A5062314302- Magnetic properties of thin films
- ZnO doping and properties
- GaN-based semiconductor devices and materials
- Ga2O3 and related materials
- Magnetic Properties and Applications
- Semiconductor Quantum Structures and Devices
- Advanced Thermoelectric Materials and Devices
- Supramolecular Self-Assembly in Materials
- Quantum and electron transport phenomena
- Polydiacetylene-based materials and applications
- Magnetic and transport properties of perovskites and related materials
- Magnetic Properties of Alloys
- Advanced Memory and Neural Computing
- Photonic and Optical Devices
- Luminescence and Fluorescent Materials
- Semiconductor Lasers and Optical Devices
- Advancements in Semiconductor Devices and Circuit Design
- Characterization and Applications of Magnetic Nanoparticles
- Induction Heating and Inverter Technology
- Thermal Radiation and Cooling Technologies
- Theoretical and Computational Physics
- Magneto-Optical Properties and Applications
- Semiconductor materials and devices
- Electronic and Structural Properties of Oxides
- Semiconductor materials and interfaces
Tokyo Institute of Technology
2000-2020
Toshiba (South Korea)
2018
Toshiba (Japan)
2015-2017
Local structure and effective chemical valency of Mn impurity atoms incorporated in wide-band-gap (Ga,Mn)N epilayers have been investigated by using x-ray absorption fine techniques. The results provide direct evidence for the substitution majority Ga sites GaN, with an close to Mn(II), up a rather high concentration about 2 at. %. A small fraction could also form clusters.
We have studied the electronic structure of diluted magnetic semiconductor Ga$_{1-x}$Mn$_{x}$N ($x$ = 0.0, 0.02 and 0.042) grown on Sn-doped $n$-type GaN using photoemission soft x-ray absorption spectroscopy. Mn $L$-edge indicated that ions are in tetrahedral crystal field their valence is divalent. Upon doping into GaN, new state were found to form within band gap Fermi level was shifted downward. Satellite structures 2$p$ core 3$d$ partial density states analyzed configuration-interaction...
Abstract We examined the stability of writing in a magnetic domain wall device from Oersted field induced by electrical current flowing an embedded metal line. found that Joule heating raises temperature, leading to destabilization its magnetization after pulse ends abruptly. To address this issue, we suggested adding falling trailing edge main pulse, providing stabilizing while temperature reduces. adequate length fits thermal transient obtained 3D simulations. This approach improved and...
Model calculation and experimental data of circularly-polarized-light-dependent photocurrent in a n-AlGaAs/p-InGaAs/p-GaAs heterostructure are reported. It is found that, under the appropriate forward bias condition, spin voltaic effect (SVE) can survive across heterojunction give rise to detectable polarization-dependent signals which greater than due magnetic circular dichroism. Our analysis suggests that SVE be enhanced by optimization layer thickness, doping profile, applied bias, making...
We deposited perpendicularly magnetized Co(∼1nm)/Pt(6nm) bilayers by thermal chemical vapor deposition (CVD) on top of 3nm thick Pt layer using various temperature. Observed Ms increased with the increase temperature Ts, and reached value pure-Co at Ts = 500°C. measured a (left-handed) negative Dzyaloshinskii-Moriya interaction in CVD films indicating dominant role bottom Pt/Co interface.
Light-induced precession of ferromagnetically-coupled Mn spins is studied systematically in the pico- to sub-nano-second time regime through time-resolved magneto-optical signals collected by one-color, pump-and-probe experiments. Induced discussed terms a relative change magnetic anisotropy originated at least part non-thermal process. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
A study of the chemical vapor deposition (CVD) high-purity cobalt thin films is described. The Co layer prepared by a thermal CVD technique with Pt/Ta underlayer and Pt cap shows saturation magnetization (Ms) ∼1.8 T perpendicular magnetic anisotropy (PMA) an energy (Ku) ∼105 J/m3. thickness dependence Ku reveals that interfacial at Pt/Co interface most likely origin obtained PMA.
Modeling and design of a thin-film $\pi $ -type micro thermoelectric generator ($\mu TEG) using new module structure, which is powered by body heat, are demonstrated for wearable device (WD) applications. The has vacuum/insulator-hybrid isolation structure enabling it to achieve high output power, whose interspace between the cold-side convex-shape hot-side plates isolated an insulator thermopile integration region vacuum its outside region. A lumped-constant circuit model optimization...
Successful preparation of perpendicularly magnetized Co thin layers on Pt seed-layers (SLs) using atomic layer deposition (ALD) technique with Co(PF3)4H as a precursor is reported. The residual phosphorus content in the samples, due to low temperatures realize ALD, was reduced effectively by tuning ALD parameters. Spin–orbit-torque-driven current-induced domain wall motion (CIDWM) observed strip containing prepared condition.
Abstract We have investigated the electronic structure of Cr‐ and Mn‐doped GaN using photoemission spectroscopy (PES) X‐ray absorption (XAS). Cr Mn XAS at L ‐edge indicated that ions are in tetrahedral crystal field their valences trivalent divalent, respectively. Upon doping into GaN, new states were found to form band‐gap region GaN. Resonant (RPES) has revealed main 3d partial density (PDOS) appears within band gap while PDOS valence as a shoulder above valence‐band maximum indicating...
Magneto-optical imaging of a photo-induced change in magnetization (Ga,Mn)As is accomplished for the first time by using scanning laser magneto-optical microscope. Observed results clearly show importance excitation with circularly polarized light. The micron-scale reveals that details depend not only on condition but also initial state. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Physical properties of ferromagnetic p-type Ga1−xMnxAs1−yNy epitaxial films (x=0.045 and y=0–0.032) grown by molecular-beam epitaxy are described. It is found that the incorporation nitrogen gradually suppresses metallic behavior p-(Ga,Mn)As, especially at low temperatures. The Curie temperature TC decreases accordingly with increasing y value. reduction in discussed terms suppression hole-mediated long-range spin-exchange interaction due to enhancement carrier localization. Perpendicular...
A thin-film micro thermoelectric generator (μTEG) applicable to wearable devices is investigated. This μTEG module has a transverse configuration of the Seebeck elements and thus can adapt microfabrication process with material. design method maximize output developed, its performance analyzed. high power 10mW an voltage 1V could be achieved for wrist-band-style module-mounting.
Successful preparation of perpendicularly magnetized Co thin layers on Pt seed-layers using atomic layer deposition (ALD) technique with Co(PF <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> ) xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> H as a precursor is reported. The residual phosphorus content in the samples, due to low temperatures realize ALD, was reduced effectively by tuning ALD parameters. Spin-orbit-torque driven...
The motion of chiral magnetic domain walls (DWs) driven by spin-orbit torque (SOT) has been extensively studied in heavy metal/ferromagnet heterostructures with perpendicular anisotropy. This study specifically focuses on SOT-driven DWs near Bloch-states, which we refer to as ``quasi-Bloch DWs". These quasi-Bloch exhibit slower compared Neel-type DWs, offering potential for achieving highly controllable DW positions. Here, investigate the characteristics perpendicularly magnetized ultra-thin...
We have developed a three-step molecular beam deposition method to obtain crystalline polymer films directly on semiconductor substrates. This is exemplified by alkyluretane-substituted polydiacetylene (PDA-4U4) composed of lateral crystal domains one hundred square microns or larger GaAs(100) Polarization dependence Raman scattering confirms each domain formed well-aligned polymers. The blue-to-red thermochromic phase transition occurs at around 70°C, which lower than that reported for the...