A5085822064- Magnetic properties of thin films
- Physics of Superconductivity and Magnetism
- Magnetic Properties and Applications
- Theoretical and Computational Physics
- Characterization and Applications of Magnetic Nanoparticles
- Computational Physics and Python Applications
- Quantum and electron transport phenomena
- Scientific Computing and Data Management
- Distributed and Parallel Computing Systems
- Magnetic and transport properties of perovskites and related materials
- Particle Accelerators and Free-Electron Lasers
- Advanced X-ray Imaging Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Material Science and Thermodynamics
- Particle Detector Development and Performance
- Metallic Glasses and Amorphous Alloys
- Advanced Data Storage Technologies
- Advanced Condensed Matter Physics
- Teaching and Learning Programming
- Crystal Structures and Properties
- Surface and Thin Film Phenomena
- Crystallography and Radiation Phenomena
- Inorganic Fluorides and Related Compounds
- Hydrocarbon exploration and reservoir analysis
- Magnetic confinement fusion research
Imperial College London
2021-2024
University of Southampton
2015-2023
European X-Ray Free-Electron Laser
2017-2022
Multidisciplinary Digital Publishing Institute (Switzerland)
2019
Southwest University
2019
Université Mustapha Stambouli de Mascara
2019
Chinese Academy of Sciences
2019
Hubei University of Automotive Technology
2019
Rockefeller University
1986
Magnetic skyrmions are hailed as a potential technology for data storage and other processing devices. However, their stability against thermal fluctuations is an open question that must be answered before skyrmion-based devices can designed. In this work, we study paths in the energy landscape via which transition between skyrmion uniform state occur interfacial Dzyaloshinskii-Moriya finite-sized systems. We find three mechanisms system take process of nucleation or destruction identify...
Abstract Magnetic skyrmions have the potential to provide solutions for low-power, high-density data storage and processing. One of major challenges in developing skyrmion-based devices is skyrmions’ magnetic stability confined helimagnetic nanostructures. Through a systematic study equilibrium states, using full three-dimensional micromagnetic model including demagnetisation effects, we demonstrate that skyrmionic textures are lowest energy states thin film nanostructures at zero external...
We show theoretically by numerically solving the Landau-Lifshitz-Gilbert equation with a classical spin model on two-dimensional system that both magnetic skyrmions and skyrmion lattices can be moved microwave fields. The mechanism is enabled breaking axial symmetry of skyrmion, for example through application static in-plane external field. net velocity depends frequency amplitude fields as well strength maximum found where coincides resonance breathing mode skyrmions.
We study domain-wall (DW) motion induced by spin waves (magnons) in the presence of Dzyaloshinskii-Moriya interaction (DMI). The DMI exerts a torque on DW when pass through DW, and this represents linear momentum exchange between wave DW. Unlike angular waves, leads to rotation plane rather than motion. In an effective easy anisotropy, transfer mechanism is significantly more efficient moving
The intense research effort investigating magnetic skyrmions and their applications for spintronics has yielded reports of more exotic objects including the biskyrmion, which consists a bound pair counter-rotating vortices magnetization. Biskyrmions have been identified only from transmission electron microscopy images not observed by other techniques, nor seen in simulations carried out under realistic conditions. Here, quantitative Lorentz microscopy, X-ray holography, micromagnetic are...
Computational micromagnetics has become an essential tool in academia and industry to support fundamental research the design development of devices. Consequently, computational is widely used community, fraction time researchers spend performing studies growing. We focus on reducing this by improving interface between numerical simulation researcher. have designed developed a human-centred environment called Ubermag. With Ubermag, scientists can control existing micromagnetic package, such...
In confined helimagnetic nanostructures, skyrmionic states in the form of incomplete and isolated skyrmion can emerge as ground state absence both external magnetic field magnetocrystalline anisotropy. this work, we study dynamic properties (resonance frequencies corresponding eigenmodes) thin film FeGe disk samples. We employ two different methods finite-element based micromagnetic simulation: eigenvalue ringdown method. The method allows us to identify all resonance eigenmodes that exist...
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. This class materials enables Dzyaloshinskii-Moriya interactions (DMI) which favor stabilization chiral configurations. Recent advances in material engineering have shown that confined geometries it is possible to stabilize skyrmionic at zero...
The nonlinear dynamic behavior of a magnetic skyrmion in circular nanodots was studied numerically by solving the Landau-Lifshitz-Gilbert equation with classical spin model. We show that core reversal can be achieved within nanoseconds using perpendicular oscillating field. Two symmetric switching processes correspond to excitations breathing mode and mixed (combination radial spin-wave mode) are identified. For excitation mode, switches through nucleation new from transient uniform state....
<p class="p1">Fidimag is an open-source scientific code for the study of magnetic materials at nano- or micro-scale using either atomistic finite difference micromagnetic simulations, which are based on solving Landau-Lifshitz-Gilbert equation. In addition, it implements simple procedures calculating energy barriers in magnetisation through variants nudged elastic band method. This computer software has been developed with aim creating a structure that can be readily installed, tested, and...
The Karabo distributed control system has been developed to address the challenging requirements of European X-ray Free Electron Laser facility, including complex and custom-made hardware, high data rates volumes, close integration analysis for processing rapid feedback. is a pluggable, application management forming supervisory acquisition environment as part system. provides integrated monitoring, on allowing feedback based algorithms. Services exist access control, logging, configuration...
A phenomenological equation called Landau-Lifshitz-Baryakhtar (LLBar) equation, which could be viewed as the combination of Landau-Lifshitz (LL) and an extra "exchange damping" term, was derived by Baryakhtar using Onsager's relations. We interpret origin this nonlocal damping linking it to spin current pumping. The LLBar is investigated numerically analytically for wave decay domain wall motion. Our results show that lifetime propagation length short-wavelength magnons in presence much...
Recent studies have demonstrated that skyrmionic states can be the ground state in thin-film FeGe disk nanostructures absence of a stabilising applied magnetic field. In this work, we advance understanding by investigating to what extent stabilisation structures through confinement exists geometries do not match cylindrical symmetry skyrmion—such as squares and triangles. Using simulation, show form for range system sizes both triangular square-shaped 10 nm thickness an We further provide...
We demonstrate that chiral skyrmionic magnetization configurations can be found as the minimum energy state in B20 thin film materials with easy-plane magnetocrystalline anisotropy an applied magnetic field perpendicular to plane. Our observations contradict results from prior analytical work, but are compatible recent experimental investigations. The size of observed skyrmions increase anisotropy. use a full micromagnetic model including demagnetization and three-dimensional geometry find...
Abstract Complex magnetic materials hosting topologically non-trivial particle-like objects such as skyrmions are under intensive research and could fundamentally change the way we store process data. One important class of helimagnetic with Dzyaloshinskii-Moriya interaction. Recently, it was demonstrated that thin nanodisks consisting two layers opposite chirality can host a single stable Bloch point different types at interface between layers. Using micromagnetic simulations show FeGe...
Computer simulations are used widely across the engineering and science disciplines, including in research development of magnetic devices using computational micromagnetics. In this work, we identify review different approaches to configuring simulation runs: (i) re-compilation source code, (ii) use configuration files, (iii) graphical user interface, (iv) embedding specification an existing programming language express problem. We advantages disadvantages discuss their implications on...
Abstract The prediction of magnetic skyrmions being used to change the way we store and process data has led materials with Dzyaloshinskii-Moriya interaction coming into focus intensive research. So far, studies have looked mostly at systems composed single chirality. In a search for potential future spintronic devices, combination different chirality system may represent an important new avenue Using finite element micromagnetic simulations, study FeGe disk two layers We show that...
Understanding the role of Dzyaloshinskii-Moriya interaction (DMI) for formation helimagnetic order, as well emergence skyrmions in magnetic systems that lack inversion symmetry, has found increasing interest due to significant potential novel spin based technologies. Candidate materials host include those belonging B20 group such FeGe, known stabilising Bloch-like skyrmions, interfacial cobalt multilayers or Pd/Fe bilayers on top Ir(111), N\'eel-like and, recently, alloys with a...
Scientists who want to use micromagnetic simulation packages, need learn how express the problem of interest in a “language” such as configuration file, script or GUI-clicks that software understands. This language varies from software. If researchers another package, they new re-express their (unchanged) for next For research-project specific pre- post-processing, scientists often write additional We propose vision unified modeling (UMM) approach with which can once and multiple packages be...
Hybridization and charge transfer at molecule-metal interfaces can alter the magnetic anisotropy of transition metal ferromagnets. Here, authors show that molecule C${}_{60}$ increases energy product cobalt thin films by 520 % low temperature. The outline a mechanism for this effect, dubbed $\ensuremath{\pi}$-anisotropy, which explains hardening as consequence $p$-$d$ hybridization broken interfacial symmetry. It is anticipated may provide route towards rare earth free high-coercivity magnet.
Literate computing has emerged as an important tool for computational studies and open science, with growing folklore of best practices. In this work, we report two case studies-one in magnetism another mathematics-where domain-specific software was exposed to the Jupyter environment. This enables high level control simulations computation, interactive exploration results, batch processing on HPC resources, reproducible workflow documentation notebooks. first study, Ubermag drives existing...
We describe the data analysis structure that is integrated into Karabo framework to support scientific experiments and at European XFEL. The photon science have a range of requirements, including online (i.e. near real-time during actual measurement) offline analysis. supports execution automatic for routine tasks, complex experiment protocols feedback integration instrument control, external applications. carried out using distributed accelerator hardware (such as GPUs) where required...
The advent of X-ray free-electron lasers (XFELs) has revolutionized fundamental science, from atomic to condensed matter physics, chemistry biology, giving researchers access X-rays with unprecedented brightness, coherence and pulse duration. All XFEL facilities built until recently provided pulses at a relatively low repetition rate, limited data statistics. Here, results the first megahertz-repetition-rate scattering experiments Spectroscopy Coherent Scattering (SCS) instrument European...
Developments in gauge field theory the past fourteen years are discussed. The canonical description of electroweak and strong interactions is described including role played by QCD QFD. Salam‐Weinberg reviewed with emphasis on Higgs mass renormalization group analysis. Implications hyper‐color theories Composite models quarks leptons considered hyperfermions as part a subquark multiplet. (AIP)