A5056700160- Acoustic Wave Phenomena Research
- Metamaterials and Metasurfaces Applications
- Advanced ceramic materials synthesis
- Dust and Plasma Wave Phenomena
- High-pressure geophysics and materials
- Boron and Carbon Nanomaterials Research
- Ultrasonics and Acoustic Wave Propagation
- Graphene research and applications
- Energy Harvesting in Wireless Networks
- Cold Atom Physics and Bose-Einstein Condensates
- Ion-surface interactions and analysis
- Silicon Nanostructures and Photoluminescence
- Acoustic Wave Resonator Technologies
- 2D Materials and Applications
- Chemical and Physical Properties of Materials
- Semiconductor materials and devices
- Semiconductor materials and interfaces
- Wireless Power Transfer Systems
- Plasmonic and Surface Plasmon Research
- Perovskite Materials and Applications
- Silicon and Solar Cell Technologies
- Innovative Energy Harvesting Technologies
- Quantum, superfluid, helium dynamics
- Quantum and electron transport phenomena
- Advanced Chemical Physics Studies
Okayama University
2015-2024
Okayama University of Science
2022-2023
RIKEN
2020
RIKEN Center for Advanced Photonics
2020
The University of Tokyo
1992-2020
Tokushima University
2020
Pioneer (Japan)
2020
Bridge University
2014
Hokkaido University
2010
Nagoya Institute of Technology
2009
2D materials are expected to be favorable channel for field-effect transistor (FET) with extremely short length because of their superior immunity short-channel effects (SCE). Graphene, which is the most famous material, has no bandgap without additional techniques and this property major hindrance in reducing drain leakage. Therefore, finite band gap, such as transition metal dichalcogenides (TMDs, e.g. MoS2 WSe2) or phosphorene, required low power consumption FETs. Hafnium disulfide (HfS2)...
We propose a tunable metasurface consisting of an array graphene ribbons on silver mirror with SiO2 gap layer to control reflected wavefront at terahertz frequencies. The exhibit localized plasmon resonances depending their Fermi levels introduce abrupt phase shifts along the metasurface. With interference Fabry-Perot in layer, shift through system is largely accumulated, covering 0-to-2π range for full wavefront. Numerical simulations prove that wide-angle beam steering up 53° high...
Daytime radiative cooling potentially offers efficient passive cooling, but the performance is naturally limited by environment, such as ambient temperature and humidity. Here, we investigate limit of daytime under warm humid conditions in Okayama, Japan. A device, consisting alternating layers SiO2 poly(methyl methacrylate) on an Al mirror, fabricated characterized to demonstrate a high reflectance for sunlight selective thermal radiation mid-infrared region. In measurement irradiation,...
The photoisomerization of molecules is widely used to control the structure soft matter in both natural and synthetic systems. However, structural dynamics during isomerization their subsequent response are difficult elucidate due complex ultrafast nature. Herein, we describe formation higher-orientation liquid-crystalline (LC) azobenzene via linearly polarized ultraviolet light (UV) using time-resolved electron diffraction. orientation caused by trans-to-cis molecules. Our observations...
Abstract Acoustic metasurfaces, which utilize acoustically resonating structures, enable precise control as well shielding of sound waves through compact, subwavelength devices. In this study, we propose a multi-resonant metasurface design comprising decorated membrane, Helmholtz resonators, and defective pillar array. The proposed structure facilitates both absorption energy harvesting. effectiveness its multiple-resonance mechanism was validated numerical experimental analyses. Numerical...
The collisional equipartition rate between the parallel and perpendicular velocity components is calculated for a weakly correlated electron plasma that immersed in uniform magnetic field. Here, refer to direction of depends on parameter κ̄=(b̄/rc)/, where rc=(T/m)1/2/Ωc cyclotron radius b̄=2e2/T twice distance closest approach. For strongly magnetized (i.e., κ̄≫1), exponentially small (ν∼exp[−5(3πκ̄)2/5/6]). κ̄≪1), same as an unmagnetized except rc/b̄ replaces λD/b̄ Coulomb logarithm. (It...
Using ${10}^{6}$-atom molecular-dynamics simulations, we investigate dynamic fracture in nanophase ${\mathrm{Si}}_{3}{\mathrm{N}}_{4}$. The simulations reveal that intercluster regions are amorphous, and they deflect cracks give rise to local crack branching. As a result, the system is able sustain an order-of-magnitude larger external strain than crystalline We also determine morphology of surfaces: For in-plane surface profiles roughness exponent...
A two-dimensional nanocarbon, graphene, has attracted substantial interest due to its excellent properties. The reduction of graphene oxide (GO) been investigated for the mass production used in practical applications. Different processes produce different properties affecting performance final materials or devices. Therefore, an understanding mechanisms GO is important controlling functional systems. Here, we determined average structure reduced prepared via heating and photoexcitation...
Janus transition metal dichalcogenides (TMDCs), with dissimilar chalcogen atoms on each side of TMDCs, have garnered considerable research attention because the out-of-plane intrinsic polarization in monolayer TMDCs. Although a plasma process has been proposed for synthesizing TMDCs based atomic substitution surface at room temperature, formation dynamics and intermediate electronic states not completely examined. In this study, we investigated state between MoSe2 MoSeS during processing....
Dust particles in plasmas are often confined near the boundary between plasma bulk and sheath where gravitation is balanced by electrostatic force. To keep dust from running away horizontally, an potential usually applied to electrode surrounding these dusty and, under appropriate conditions, we have finite two-dimensional lattices of particles. Modeling interaction as isotropic Yukawa interaction, structures systems at low temperatures been analyzed both numerical simulations variational...
Sintering, structural correlations and mechanical behavior of nanophase silica glasses are investigated using large-scale, parallel molecular-dynamics simulations. During the sintering process, pore sizes distribution change without any discernible in morphology. The height position first sharp diffraction peak neutron static structure factor shows significant differences relative to bulk glass. effect densification on properties is also examined.
Million atom molecular-dynamics simulations are performed to investigate the structure, dynamics, and mechanical behavior of cluster-assembled ${\mathrm{Si}}_{3}{\mathrm{N}}_{4}$. These solids contain highly disordered interfacial regions with 50% undercoordinated atoms. Systems sintered at low pressures have percolating pores whose surface morphologies well characterized by two values roughness exponent, 0.46 0.86; these close experimental found Bouchaud et al. for fracture surfaces....
Transition metal dichalcogenides (TMDCs), including MoS2 and WS2, are potential candidates for next-generation semiconducting materials owing to their atomically thin structure strong optoelectrical responses, which allow flexible optoelectronic applications. Monolayer TMDCs have been grown utilizing chemical vapor deposition (CVD) techniques. Enhancing the domain size with high crystallinity forming heterostructures important topics practical In this study, of monolayer WS2 increased via...
Abstract Electron transfer is a fundamental energy conversion process widely present in synthetic, industrial, and natural systems. Understanding the electron important to exploit uniqueness of low-dimensional van der Waals (vdW) heterostructures because interlayer produces function this class material. Here, we show occurrence an one-dimensional layer-stacking carbon nanotubes (CNTs) boron nitride (BNNTs). This observation makes use femtosecond broadband optical spectroscopy, ultrafast...
An interatomic potential model has been developed for molecular-dynamics simulations of TiO2 (rutile) based on the formalism Streitz and Mintmire [J. Adhes. Sci. Technol. 8, 853 (1994)], in which atomic charges vary dynamically according to generalized electronegativity equalization principle. The present reproduces vibrational density states, pressure-dependent static dielectric constants, melting temperature, surface relaxation rutile crystal, as well cohesive energy, lattice elastic...
The lowest-energy state of spherical clusters made up single-species charged particles in a three-dimensional confining potential is investigated by molecular dynamics simulations for system size $5\ifmmode\times\else\texttimes\fi{}{10}^{3}$ to $1.2\ifmmode\times\else\texttimes\fi{}{10}^{5}$. energy per particle compared between shell-structured and finite-bcc lattices with relaxed surfaces. shell structure the interior configuration ion numbers lower than about ${10}^{4}$, while higher...
Structure, mechanical properties, and sintering of nanostructured SiC (n-SiC) are investigated with neutron scattering molecular-dynamics (MD) techniques. Both MD the experiment indicate onset around 1500 K. During sintering, pores shrink while maintaining their morphology: fractal dimension is ∼2 surface roughness exponent ∼0.45. Structural analyses reveal that interfacial regions in n-SiC disordered nearly same number three- fourfold coordinated Si atoms. The elastic moduli scale density...
By computer-simulation and analytic studies for binding energies microscopic shell structures, it is shown that Coulomb clusters assume particularly stable configurations at certain ``magic numbers'' of particles. Through analyses with the spherical Voronoi numbers, a special role icosahedral geometry plays in shaping particle on surfaces elucidated. Gross features cluster such as radii intershell partition particles, are well accounted by an appropriate model.
Sintering of Si3N4nanoclusters is investigated with the molecular-dynamics approach. At 2000 K thermally rough nanocrystals develop an asymmetric neck in 100 picoseconds. The contains more fourfold than threefold coordinated Si atoms. Amorphous nanoclusters a symmetric which has nearly equal number and In both cases, sintering driven by surface diffusion N much rapid joining amorphous region nanocrystals.
The structure of spherical clusters composed Yukawa particles is analyzed by molecular dynamics simulations and theoretical approaches as a model for dust in dusty plasmas the isotropic environment. latter condition expected to be realized under microgravity or active cancellation effect gravity on ground. It found that, at low temperatures, form shells and, when scaled mean distance, almost independent strength screening including case Coulomb interaction. positions populations conditions...
A technique of selective electroless plating onto PLA-ABS (Polylactic Acid-Acrylonitrile Butadiene Styrene) composite structures fabricated by three-dimensional (3D) printing is demonstrated to construct 3D microwave metamaterials. The reducing activity the PLA surface selectively enhanced chemical modification involving Sn2+ in a simple wet process, thereby forming highly conductive Ag-plated membrane only surface. metamaterial composed and non-plated ABS parts characterized experimentally...
Chiral nature of an enantiomer can be characterized by circular dichroism (CD) spectroscopy, but such a technique usually suffers from weak signal even with sophisticated optical instrument. Recent demonstrations plasmonic metasurfaces showed that chiroptical interaction molecules engineered, thereby greatly simplifying measurement system high sensing capability. Here, exploiting super-chiral field in metasurface, we experimentally demonstrate high-sensitive vibrational CD spectroscopy...