A5061928654- Magnetic properties of thin films
- Magnetic Properties and Applications
- Physics of Superconductivity and Magnetism
- Theoretical and Computational Physics
- Quantum and electron transport phenomena
- Advanced Memory and Neural Computing
- Characterization and Applications of Magnetic Nanoparticles
- Magnetic and transport properties of perovskites and related materials
- Magneto-Optical Properties and Applications
- Ferroelectric and Negative Capacitance Devices
- Magnetic Properties of Alloys
- ZnO doping and properties
- Advanced Condensed Matter Physics
- Magnetic Properties and Synthesis of Ferrites
- Neural Networks and Reservoir Computing
- Intermetallics and Advanced Alloy Properties
- Topological Materials and Phenomena
- Geomagnetism and Paleomagnetism Studies
- Semiconductor materials and devices
- Force Microscopy Techniques and Applications
- Surface and Thin Film Phenomena
- Pulsed Power Technology Applications
- Tribology and Lubrication Engineering
- Metallurgical and Alloy Processes
- Geophysics and Sensor Technology
Laboratoire de physique des Solides
2016-2024
University of Trás-os-Montes and Alto Douro
2024
Centre National de la Recherche Scientifique
2014-2023
Université Paris-Saclay
2016-2023
University of Minho
2022
University of Leeds
2021
Université Paris-Sud
2013-2018
Laboratoire Albert Fert
2012-2016
Institute of Physics and Technology
2016
ON Semiconductor (United States)
2016
Magnetic skyrmions are textures behaving as quasiparticles which topologically different from other states. Their discovery in systems with broken inversion symmetry sparked the search for materials containing such magnetic phase at room temperature. topological properties combined chirality-related spin-orbit torques make them interesting objects to control magnetization nanoscale. Here we show that a pair of coupled same charge and opposite chiralities can be stabilized symmetric bilayer...
Abstract Memristors are non-volatile nano-resistors which resistance can be tuned by applied currents or voltages and set to a large number of levels. Thanks these properties, memristors ideal building blocks for applications such as multilevel memories artificial nano-synapses, the focus this work. A key point towards development scale memristive neuromorphic hardware is build neural networks with memristor technology compatible best candidates future mainstream memories. Here we show first...
A model for a spin-torque nano-oscillator based on the self-sustained oscillation of magnetic skyrmion is presented. The system involves circular nanopillar geometry comprising an ultrathin film free layer with strong Dzyaloshinkii-Moriya interaction and polariser vortex-like spin configuration. It shown that spin-transfer torques due to current flow perpendicular plane leads gyration arises from competition between geometric confinement boundary edges polarisation torques. phenomenology...
The dynamics of individual magnetic skyrmions confined in ultrathin film dots is studied theoretically. systems considered are transition-metal ferromagnets possessing perpendicular anisotropy and particular attention given to the dynamic response ac fields. By using micromagnetics simulations, it shown that breathing modes can hybridize with geometrically quantized spin wave eigenmodes circular dots, leading distinct features power spectrum differ from behavior expected for uniformly...
We carried out measurements of domain wall (DW) velocities driven by magnetic field pulses in symmetric Pt/Co/Pt and asymmetric Pt/Co/AlOx, Pt/Co/GdOx Pt/Co/Gd trilayers with ultrathin Co layers perpendicular anisotropy. In agreement theoretical models, the maximum observed velocity is much larger samples, where interfacial Dzyaloshinskii-Moriya interaction (DMI) stabilises chiral N\'eel walls, than stack. addition, very large DW speeds (up to 600 m/s) are obtained, 2.5 times samples...
The magnetostatic interaction between two oppositely charged transverse domain walls (TDWs) in adjacent Permalloy nanowires is experimentally demonstrated. dependence of the pinning strength on wire separation investigated for distances 13 and 125 nm. results can be described fully by considering distribution magnetic charge within rigid, isolated TDWs. Alternative DW internal structure cannot reproduce this observed dependence. Modeling suggests TDW not appreciably disturbed, remains rigid...
Domain wall (DW) pinning in ferromagnetic nanowires is general a complex process. Distortions of the DW shape make quantitative agreement between modeling and experiment difficult. Here we demonstrate using nanometer scale localized stray fields. This type interaction gives well-characterized, tailorable potential landscapes that do not appreciably distort DW. Our experimental results are excellent with an Arrhenius-Néel model depinning--a result only possible when modeled profile agrees...
We experimentally investigate the current-induced magnetization reversal in Pt/[Co/Ni]$_3$/Al multilayers combining anomalous Hall effect and magneto-optical Kerr techniques crossbar geometry. The occurs through nucleation propagation of a domain opposite polarity for current density order 0.3 TA/m$^2$. In these experiments we demonstrate full control each stage: i)the {\O}rsted field controls ii) domain-wall by spin torque from Pt effect. This scenario requires an in-plane magnetic to tune...
The dynamics of magnetic domain walls in ultrathin strip-patterned Pt/Co/AlOx samples with perpendicular easy axis has been studied experimentally under an easy-axis field, superposed to a hard-axis field oriented along the strip. is large so that move well beyond creep regime. A chiral effect observed where wall velocity shows monotonous and surprisingly variation in-plane field. micromagnetic analysis, combining analytic, one-dimensional, two-dimensional simulations structural disorder,...
In ferromagnetic materials, the rich dynamics of magnetic domain walls (DWs) under a field or current has been successfully described using well-known $q\ensuremath{-}\ensuremath{\varphi}$ analytical model. We demonstrate here that this simple unidimensional model holds for multiple-sublattice materials such as ferrimagnetic alloys synthetic antiferromagnets (SAFs) by effective parameters, and it is in excellent agreement with double-lattice micromagnetic simulations. obtain laws DW velocity...
Magnetic domain walls are objects whose dynamics is inseparably connected to their structure. In this work we investigate magnetic bilayers, which engineered such that a coupled pair of walls, one in each layer, stabilized by cooperation Dzyaloshinskii-Moriya interaction and flux-closing mechanism. The dipolar field mediating the between two links not only position but also We show link has direct impact on induced dynamics. demonstrate system coupling leads an increased wall velocity with...
In order to increase the thermal stability of a magnetic random access memory (MRAM) cell, materials with high spin-orbit interaction are often introduced in storage layer. As side effect, strong Dzyaloshinskii-Moriya (DMI) may arise such systems. Here we investigate impact DMI on cell performance, using micromagnetic simulations. We find that strongly promotes non-uniform magnetization states and switching modes It appears be detrimental for both its current, leading considerable...
We report on a new source of in-plane anisotropy in nanomagnets due to the presence Dzyaloshinskii-Moriya interaction (DMI). This depends shape magnet, and is orthogonal demagnetization anisotropy. effect originates from DMI energy reduction an out-of-plane tilt spins at edges oriented perpendicular magnetization. Our investigation combining experimental, numerical analytical results demonstrate that this can compensate magnets elongated shape, provided their volumes small enough thus...
Nitrogen-vacancy magnetic microscopy is employed in the quenching mode as a noninvasive, high-resolution tool to investigate morphology of isolated skyrmions ultrathin films. The skyrmion size and shape are found be strongly affected by local pinning effects field history. Micromagnetic simulations including static disorder, based on physical model grain-to-grain thickness variations, reproduce all experimental observations reveal key role disorder history stabilization This work opens way...
We demonstrate that the effects of spin-orbit coupling and inversion asymmetry exist in a single $\mathrm{Gd}\text{\ensuremath{-}}\mathrm{Fe}\text{\ensuremath{-}}\mathrm{Co}$ ferrimagnetic layer, even without heavy-metal interface. use electric transport measurements to quantify torques. measure Dzyaloshinskii-Moriya interaction using Brillouin light-scattering measurement technique, we observe resulting chiral magnetic textures x-ray photoemission electron microscopy. attribute these...
Domain walls, nanoscale transition regions separating oppositely oriented ferromagnetic domains, have significant promise for use in spintronic devices data storage and memristive applications. The state of these is related to the wall position thus rapid operation will require a controllable onset domain motion high speed displacement. These processes are traditionally driven by spin transfer torque due lateral injection polarized current through nanostrip. However, this geometry often...
In domain wall (DW) excitation experiments, nonlinearity (NL) intrinsic to the DW dynamics is often hard distinguish from perturbation due confining potential or distortion. Here we numerically investigate dynamic oscillations of magnetostatically coupled DWs: a system well understood in quasistatic limit. NL observed, even for harmonic potential, motion. This behavior principally dependent on terms normally associated with canonical momentum and contrast restoring potential. not observable...
The mechanical manipulation of magnetic nanoparticles is a powerful approach to probing and actuating biological processes in living systems. Implementing this technique high-throughput assays can be achieved using biocompatible micromagnet arrays. However, the properties these arrays are usually indirectly inferred from simulations or Stokes drag measurements, leaving unresolved questions about actual profile fields at micrometer scale exact forces that applied. Here, we exploit field...
Coaches rely on the information detected in performance environment to regulate quantity and quality of decisions made during matches. This study used an expert-novice paradigm describe coaches' gaze behavior offensive defensive game moments futsal. Twenty coaches (ten expert ten novices) participated study. The experimental conditions contrasted their when watching 71 video clips game, both team was attacking defending. dependent variables for behaviour were organized described using...
Ferrimagnetic TbFe or TbFeCo amorphous alloy thin films have been grown by coevaporation in ultrahigh vacuum. They exhibit an out-of-plane magnetic anisotropy up to their Curie temperature with a nucleation and propagation reversal mechanism suitable for current induced domain wall motion. Rutherford backscattering experiments confirmed fine control of the Tb depth-integrated composition within evaporation process. However, large set experimental techniques were used evidence interface...
The pinning of asymmetric transverse magnetic domain walls by constrictions and protrusions in thin permalloy nanowires is directly observed using the Fresnel mode imaging. Different wall (DW)/trap configurations are initialized situ applied fields, resulting imaged both at remanence under fields. nature chirality dependent potentials created traps clearly observed. effect asymmetry DW discussed. Micromagnetic simulations also presented, which excellent agreement with experiments.