A5015770876- Magnetic properties of thin films
- Quantum and electron transport phenomena
- Physics of Superconductivity and Magnetism
- Magnetic Properties and Applications
- Magnetic Properties of Alloys
- Theoretical and Computational Physics
- ZnO doping and properties
- Advanced Memory and Neural Computing
- Magnetic and transport properties of perovskites and related materials
- Characterization and Applications of Magnetic Nanoparticles
- Magneto-Optical Properties and Applications
- Multiferroics and related materials
- Advanced Condensed Matter Physics
- Topological Materials and Phenomena
- Surface and Thin Film Phenomena
- Metallic Glasses and Amorphous Alloys
- Rare-earth and actinide compounds
- Ferroelectric and Negative Capacitance Devices
- Superconducting Materials and Applications
- Heusler alloys: electronic and magnetic properties
- Electronic and Structural Properties of Oxides
- Acoustic Wave Resonator Technologies
- Semiconductor materials and devices
- Advancements in Semiconductor Devices and Circuit Design
- Mechanical and Optical Resonators
The University of Tokyo
2016-2025
RIKEN Center for Emergent Matter Science
2016-2025
Japan Science and Technology Agency
2004-2024
GlobalFoundries (Singapore)
2020-2024
GlobalFoundries (United States)
2024
GlobalFoundries (Germany)
2024
Institute for Solid State Physics and Optics
2006-2023
RIKEN
2013-2022
Japan Atomic Energy Agency
2022
Advanced Science Research Center
2022
Reversible spin Hall effect comprising the direct and inverse effects was electrically detected at room temperature. A platinum wire with a strong spin-orbit interaction is used not only as current absorber but also spin-current source in specially designed lateral structure. The obtained conductivities are 2.4 x 10(4) (Omega m)(-1) temperature, times larger than previously reported values of semiconductor systems. Spin from both experimentally confirmed to be same, demonstrating Onsager...
We have theoretically and numerically studied the dynamic properties of vortex magnetic state in soft submicron ferromagnetic dots with variable thickness diameter. To describe translation mode eigenfrequencies, we applied equation motion for collective coordinates. calculated restoring force an explicit account magnetostatic interaction on bases “rigid” two-vortices “side charges free” models. The latter model well explains results our micromagnetic numerical calculations. eigenfrequency is...
A series of interstitial ternary nitrides R2Fe17Ny with 2.3<y<2.9 has been prepared for R=Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Lu and Y. The have structures related to those Th2Zn17 or Th2Ni17, but the unit cell volumes are 6-7% greater, magnetic ordering temperatures some 400 K higher than 2:17 parent compounds. Fe-Fe exchange interactions more doubled by nitrogenation, whereas R-Fe little changed. All compounds exhibit easy-plane anisotropy at room temperature, except Sm2Fe17Ny, which...
Magnonics addresses the physical properties of spin waves and utilizes them for data processing. Scalability down to atomic dimensions, operation in GHz-to-THz frequency range, utilization nonlinear nonreciprocal phenomena, compatibility with CMOS are just a few many advantages offered by magnons. Although magnonics is still primarily positioned academic domain, scientific technological challenges field being extensively investigated, proof-of-concept prototypes have already been realized...
We have investigated spin Hall effects in 4$d$ and 5$d$ transition metals, Nb, Ta, Mo, Pd, Pt, by incorporating the absorption method lateral valve structure, where large current preferably relaxes into exhibiting strong spin-orbit interactions. Thereby nonlocal measurements enable us to evaluate their conductivities. The sign of conductivity changes systematically depending on number $d$ electrons. This tendency is good agreement with recent theoretical calculation based intrinsic effect.
We demonstrate that a giant spin Hall effect (SHE) can be induced by introducing small amount of Bi impurities in Cu. Our analysis based on new 3-dimensional finite element treatment transport shows the sign SHE is negative and its (SH) angle amounts to -0.24. Such large SH CuBi alloys explained applying resonant scattering model proposed Fert Levy [Phys. Rev. Lett. 106, 157208 (2011)] 6p impurities.
We systematically measure and analyze the spin diffusion length Hall effect in Pt with a wide range of conductivities using absorption method lateral valve devices. observe linear relation between conductivity, evidencing that relaxation is governed by Elliott-Yafet mechanism. find single intrinsic conductivity ($\sigma_{SH}^{int}=1600\pm150\: \Omega^{-1}cm^{-1}$) for full studied which good agreement theory. For first time we have obtained crossover moderately dirty superclean scaling...
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,...
Abstract The current data revolution has, in part, been enabled by decades of research into magnetism and spin phenomena. For example, milestones such as the observation giant magnetoresistance, resulting development spin-valve read head, continue to motivate device research. However, ever-growing need for higher processing speeds larger storage capabilities has caused a significant increase energy consumption environmental concerns. Ongoing spintronics should therefore reduce while...
Abstract Magnonics is a research field that has gained an increasing interest in both the fundamental and applied sciences recent years. This aims to explore functionalize collective spin excitations magnetically ordered materials for modern information technologies, sensing applications advanced computational schemes. Spin waves, also known as magnons, carry angular momenta allow transmission, storage processing of without moving charges. In integrated circuits, magnons enable on-chip data...
Here, we report the observation of strong coupling between magnons and surface acoustic wave (SAW) phonons in a thin CoFeB film constructed an on-chip SAW resonator by analyzing phonon dispersion anticrossings. We employ nanostructured design that, contrast to conventional resonators, allows us enhance shear-horizontal strain. Crucially, this type strain couples strongly magnons. Our device provides tunability thickness with fixed wavelength, which is departure from approach magnon-phonon...
Magnetization processes are analytically described for the arrays of soft ferromagnetic polycrystalline circular dots with submicron dimensions, wherein magnetization reversal accompanied by nucleation, displacement, and annihilation magnetic vortices. Magnetostatic, exchange, Zeeman energies taken into account analysis. The state each dot in an applied field is treated as off-centered rigid vortex structure; i.e., keeps its spin distribution while being displaced. This model yields...
We study the extrinsic spin Hall effect induced by Ir impurities in Cu injecting a pure current into CuIr wire from lateral valve structure. While no is observed without impurity, resistivity of increases linearly with impurity concentration. The angle CuIr, (2.1±0.6)% throughout concentration range between 1% and 12%, practically independent temperature. These results represent clear example predominant skew scattering contribution to nonmagnetic alloy.
We have studied the evolution of spin Hall effect (SHE) in regime where material size responsible for accumulation is either smaller or larger than diffusion length. Lateral valve structures with Pt insertions were successfully used to measure absorption efficiency as well induced through effect. Under a constant applied current results show decrease signal more pronounced thickness exceeds This implies that originates from bulk scattering inside wire and length limits SHE. also analyzed...
We demonstrate the method to calculate spatial distributions of spin current and accumulation in multiterminal ferromagnetic/nonmagnetic hybrid structure using an approximate electrotransmission line. The analyses based on obtained equation yield results, good agreement with experimental ones. This implies that allows us determine diffusion length additionally connected electrically floating wire from reduction signal.
The evolution of a magnetic “vortex” state in submicron ferromagnetic disks has been studied as functions disk diameter and thickness. vortex core displacement the applied field was calculated by minimizing total energy consisting magnetostatic, exchange, Zeeman energies. A simple analytical expression for initial susceptibility is deduced. increases with increasing decreasing calculations agree well experimental data obtained 60 nm thick permalloy arrays variable from 0.2 to 0.8 μm.
We have performed nonlocal spin injection into a nanoscale ferromagnetic particle configured in lateral spin-valve structure to switch its magnetization only by current. The aligns the of parallel injector. current responsible for switching is estimated from experiment be about 200 microA, which reasonable compared with values obtained conventional pillar structures. Interestingly, always occurs antiparallel particle-injector magnetic configurations, where no opposite observed. Possible...
Temperature dependence of spin relaxation process in a Cu wire has been studied by means nonlocal spin-valve measurements. The spin-diffusion length the is found to take maximum at characteristic temperature, below which reduced. mechanism reduction can be explained considering spin-flip scattering due oxidized surface wire. thickness temperature supports interpretation with oxidation.