A5013482642- Astrophysics and Star Formation Studies
- Astrophysical Phenomena and Observations
- Solar and Space Plasma Dynamics
- Fluid Dynamics and Turbulent Flows
- Astro and Planetary Science
- Topological Materials and Phenomena
- Cosmology and Gravitation Theories
- Stellar, planetary, and galactic studies
- Computational Fluid Dynamics and Aerodynamics
- Gas Dynamics and Kinetic Theory
- Galaxies: Formation, Evolution, Phenomena
- High-pressure geophysics and materials
- Geophysics and Gravity Measurements
- Field-Flow Fractionation Techniques
- Magnetic properties of thin films
- Pulsars and Gravitational Waves Research
- Astronomy and Astrophysical Research
- Spacecraft and Cryogenic Technologies
- Meteorological Phenomena and Simulations
- Gamma-ray bursts and supernovae
- Phase Equilibria and Thermodynamics
- Quantum and electron transport phenomena
- Magnetic and transport properties of perovskites and related materials
- Terahertz technology and applications
- Ionosphere and magnetosphere dynamics
The University of Tokyo
2008-2025
Mitsubishi Electric (Japan)
2024
Institute for Solid State Physics and Optics
2024
Kobe University
2002-2022
International Summer School of Photography
2019-2020
Mie University
2011-2014
Planetary Science Institute
1998
Kyoto University
1982-1992
Kawasaki Heavy Industries (Japan)
1986
University of Wales
1976-1977
We report strong terahertz (~10^12 Hz) high harmonic generation in thin films of Cd3As2, a three-dimensional Dirac semimetal at room temperature. The third harmonics is detectable with tabletop light source and can be as 100 V/cm by applying the fundamental field 6.5 kV/cm inside film, showing an unprecedented efficiency for frequency conversion. Our time-resolved spectroscopy calculations also clarify microscopic mechanism nonlinearity originating coherent acceleration electrons momentum...
Abstract Antiferromagnetic spin motion at terahertz (THz) frequencies attracts growing interests for fast spintronics, however, their smaller responses to external field inhibit device application. Recently the noncollinear antiferromagnet Mn 3 Sn, a Weyl semimetal candidate, was reported show large anomalous Hall effect (AHE) room temperature comparable ferromagnets. Dynamical aspect of such is an important issue be clarified future THz data processing. Here conductivity in Sn thin films...
Numerical calculations are performed for axisymmetric flow of inviscid ideal gas past a gravitating body. Cases based on two extreme boundary conditions the surface body, i.e. slippery condition rigid sphere and maximum accretion hollow sphere, computed compared. The results presented Mach numbers 0.6, 1.4, 2.4 5.0, ratio specific heats 1.1, 4/3, 5/3.
view Abstract Citations (141) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Nonlinear Growth of Rayleigh-Taylor Instabilities and Mixing in SN 1987A Hachisu, Izumi ; Matsuda, Takuya Nomoto, Ken'ichi Shigeyama, Toshikazu Optical, X-ray, gamma-ray light curves broad emission lines heavy elements strongly suggest the occurrence large-scale mixing during explosion. Using a two-dimensional hydrodynamic code, we have numerically demonstrated...
Two-dimensional hydrodynamic calculations of an accretion flow on to a compact object fed by stellar wind in close binary system with mass ratio unity are performed. We consider the case which is driven thermal pressure. The parameters specifying problem sound speed gas, c0, at surface mass-losing star and specific heats, γ.
Recent numerical and analytical results on disc-like accretion with shock waves as the only dissipation mechanism are compared. The global properties of process similar to those viscous (α) disc model, but precise values effective α value a function rate can be calculated. At low ratio specific heats (γ<1.45) is possible without radiative losses. Such adiabatic occur in practice at high rates mass objects may important formation planets. Following Donner, Lynden-Bell, it pointed out that...
We report magnetotransport properties for epitaxial thin films of SrFeO${}_{3}$ and SrFe${}_{0.99}$Co${}_{0.01}$O${}_{3}$ with possible skyrmion-related spin textures. Resonant soft x-ray diffraction measurements revealed formation helical structures both samples ($Q//\ensuremath{\langle}111\ensuremath{\rangle}$). From we found several distinct helimagnetic phases multiple/single $Q$ vectors. A steep suppression Hall resistivity is observed above the critical field to reach high-field...
We investigate ultrafast dynamics of the anomalous Hall effect (AHE) in topological antiferromagnet Mn_{3}Sn with sub-100 fs time resolution. Optical pulse excitations largely elevate electron temperature up to 700 K, and terahertz probe pulses clearly resolve suppression AHE before demagnetization. The result is well reproduced by microscopic calculation intrinsic Berry-curvature mechanism while extrinsic contribution excluded. Our work opens a new avenue for study nonequilibrium identify...
In this paper we study the influence of angle between local interstellar medium velocity and magnetic field vectors on interaction with solar wind. Both winds are supposed supersonic. Applicability two‐shock model is discussed. Investigation performed by numerical solution MHD equations for an ideal plasma in one‐fluid approximation.
view Abstract Citations (99) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Rayleigh-Taylor Instabilities and Mixing in the Helium Star Models for Type Ib/Ic Supernovae Hachisu, Izumi ; Matsuda, Takuya Nomoto, Ken'ichi Shigeyama, Toshikazu Motivated by necessity of large-scale mixing modeling light curves supernovae (SN Ib,Ic), (R-T) instabilities exploding helium stars masses Malpha_ = 3.3, 4, 6 M_sun_ are calculated first time with a two-...
We consider axisymmetric steady centrifugally driven thermal convection in a compressible fluid rapidly rotating circular cylinder. The Boussinesq approximation is not used, because it valid for the case of practical interest. clarify importance effect flow-induced volume change particle, and propose widely applicable method solution.
We investigated the electronic and magnetic properties of fully oxidized ${\mathrm{BaFeO}}_{3}$ thin films, which show ferromagnetic-insulating with cubic crystal structure, by hard x-ray photoemission spectroscopy (HAXPES), absorption (XAS), soft circular dichroism (XMCD). analyzed results configuration-interaction (CI) cluster-model calculations for ${\mathrm{Fe}}^{4+}$, showed good agreement experimental results. also studied ${\mathrm{SrFeO}}_{3}$ have an ${\mathrm{Fe}}^{4+}$ ion helical...
We experimentally elucidate the origin of anomalous Hall conductivity in a three-dimensional Dirac semimetal, ${\mathrm{Cd}}_{3}{\mathrm{As}}_{2}$, driven by circularly polarized light. Using time-resolved terahertz Faraday rotation spectroscopy, we determine transient spectrum with special attention to its sign. Our results clearly show dominance direct photocurrent generation assisted electric field. The contribution from Floquet-Weyl nodes is found be minor when driving light resonance...
We have synthesized BaFeOx thin films by pulsed-laser deposition followed low temperature (200 °C) oxidation to BaFeO3. X-ray diffraction indicates that fully oxidized single crystalline BaFeO3 has been formed with a lattice parameter of 3.97 Å, the bulk stoichiometric value. The state Fe is confirmed be 4+ using hard x-ray photoemission spectroscopy. A ferromagnetic ground found saturation magnetization and Curie 3.2 μB/formula unit 115 K, respectively. Unusually, for uniform cubic...
We perform 2D and 3D numerical simulations of an accretion disc in a close binary system using the simplified flux vector splitting (SFS) finite volume method. In our calculations, gas is assumed to be ideal with γ=1.01, 1.05, 1.1 1.2. The mass ratio mass-losing star mass-accreting unity. Our results show that spiral shocks are formed on all cases. calculations we find smaller γ is, more tightly winds. observe this trend as well somewhat weaker sense. Mach numbers discs less than 10. These...
view Abstract Citations (54) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Mixing in Ejecta of Supernovae. I. General Properties Two-dimensional Rayleigh-Taylor Instabilities and Width Supernovae Hachisu, Izumi ; Matsuda, Takuya Nomoto, Ken'ichi Shigeyama, Toshikazu Nonlinear growth two-dimensional (R-T) instabilities are numerically studied to apply the mixing supernova ejecta. We first present much refined calculations realistic model SN...
We consider steady non-axisymmetric source-sink flow of a perfect gas in rapidly rotating circular cylinder for the case which sources and sinks are distributed on top bottom. apply linearized analysis to small perturbation from state rigid-body rotation. show that radial pressure gradient plays an important role determination axisymmetric part field effects viscosity thermal conductivity govern overall configuration part. also transport main inner is axial confined horizontal boundary layers.
Three-dimensional hydrodynamic calculations are performed in order to investigate mass transfer a close binary system, which one component undergoes loss through wind. The ratio is assumed be unity. radius of the mass-losing star taken about quarter separation between two stars. Calculations for gases with specific heats and . Mass thermally driven so that other parameter sound speed gas on star. Here, we focus our attention features: flow patterns accretion ratio, define as rate onto...