Yu Li's zone

A postdoc @Fudan Uni, China

Yu Li's zone

Magnetic skyrmions are nanoscale spin textures that their thermal stability originates from the nontrivial topology in nature. Recently, a plethora of topological spin textures have been theoretically predicted or experimentally observed, enriching the diversity of the skyrmionic family. In this work, we theoretically demonstrate the stabilities of various topological spin textures against homochiral states in chiral magnets, including chiral bobbers, dipole strings, and skyrmion tubes ...
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We conducted an in-depth study of the resistance-switching mechanism in classical HfOx-based devices. Through atomic-level characterisation of the dynamic evolution of conductive filaments, we confirmed that the filament system in this type of device has a quasi-core-shell structure, consisting of a metallic Hf6O core and an insulating HfO2 crystalline shell. constitute. The study pinpointed multiple …

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Tailored magnetic multilayers (MMLs) provide skyrmions with enhanced thermal stability, leading to the possibility of skyrmion-based devices for room temperature applications. At the same time, the search for additional stable topological spin textures has been under intense research focus. Besides their fundamental importance, such textures may expand the information encoding capability of spintronic devices. However, fractional spin texture states within MMLs in the vertical dimension have yet to be investigated. In this work, we demonstrate numerically fractional skyrmion tubes (FSTs) in a tailored MML system ...
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The exchange stiffness constant is recognized as one of the fundamental properties of magnetic materials, though its accurate experimental determination remains a particular challenge. In thin films, resonance measurements exploiting perpendicular standing spin waves (PSSWs) are increasingly used to extract this parameter, typically through a determination of the first-order PSSW mode. Here, we present a systematic study of multiple PSSW modes in NiFe films, where both the sample thickness and the cap layer material are varied. The results show that a simple analysis based on the Kittel rigid pinning model yields an exchange stiffness constant that varies with thickness, mode number, and capping layer material ...
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Magnetic skyrmions have been in the spotlight since they were observed in technologically relevant systems at room temperature. More recently, there has been increasing interest in additional quasiparticles that may exist as stable/metastable spin textures in magnets, such as the skyrmionium and the antiskyrmionite (i.e., a skyrmion bag with two skyrmions inside) that have distinct topological characteristics. The next challenge and opportunity, at the same time, is to investigate the use of multiple magnetic quasiparticles as information carriers in a single device for next-generation nanocomputing. In this paper, we propose a spintronic interconnect device where multiple sequences of information signals are encoded and transmitted simultaneously by skyrmions, skyrmioniums, and antiskyrmionites ...
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Magnetic multilayers are promising tunable systems for hosting magnetic skyrmions at/above room temperature. Revealing their intriguing switching mechanisms and associated inherent electrical responses are prerequisites for developing skyrmionic devices. In this Letter, we theoretically demonstrate the annihilation of single skyrmions occurring through a multilayer structure, which is mediated by the hopping dynamics of topological hedgehog singularities ...
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Synthetic ferromagnets (SFMs) possess the same layer structure found in the widely studied synthetic antiferromagnets. This consists of two ferromagnetic (FM) layers separated by a non-magnetic (NM) spacer forming the structure FM1/NM/FM2, but SFMs describe the case where the interlayer exchange coupling promotes the parallel alignment of the magnetizations of the FM layers. The frequency and phase of the dynamic response of these structures depends sensitively on the interlayer exchange coupling as well as on the individual layer magnetizations. Through experiments and numerical simulations, we show that the dynamic response of the two ferromagnetic layers has an orthogonal dependence on the difference in layer magnetization and interlayer coupling allowing both parameters to be determined accurately …

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(Abstract) The topological properties of skyrmionic quasiparticles such as magnetic skyrmions and skyrmioniums enable their applications in future low-power, ultradense nanocomputing and neuromorphic systems. We propose here an all-magnetic skyrmionic interconnect, which has so far been the “missing component.” This interconnect will…

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We developed a surface roughness model for magnetic systems, by taking into account the space-dependent uniaxial anisotropy and Dzyaloshinskii-Moriya interaction (DMI). The spacial variation is determined by the surface topography of multilayer structure, which is characterised by atomic force microscopy. By using micromagnetic technique, we found that the DMI is required for the stabilisation of meron-like spin textures in an in-plane magnetised [Pt/Co/Ta] trilayer structure. Furthermore, with the presence of surface roughness, much larger textures can be stabilised with lateral dimensions from 0.2 to 2 μm, in agreement with experimental observations. Please find more out in our published paper!

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The image is captured during the field-induced magnetic transition of a skyrmion lattice in theory. The colour code indicates the component of magnetisation perpendicular to the film surface. Increasing of the magnetic field forces skyrmion diameter to expand. Then the lattice inversion occurs involving the breaking of domain alls accompained with the emergence of transient antiskyrmions.

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