A5051931993- Magnetic properties of thin films
- Physics of Superconductivity and Magnetism
- Magnetic Properties and Applications
- Theoretical and Computational Physics
- Magnetic Properties of Alloys
- Magnetic and transport properties of perovskites and related materials
- ZnO doping and properties
- Quantum and electron transport phenomena
- Multiferroics and related materials
- Advanced Memory and Neural Computing
- Characterization and Applications of Magnetic Nanoparticles
- Metallurgical and Alloy Processes
- Neural Networks and Reservoir Computing
- Chemical and Physical Properties of Materials
- Surface and Thin Film Phenomena
- Advanced Condensed Matter Physics
- Superconductivity in MgB2 and Alloys
- Aluminum Alloys Composites Properties
- Metal and Thin Film Mechanics
- Neural Networks and Applications
- Magneto-Optical Properties and Applications
- Advanced Materials Characterization Techniques
- Quantum many-body systems
Spintronics Research Network of Japan
2017-2024
Tohoku University
2016-2024
Johannes Gutenberg University Mainz
2021-2024
Advanced Institute of Materials Science
2019
Skyrmion, a topologically-protected soliton, is known to emerge via electron spin in various magnetic materials. The skyrmion can be driven by low current density and has potential stabilized nanoscale, offering new directions of spintronics. However, there remain some fundamental issues widely-studied ferromagnetic systems, which include difficulty realize stable ultrasmall skyrmions at room temperature, presence the Hall effect, limitation velocity owing topological charge. Here we show...
Reservoir computing (RC) has been considered as one of the key computational principles beyond von-Neumann computing. Magnetic skyrmions, topological particle-like spin textures in magnetic films are particularly promising for implementing RC, since they respond strongly nonlinearly to external stimuli and feature inherent multiscale dynamics. However, despite several theoretical proposals that exist skyrmion reservoir computing, experimental realizations have elusive until now. Here, we...
The ever-growing demand for device miniaturization and energy efficiency in data storage computing technology has prompted a shift towards antiferromagnetic topological spin textures as information carriers. This is primarily owing to their negligible stray fields, leading higher possible density potentially ultrafast dynamics. We realize this work such chiral in-plane namely merons, antimerons, bimerons synthetic antiferromagnets by concurrently engineering the effective perpendicular...
A key issue for skyrmion dynamics and devices are pinning effects present in real systems. While posing a challenge the realization of conventional skyrmionics devices, exploiting can enable non-conventional computing approaches if details samples quantified understood. We demonstrate that using thermal dynamics, we characterize sample ascertain spatially resolved energy landscape. To understand mechanism pinning, probe strong size shape dependence pinning. Magnetic microscopy imaging...
Abstract In an effort to understand skyrmion behavior on a coarse-grained level, skyrmions are often described as 2D quasiparticles evolving according the Thiele equation. Interaction potentials key missing parameters for predictive modeling of experiments. Here, Iterative Boltzmann Inversion technique commonly used in soft matter simulations is applied construct skyrmion-skyrmion and skyrmion-magnetic material boundary interactions from single experimental measurement without any prior...
In condensed matter physics, magnetic skyrmions, topologically stabilized solitons, have been discovered in various materials systems, which has intrigued the community terms of not only fundamental physics but also with respect to engineering applications. particular, skyrmions thin films are easily manipulable by electrical means even at room temperature. Concomitantly, a variety possible applications proposed and proof-of-concept devices demonstrated. Recently, field skyrmion-based...
We observe magnetic domain structures of MgO/CoFeB with a perpendicular easy axis under an electric field. The structure shows maze pattern electric-field dependent isotropic period. analysis the period indicates major role modulation interfacial anisotropy for observation and possible contribution from exchange stiffness constant.
We investigate the electric-field effect on exchange stiffness constant in a CoFeB/MgO junction through observation of spin-wave resonance nanoscale magnetic tunnel junction. evaluate dependence from separation between fields for Kittel and modes under electric fields. The obtained increases when interfacial electron density is decreased. This consistent with that determined dependent domain structures.
The electric-field control of magnetism is a highly promising and potentially effective approach for realizing energy-efficient applications. Recent interest has focused on the magneto-ionic effect in synthetic antiferromagnets, driven by its potential to enable high-density data storage devices with ultra-low power consumption. However, underlying mechanism responsible interlayer exchange coupling remains elusive. In our work, we find that modulation sensitive thickness ferromagnetic layer....
Using several material systems with various magnitudes of the interfacial Dzyaloshinskii-Moriya interaction (DMI), we elucidate a critical influence domain wall (DW) anisotropy on current-induced hysteresis loop shift scheme widely employed to determine magnitude effective field (${H}_{\mathrm{DMI}}$). Taking into account DW in analysis shift, which has not been included original model [Phys. Rev. B 93, 144409 (2016)], show that it provides quantitative agreement ${H}_{\mathrm{DMI}}$...
Spin torque is a promising tool for driving magnetization dynamics computing technologies. These torques can be easily produced by spin-orbit effects, but most conventional spin source materials, high degree of crystal symmetry limits the geometry produced. Magnetic ordering one way to reduce material and allow exotic torques, antiferromagnets are particularly because they robust against external fields. We present ferromagnetic resonance (ST-FMR) measurements second harmonic Hall...
We investigate the effect of Dzyaloshinskii-Moriya interaction (DMI) on domain wall (DW) configurations in W/(Co)FeB/MgO structures with varying ferromagnet (FM) thicknesses. The DW chirality and effective DMI field are evaluated from field-induced motion. results indicate a reversal FM thickness irrespective material (CoFeB or FeB) crystallographic phase W (α β phase). observed change magnitude is supported by an additional measurement spin-orbit torque assisted magnetization switching...
We report current-induced magnetization switching in Pt/Co/Ir/Co/Pt multilayers with different Ir layer thicknesses (tIr), where the perpendicularly magnetized Co layers are coupled ferromagnetically or antiferromagnetically through an interlayer exchange coupling and sandwiched by Pt spin Hall layers. The domain structures formed during vary depending on alignment, i.e., a configuration. These results clarify macroscopic picture of process for exchange-coupled systems. local is also...
We investigate a variation of magnetic domain pattern in demagnetized perpendicular-easy-axis CoFeB/MgO stacks with wide-range electric field and discuss the electric-field effect on exchange stiffness constant AS. observe non-linear period DP applied field, contrast to effective perpendicular anisotropy HKeff that is evaluated from ferromagnetic resonance shows linear response. An analysis based model describing relation AS suggests varies non-linearly implying an involved characteristic...
Topological spin textures in magnetic materials beyond two-dimensional skyrmions have attracted attention for electronics CMOS technologies. In particular, three-dimensional (3D) topological are promising due to the expected complex non-linear dynamics as well high static and dynamic thermal stability. multilayer heterostructures, a hybrid chiral skyrmion tube is well-known example of 3D texture, exhibiting an intriguing chirality transition along thickness direction. This progresses from...
We observe magnetic domain structures of MgO/CoFeB with a perpendicular easy axis under an electric field. The structure shows maze pattern electric-field dependent isotropic period. find that the modulation period is explained by considering exchange stiffness constant in addition to known anisotropy modulation.
We investigate spin-wave resonance in nanoscale CoFeB/MgO magnetic tunnel junctions (MTJs) with a perpendicular easy axis and various free-layer sizes. Two types of MTJs are fabricated by different process conditions, the is measured homodyne-detected ferromagnetic resonance. focus on distance between frequencies uniform modes as function size order to examine effect edge state MTJs. A marked difference observed two MTJs, result consistently reproduced model assuming free- or fixed-edge...
Reservoir computing (RC) has been considered as one of the key computational principles beyond von-Neumann computing. Magnetic skyrmions, topological particle-like spin textures in magnetic films are particularly promising for implementing RC, since they respond strongly nonlinear to external stimuli and feature inherent multiscale dynamics. However, despite several theoretical proposals that exist skyrmion reservoir computing, experimental realizations have elusive until now. Here, we...
Magnetic skyrmions, topologically-stabilized spin textures that emerge in magnetic systems, have garnered considerable interest due to a variety of electromagnetic responses are governed by the topology. The topology creates microscopic gyrotropic force also causes detrimental effects, such as skyrmion Hall effect, which is well-studied phenomenon highlighting influence on deterministic dynamics and drift motion. Furthermore, anticipated substantial impact stochastic diffusive motion;...
In an effort to understand skyrmion behavior on a coarse-grained level, skyrmions are often described as 2D quasi particles evolving according the Thiele equation. Interaction potentials key missing parameters for predictive modeling of experiments. We apply Iterative Boltzmann Inversion technique commonly used in soft matter simulations construct skyrmion-skyrmion and skyrmion-magnetic material boundary interactions from single experimental measurement without any prior assumptions...
The current-induced magnetization switching was investigated for Pt/Co/Ir/Co/Pt films. measurements based on the conventional four-probe method and domain structure imaging revealed that macroscopic process is considerably dependent magnetic structures. dynamics of spin-orbit torque are also shown using macrospin numerical calculation both antiferromagnetically- ferromagnetically-coupled cases sandwiched by spin Hall layers. present results provide microscopic pictures mechanism interlayer...
The ever-growing demand for device miniaturization and energy efficiency in data storage computing technology has prompted a shift towards antiferromagnetic (AFM) topological spin textures as information carriers, owing to their negligible stray fields, leading possible high density potentially ultrafast dynamics. We realize, this work, such chiral in-plane (IP) textures, namely merons, antimerons, bimerons synthetic antiferromagnets by concurrently engineering the effective perpendicular...