A5020183124- Magnetic properties of thin films
- Heusler alloys: electronic and magnetic properties
- Magnetic Properties and Applications
- Magnetic and transport properties of perovskites and related materials
- ZnO doping and properties
- Magneto-Optical Properties and Applications
- Magnetic Properties of Alloys
- Physics of Superconductivity and Magnetism
- Quantum and electron transport phenomena
- Metallic Glasses and Amorphous Alloys
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Multiferroics and related materials
- MXene and MAX Phase Materials
- Advanced Memory and Neural Computing
- Characterization and Applications of Magnetic Nanoparticles
- Magnetic Properties and Synthesis of Ferrites
- Organic Light-Emitting Diodes Research
- Semiconductor Quantum Structures and Devices
- Terahertz technology and applications
- Crystallography and molecular interactions
- Electromagnetic wave absorption materials
- Photonic and Optical Devices
- Magnetism in coordination complexes
- Magnetic Field Sensors Techniques
Tohoku University
2016-2025
Advanced Institute of Materials Science
2016-2025
Spintronics Research Network of Japan
2017-2024
Institute for Materials Research, Tohoku University
2009-2020
Abilities In Motion
2017-2020
National Institute of Advanced Industrial Science and Technology
2019
Center for Strategic and International Studies
2019
Kyoto Institute of Technology
2018
RIKEN Center for Emergent Matter Science
2017
Sendai University
2016
Ferromagnetic resonance (FMR) was measured for Cu/permalloy (Py) (20, 30, 40 \AA{})/Cu ${(d}_{\mathrm{Cu}})/\mathrm{Pt}$ (0, 50 \AA{}) films with various ${d}_{\mathrm{Cu}}$ to clarify the effect of spin diffusion driven by precession magnetization on Gilbert damping. The peak-to-peak linewidth $\ensuremath{\Delta}{H}_{\mathrm{pp}}$ FMR spectra Cu/Py/Cu/Pt very large at ${d}_{\mathrm{Cu}}=0\mathrm{\AA{}},$ and decreased remarkably ${d}_{\mathrm{Cu}}=30\mathrm{\AA{}}.$ Above...
Spin precession with frequencies up to 280 GHz is observed in Mn(3-δ)Ga alloy films a perpendicular magnetic anisotropy constant K(u)∼15 M erg/cm(3). The damping α, characterizing macroscopic spin relaxation and being key factor spin-transfer-torque systems, not larger than 0.008 (0.015) for the δ=1.46 (0.88) film. Those are about one-tenth of α values known materials large K(u). First-principles calculations well describe both low K(u) these alloys.
The Technical Committee of the IEEE Magnetics Society has selected 7 research topics to develop their roadmaps, where major developments should be listed alongside expected timelines; (i) hard disk drives, (ii) magnetic random access memories, (iii) domain-wall devices, (iv) permanent magnets, (v) sensors and actuators, (vi) materials (vii) organic devices. Among them, for spintronic devices have been surveyed as first exercise. In this roadmap exercise, we targeted tunnel spin-valve...
The out-of-plane angular dependence of ferromagnetic resonance (FMR) was measured for NM/80NiFe(Py)/NM (NM=Cu, Ta, Pd and Pt) films with various Py, Cu Ta thicknesses fabricated by magnetron sputtering. dependences FMR field linewidth were analyzed using Landau-Lifshitz-Gilbert equation taking account broadening due to magnetic inhomogeneities in a film. Magnetic assumed be the fluctuation magnitude direction effective demagnetization which contains both perpendicular anisotropy calculations...
Gilbert damping for the epitaxial Co2FeAl Heusler alloy films was investigated. constant evaluated by analyzing data of ferromagnetic resonance measured at frequency 2–20 GHz. film without annealing rather large, while it decreased remarkably with postannealing. annealed 600 °C ≃0.001. These behavior can be well explained fact that density states calculated from first principles decreases increasing degree B2 order.
Transport properties in magnetic tunnel junctions (MTJs) with Co2FexMn1−xSi (CFMS, x=0–1.0)/Al–O/Co75Fe25 structure and Gilbert damping constant the epitaxial CFMS films were investigated. The magnetoresistance ratio is as high 75% MTJs x=0.6 at room temperature. minimal x=0.4. Relations between half-metallicity examined, revealing that small half-metallic films.
We report on epitaxial growth and magnetic properties of Mn2.5Ga thin films, which were deposited Cr/MgO single crystal substrates by magnetron sputtering. X-ray diffraction results revealed the relationships as Mn2.5Ga(001)[100]∥Cr(001)[110]∥MgO(001)[100]. The presence (002) (011) superlattice peaks indicates that films crystallized into DO22 ordered structures. perpendicular anisotropy (PMA) found to be related extent chemical ordering. A giant PMA (Kueff=1.2×107 erg/cm3) low saturation...
To investigate the correlation between perpendicular magnetic anisotropy and intrinsic Gilbert damping, time-resolved magneto-optical Kerr effect was measured in Pt/Co(dCo)/Pt films. These films showed magnetization at dCo=1.0 nm a energy Kueff that inversely proportional to dCo. With an analysis based on Landau–Lifshitz–Gilbert equation, damping constant α evaluated by parameter-fitting of frequency lifetime expressions experimental data angular variations spin precession life-times. The...
Mn-Ga binary alloys show strong magnetism and large uniaxial magnetic anisotropy even though these do not contain any noble, rare-earth metals or elements. We investigate the composition dependence of saturation magnetization ${M}_{\mathrm{S}}$ ${K}_{\mathrm{u}}$ in epitaxial films Mn${}_{x}$Ga${}_{1\ensuremath{-}x}$ ($x\ensuremath{\sim}0.5$--0.75) grown by magnetron sputtering. The values decrease linearly from approximately 600 to 200 emu/cm${}^{3}$ with increasing $x$, whereas slightly 15...
We propose a new-type of thermopile consisting two ferromagnetic materials with anomalous Nernst effects (ANEs) opposite signs. L10-FePt and L10-MnGa have been chosen as the because they show large ANEs The combination perpendicularly magnetized FePt MnGa wires enhances ANE voltage effectively. in in-plane films induced by applying perpendicular temperature difference shows no variation against film thickness, which is promising characteristic for thermoelectric applications internal...
The authors present a comparative study of magnetization dynamics in Ta/CoFeB/MgO and Ta/CoFeB/Ta tunnel junctions using time-resolved magneto-optical Kerr effect. CoFeB/MgO magnetic have recently received significant attention as candidates for spintronics applications.
Material dependence of the anomalous Nernst effect (ANE) in perpendicularly magnetized ordered-alloy thin films is systematically investigated. The ANE was found to have a tendency increase simply as uniaxial magnetic anisotropy increased at room temperature. increases temperature from 10 300 K for all materials. However, signs Fe-based ordered-alloys (L10-FePt and L10-FePd) Co/Ni multilayer are opposite those Mn-based (L10-MnGa D022-Mn2Ga). Ordered-alloys with larger anisotropies reveal...
Abstract We developed tunnel magneto-resistive (TMR) sensors based on magnetic junctions (MTJs) that are able to detect a weak, sub-pT, field at low frequency. Small detectivities of 0.94 pT/Hz 1/2 1 Hz and 0.05 kHz were achieved by lowering the resistance MTJs enhancement signal using thick CoFeSiB layer flux concentrators. demonstrated real-time measurement magnetocardiography (MCG) nuclear resonance (NMR) protons sensors. This result shows both MCG NMR can be measured same system with...
We investigated photon-helicity–induced magnetization precession in Co1−xPtx alloy thin films. In addition to field-like torque, attributable magnetic field generation owing the "inverse Faraday effect," we observed nontrivial and large damping-like torque that has never been discussed for single ferromagnetic layer. The composition dependence of these two torques is effectively elucidated by a model considers mutual coupling via spin-orbit interaction between electronic orbital angular...
Fast magnetization precession is observed in L10-FePt alloy epitaxial thin films excited and detected by all-optical means. The frequency varies from 45 to 65 GHz depending on the applied magnetic field strength direction, which can be explained a uniform model taking account of first- second-order uniaxial anisotropy. lowest effective Gilbert damping constant has minimum value 0.055, about half that Co/Pt multilayers comparable Ni/Co with perpendicular
In this work, we study magnon-magnon coupling in synthetic antiferromagnets (SyAFs) using microwave spectroscopy at room temperature. Two distinct spin-wave modes are clearly observed and hybridised degeneracy points. We provide a phenomenological model that captures the phenomena experimentally demonstrate strength is controlled by out-of-plane tilt angle as well interlayer exchange field. numerically show spin-current mediated damping SyAFs plays role influencing strength.
We report the structural and magnetic properties of CoFeMnSi equiatomic quaternary Heusler alloy thin films. The epitaxial growth single-crystalline films with full $B2$ partial $L{2}_{1}$ ordering on Cr-buffered MgO(001) substrate was achieved using in situ postannealing at temperature (${T}_{\mathrm{a}}$) $500\ensuremath{-}600{\phantom{\rule{0.16em}{0ex}}}^{\ensuremath{\circ}}\mathrm{C}$. A saturation magnetization value about...
Laser-induced terahertz (THz) emission in Ta/CoFeB/MgO films with various thicknesses of CoFeB and for annealing temperatures was studied. The THz intensity exhibited its maximum value a layer thickness approximately 1.0 nm, this enhanced by 1.5 times at 300 °C. A correlation found the dependence between saturation magnetization, conductivity, intensity. origin enhancement due to discussed terms increase mean free path majority spin hot electrons crystallization annealing.
Tunnel magnetoresistance (TMR) in MgO-based magnetic tunnel junctions (MTJs) with equiatomic quaternary CoFeMnSi Heusler and CoFe alloy electrodes is studied. The epitaxial MTJ stacking structures were prepared using ultrahigh-vacuum magnetron sputtering, where the electrode has a full B2 partial L21 ordering crystal structure. Maximum TMR ratios of 101% 521% observed at room temperature 10 K, respectively, for MTJs. large bias voltage dependence ratio was also low (LT), as similarly Co2MnSi...
The magnetic damping constant in a series of Co2MnAlxSi1−x and Co2FexMn1−xSi Heusler alloy epitaxial films were systematically investigated by using ferromagnetic resonance technique. determined is roughly proportional to the density states at Fermi energy first principle calculation. result consistent with theoretical prediction when taking spin-orbit interaction into account. small Gilbert for fabricated other than film x>0.6 can be originated half-metallic electronic structure alloys.