A5067945072- Advanced Thermoelectric Materials and Devices
- 2D Materials and Applications
- Physics of Superconductivity and Magnetism
- Crystallization and Solubility Studies
- Chalcogenide Semiconductor Thin Films
- Superconductivity in MgB2 and Alloys
- High-pressure geophysics and materials
- Crystallography and molecular interactions
- X-ray Diffraction in Crystallography
- Semiconductor materials and interfaces
- Inorganic Chemistry and Materials
- Organic and Molecular Conductors Research
- Quantum, superfluid, helium dynamics
- Machine Learning in Materials Science
- Perovskite Materials and Applications
- High voltage insulation and dielectric phenomena
- Electrostatic Discharge in Electronics
- Particle accelerators and beam dynamics
- Lightning and Electromagnetic Phenomena
- Gyrotron and Vacuum Electronics Research
- Pulsed Power Technology Applications
- Inorganic Fluorides and Related Compounds
- Organometallic Compounds Synthesis and Characterization
- Electronic and Structural Properties of Oxides
- Heusler alloys: electronic and magnetic properties
Kawasaki Medical School
2024
Binghamton University
2023-2024
RIKEN Center for Emergent Matter Science
2022-2024
Osaka University
2017-2021
Nichia Corporation (Japan)
1995-2007
Tokyo Institute of Technology
1979-2001
Tokushima University
2000
Osaka Institute of Technology
1980-1986
Abstract EPW is an open-source software for ab initio calculations of electron–phonon interactions and related materials properties. The code combines density functional perturbation theory maximally localized Wannier functions to efficiently compute coupling matrix elements, perform predictive temperature-dependent properties phonon-assisted quantum processes in bulk solids low-dimensional materials. Here, we report on significant developments the since 2016, namely: a transport module...
Thermoelectric devices convert heat flow to charge flow, providing electricity. Materials for highly efficient must satisfy conflicting requirements of high electrical conductivity and low thermal conductivity. Thermal in caged compounds is known be suppressed by a large vibration guest atoms, so-called rattling, which effectively scatters phonons. Here, the crystal structure phonon dynamics tetrahedrites (Cu,Zn)12 (Sb,As)4 S13 are studied. The results reveal that Cu atoms planar...
The Lifshitz transition, a change in Fermi surface topology, is likely to greatly influence exotic correlated phenomena solids, such as high-temperature superconductivity and complex magnetism. However, since the observation of surfaces generally difficult strongly systems, direct link between transition quantum has been elusive so far. Here, we report marked impact pressure-induced on thermoelectric performance for SnSe, promising material without strong electron correlation. By applying...
We theoretically investigate how each orbital and valley play a role in high thermoelectric performance of SnSe. In the hole-doped regime, two kinds valence band valleys contribute to its transport properties: one is near U-Z line, mainly consisting Se-${p}_{z}$ orbitals, other along $\mathrm{\ensuremath{\Gamma}}$-Y Se-${p}_{y}$ orbitals. Whereas former plays major determining properties at room temperature, latter also offers comparable contribution so structure exhibits multivalley...
In this study, we combine the ab initio Migdal-Eliashberg approach with intermediate representation of Green's function, enabling accurate and efficient calculations momentum-dependent superconducting gap function while fully considering effect Coulomb retardation. Unlike conventional scheme that relies on a uniform sampling across Matsubara frequencies, demanding hundreds to thousands points, works fewer than 100 sampled functions. The developed methodology is applied investigate properties...
Spin-orbit coupling, which enriches the spin-charge entanglement, can be a key factor for novel spintronic functions. Here, authors discovered giant magnetoresistance in two-dimensional magnetic semiconductor AgCrSe${}_{2}$, is manifestation of unique band-edge modulation owing to spin-orbit coupling combined with p-d exchange interaction. By contrast common semiconductors, present system exhibits positive as large 400 %, when carrier concentration tuned critical value. This study...
Synchrotron-based angle-resolved photoemission spectroscopy is used to determine the electronic structure of layered SnSe, which was recently turned out be a potential thermoelectric material. We observe that top valence band consists two nearly independent hole bands, whose tops differ by ∼20 meV in energy, indicating necessity multivalley model describe properties. The estimated effective masses are anisotropic, with in-plane values 0.16–0.39 m0 and an out-of-plane value 0.71 m0, where...
Herein, we present the case of a 76-year-old man diagnosed with an iliopsoas abscess 3 months prior and consequently administered metronidazole. The patient visited our facility complaining difficulty in speaking feeling unsteady when walking. Neurological findings showed dysarthria, nystagmus, bilateral cerebellar ataxia. Head MRI-FLAIR demonstrated symmetrical hyperintensities dentate nuclei, red nucleus, periaqueductal midbrain, periventricular third ventricle, corpus callosum. Although...
Gold is one of the most inert metals, forming very few compounds, and only a them are currently known to be superconducting. Here we have found yet another chemical compound gold (and silver) that
In this study, we perform a comparative theoretical study on the thermoelectric performance of materials with $\mathrm{Cu}C{h}_{4}$ ($Ch=$ S, Se) tetrahedra, including famous BiCuSeO and tetrahedrite ${\mathrm{Cu}}_{12}{\mathrm{Sb}}_{4}{\mathrm{S}}_{13}$, by means first-principles calculations. By comparing these electronic band structures, find that many possess Cu-${t}_{2g}$ structure consisting quasi-one-dimensional dispersions isotropic (two-dimensional for layered compounds) dispersion...
Abstract This paper describes a newly developed impulse voltage generator (IG). It has the following features: (1) The IG consists of three components (a 1.6 MV unit, 1.4‐MV unit and base box); this facilitates mounting on 10‐ton trucks, therefore making it easier to move test field. (2) Capacitors, discharge gaps control are enclosed in fiber‐reinforced plastics, possible use all weather. (3) can generate several ten kA when load is few Ω. (4) Composition circuits for lightning/switching...
The paper deals with the applications of a chopper to thyristor Scherbius which recovers slip power wound rotor induction machine. An analysis steady-state performance this system is presented. improves in several characteristics conventional system. In particular, low factor, disadvantage Scherbius, significantly improved. A reasonable operation can realise shorter overlapping interval at commutation inverter. recovery current controlled by has pulse-width modulated (PWM) waveform. Such PWM...
The relation between the growth shapes and supersaturations and/or supercoolings was investigated in Na2S2O3 5H2O crystals: (i) changed from a hexagonal prismatic crystal, aggregate of platy crystals to spherulite with an increase supercooloings. (ii) deposition rate suddenly increased at certain supersaturation supercooling, where shape prism crystals. (iii) rates spherulites become higher increasing solute concentrations. (iv) formation process were situ observed by Schlieren Mach-zehnder...
Based on first-principles calculations, we study the electron-phonon scattering effect resistivity in zirconium dichalcogenides, ${\text{Zr}}_{}{\text{S}}_{2}$ and ${\text{Zr}}_{}{\text{Se}}_{2}$, whose electronic band structures possess multiple valleys at conduction minimum. The computed exhibits nonlinear temperature dependence, especially for ${\text{Zr}}_{}{\text{S}}_{2}$, which is also experimentally observed some transition metal dichalcogenides such as ${\text{Ti}}_{}{\text{S}}_{2}$...
In this study, we combine the ab initio Migdal-Eliashberg approach with intermediate representation for Green's function, enabling accurate and efficient calculations of momentum-dependent superconducting gap function while fully considering effect Coulomb retardation. Unlike conventional scheme that relies on a uniform sampling across Matsubara frequencies - demanding hundreds to thousands points works fewer than 100 sampled functions. The developed methodology is applied investigate...
Migdal-Eliashberg theory is one of the state-of-the-art methods for describing conventional superconductors from first principles. However, widely used implementations assume a constant density states around Fermi level, which hinders proper description materials with distinct features in its vicinity. Here, we present an implementation within EPW code that considers full electronic structure and accommodates scattering processes beyond surface. To significantly reduce computational costs,...
NICHICON (KUSATSU) CORPORATION and KEK have developed a novel long-pulse klystron modulator for both of single-beam tube (136kVp*100A) multi-beam (120kVp*140A). The main features are; - crowbar-less system with optimized IGBT snubber circuit, compact highly reliable Self-Healing capacitors, HV & LV twin pulse transformers laminated steel core reduced tank volume.