A5087118479- Magnetic properties of thin films
- Theoretical and Computational Physics
- Magnetic Properties and Applications
- Physics of Superconductivity and Magnetism
- Magneto-Optical Properties and Applications
- Advanced Condensed Matter Physics
- Quantum and electron transport phenomena
- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Magnetic and transport properties of perovskites and related materials
- Characterization and Applications of Magnetic Nanoparticles
- Quantum many-body systems
- Multiferroics and related materials
- Magnetic Properties of Alloys
- Mechanical and Optical Resonators
- Surface and Thin Film Phenomena
- Photonic Crystals and Applications
- Magnetic Properties and Synthesis of Ferrites
- Electric Motor Design and Analysis
- Ferroelectric and Piezoelectric Materials
- ZnO doping and properties
- Photonic and Optical Devices
- Plasmonic and Surface Plasmon Research
- Geophysics and Sensor Technology
- Metallic Glasses and Amorphous Alloys
University of Manitoba
2017-2025
University of Glasgow
2011-2020
Conference Board
2017-2018
Alpha Omega Electromagnetics (United States)
2018
Institute of Electrical and Electronics Engineers
2017
University of Leeds
2017
Istituto Officina dei Materiali
2017
The University of Tokyo
2017
Scottish Universities Physics Alliance
2016
The University of Western Australia
2006-2015
Modern applications for thin film magnets involve unique requirements the control and design of specific magnetic properties. The exchange bias effect in ferromagnet/antiferromagnet bilayers appears to be a useful feature controlling one most important characteristics ferromagnet: coercivity. Prospects enhancement desirable effects depend upon clear understanding mechanisms governing bias. processes underlying existence properties are reviewed, with particular emphasis on roles interface...
We demonstrate the functionality of spin-wave logic exclusive-not-OR and not-AND gates based on a Mach-Zehnder-type interferometer which has arms implemented as sections ferrite film waveguides. Logical input signals are applied to by varying either phase or amplitude spin waves in arms. This variation is produced Oersted fields dc current pulses through conductors placed surface magnetic films.
We report on magnetic domain-wall velocity measurements in ultrathin Pt/Co(0.5-0.8 nm)/Pt films with perpendicular anisotropy over a large range of applied fields. The complete velocity-field characteristics are obtained, enabling an examination the transition between thermally activated creep and viscous flow: motion regimes predicted from general theories for driven elastic interfaces weakly disordered media. dissipation limited flow regime is found to be consistent precessional motion,...
We report dissipative magnon-photon coupling caused by cavity Lenz effect, where the magnons in a magnet induce rf current cavity, leading to back action that impedes magnetization dynamics. This effect is revealed our experiment as level attraction with coalescence of hybridized modes, which distinctly different from repulsion mode anticrossing coherent coupling. develop method control in- terpolation and coupling, observe matching condition two effects cancel. Our work sheds light on...
Magnetism is a very fascinating and dynamic field. Especially in the last 30 years, there have been many major advances range of areas from novel fundamental phenomena to new products. Applications such as hard disc drives magnetic sensors are part our daily life applications, non-volatile computer random access memory, expected surface shortly. Thus it an opportune time for describing current status future challenges form roadmap article. The 2014 Roadmap provides view on several selected,...
Lithographic processing and film growth technologies are continuing to advance, so that it is now possible create patterned ferroic materials consisting of arrays sub-1 μm elements with high definition. Some the most fascinating behaviour these can be realised by exploiting interactions between individual new functionality. The properties artificial systems differ strikingly from those their constituent components, novel emergent arising collective dynamics interacting elements, which...
The authors discuss some of the fundamental properties unique to magnetic multilayers. Complex spin configurations are examined for many different systems and shown arise from a simple competition between exchange Zeeman energies. found in multilayer determine macroscopic such as static susceptibility magnetization, can lead anomalous field temperature behaviour. also dynamic behavior Emphasis is placed on waves multilayers with canted softening modes at phase transitions. Furthermore they...
We present experimental evidence that ferromagnetic order at room temperature in ultrathin epitaxial Co(001) layers on Cu(001) substrates is stabilized by in-plane magnetic anisotropies. All relevant anisotropy contributions have been determined as a function of Co layer thickness with and without an additional Cu overlayer.
Transmission of microwave spin waves through a microstructured magnonic crystal in the form permalloy waveguide periodically varying width was studied experimentally and theoretically. The wave characteristics were measured by spatially-resolved Brillouin light scattering microscopy. A rejection frequency band clearly observed. gap controlled applied magnetic field. spin-wave intensity as function propagation distance is good agreement with model calculation.
The channeling of spin waves with domain walls in ultrathin ferromagnetic films is demonstrated theoretically and through micromagnetics simulations. It shown that propagating excitations localized to the wall, which appear frequency gap bulk wave modes, can be guided curved geometries propagate close proximity other channels. For Néel-type arising from a Dzyaloshinskii-Moriya interaction, strongly nonreciprocal group velocities exceed 1 km/s long wavelength limit for certain propagation...
Theoretical analysis and Lorentz transmission electron microscopy (LTEM) investigations in an FeGe wedge demonstrate that chiral twists arising near the surfaces of noncentrosymmetric ferromagnets [Meynell et al., Phys. Rev. B 90, 014406 (2014)] provide a stabilization mechanism for magnetic Skyrmion lattices helicoids cubic helimagnet nanolayers. The phase diagram obtained freestanding nanolayers shows magnetization processes differ fundamentally from those bulk helimagnets are...
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...
Understanding the conditions determining appearance of stable chiral spin topological excitations is a central problem in condensed matter physics and related fields. This work provides first unambiguous demonstration discretization due to macroscopic phase coherence metastability for excitations, evidence mechanisms underlying its appearance. was achieved through use an advanced Lorentz electron microscope with highest possible resolution imaging textures. The results provide new insights...
Ultrathin metallic ferromagnets on substrates with strong spin-orbit coupling can exhibit induced chiral interactions of the Dzyaloshinskii-Moriya (DM) form. For systems perpendicular anisotropy, presence DM has important consequences for current-driven domain-wall motion and underpins possible spintronic applications involving skyrmions. We show theoretically how spin textures driven by interaction allow nonreciprocal channeling waves, leading to measurable features in magnetic wires, dots,...
By using the stripline Microwave Vector–Network Analyser Ferromagnetic Resonance and Time Domain spectroscopy techniques, we study a strong coupling regime of magnons to microwave photons in planar geometry lithographically formed split-ring resonator (SRR) loaded by single-crystal epitaxial yttrium–iron–garnet (YIG) film. Strong anti-crossing photon modes SRR magnon YIG film is observed applied-magnetic-field resolved measurements. The strength extracted from experimental data reaches 9% at...
Results of the switching properties Stoner-like magnetic particles, subject to short field pulses, obtained by numerical investigations, are reported. The discussed as a function external pulse strength and direction, length, shape. For pulses long compared precession time, behavior is governed damping term. In limit dominated details precession. latter case, term minor importance ultrafast can be achieved choosing right parameters. It also possible choose parameters in order provide over...
Collective spin wave modes propagating in an array of magnetic stripes coupled by dynamic dipole interaction are investigated Brillouin light scattering. It is demonstrated that this structure supports propagation discrete waves at any angle with respect to the length. The data interpreted using a theoretical model based on Bloch approach. shown that, due one-dimensional artificial periodicity medium, gaps spectrum partial: frequency passbands for along direction overlap stop bands stripes.
Quenched disorder affects how nonequilibrium systems respond to driving. In the context of artificial spin ice, an athermal system comprised geometrically frustrated classical Ising spins with a twofold degenerate ground state, we give experimental and numerical evidence such washes out edge effects provide estimate strength in system. We prove analytically that sequence applied fields fixed amplitude is unable drive its state from saturated state. These results should be relevant for other...
Artificial square ices are structures composed of magnetic nanoelements arranged on the sites a two-dimensional lattice, such that there four interacting elements at each vertex, leading to geometrical frustration. Using semianalytical approach, we show exhibit rich spin-wave band structure is tunable both by external fields and magnetization configuration individual elements. Internal degrees freedom can give rise equilibrium states with bent element edges characteristic excitations; in...
Magnetic skyrmions are particlelike, topologically nontrivial spin textures. Isolated represent metastable excitations of the ferromagnetic ground state and can be long-lived. For potential applications such as memory logic devices, it is essential to quantitatively understand their stability against thermal fluctuations. Here, authors apply transition theory directly compute lifetimes isolated for two annihilation mechanisms: escape through a boundary collapse. The internal modes skyrmion...
The Dzyaloshinskii-Moriya interaction in ultrathin ferromagnets can result nonreciprocal propagation of spin waves. We examine theoretically how wave power flow is influenced by this interaction. show that the combination dipole-dipole and interactions unidirectional caustic beams Damon-Eshbach geometry. Morever, self-generated interface patterns also be induced from a point-source excitation.