanied by a change in the topological charge. We numerically obtain the phase diagram of skyrmion generation with respect to the amplitude and frequency of the driving field. Our finding would be helpful for the design of spintronic devices combining the advantage of skyrmionics and magnonics.

scholarly journals Coexistence of distinct skyrmion phases observed in hybrid ferromagnetic/ferrimagnetic multilayers

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Andrada-Oana Mandru ◽  
Oğuz Yıldırım ◽  
Riccardo Tomasello ◽  
Paul Heistracher ◽  
Marcos Penedo ◽  
...  
Keyword(s):  
Hall Effect ◽  
Low Temperatures ◽  
Room Temperature ◽  
Multilayer System ◽  
Efficient Storage ◽  
A Chain ◽  
Magnetic Skyrmions ◽  
Memory Applications

AbstractMaterials hosting magnetic skyrmions at room temperature could enable compact and energetically-efficient storage such as racetrack memories, where information is coded by the presence/absence of skyrmions forming a moving chain through the device. The skyrmion Hall effect leading to their annihilation at the racetrack edges can be suppressed, for example, by antiferromagnetically-coupled skyrmions. However, avoiding modifications of the inter-skyrmion distances remains challenging. As a solution, a chain of bits could also be encoded by two different solitons, such as a skyrmion and a chiral bobber, with the limitation that it has solely been realized in B20-type materials at low temperatures. Here, we demonstrate that a hybrid ferro/ferri/ferromagnetic multilayer system can host two distinct skyrmion phases at room temperature, namely tubular and partial skyrmions. Furthermore, the tubular skyrmion can be converted into a partial skyrmion. Such systems may serve as a platform for designing memory applications using distinct skyrmion types.

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