A5101833861- Iron-based superconductors research
- Topological Materials and Phenomena
- Physics of Superconductivity and Magnetism
- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Rare-earth and actinide compounds
- Advanced Condensed Matter Physics
- Surface and Thin Film Phenomena
- Quantum many-body systems
- Electronic and Structural Properties of Oxides
- Laser-Plasma Interactions and Diagnostics
- Metallurgical and Alloy Processes
- Atomic and Subatomic Physics Research
- Optical Coherence Tomography Applications
- Superconductivity in MgB2 and Alloys
- Advanced Fiber Laser Technologies
- Chalcogenide Semiconductor Thin Films
- High-pressure geophysics and materials
- Magnetic properties of thin films
- Mineralogy and Gemology Studies
- Advanced Materials Characterization Techniques
- Advanced Optical Sensing Technologies
- Corporate Taxation and Avoidance
- Graphene research and applications
- Particle accelerators and beam dynamics
The University of Tokyo
2012-2022
Institute for Solid State Physics and Optics
2022
National Institute of Information and Communications Technology
2019
University of Twente
2019
Kyoto University
2019
Topological superconductors, whose edge hosts Majorana bound states or fermions that obey non-Abelian statistics, can be used for low-decoherence quantum computations. Most of the proposed topological superconductors are realized with spin-helical through proximity effect to BCS superconductors. However, such approaches difficult further studies and applications because low transition temperatures complicated hetero-structures. Here by using high-resolution spin-resolved angle-resolved...
Abstract Photoexcitation is a very powerful way to instantaneously drive material into novel quantum state without any fabrication, and variable ultrafast techniques have been developed observe how electron, lattice, spin degrees of freedom change. One the most spectacular phenomena photoinduced superconductivity, it has suggested in cuprates that transition temperature T c can be enhanced from original with significant lattice modulations. Here, we show possibility for another high-...
The structure of the superconducting gap in unconventional superconductors holds a key to understand momentum-dependent pairing interactions. In FeSe, there have been controversial results reporting nodal and nodeless structures, raising fundamental issue mechanisms iron-based superconductivity. Here, by utilizing polarization-dependent laser-excited angle-resolved photoemission spectroscopy, we report detailed momentum dependence single- multi-domain regions orthorhombic FeSe crystals. We...
The crossover from BCS superconductivity to BEC is controlled by electronic nematicity in FeSe 1 − x S .
A topological insulator film coupled to a simple isotropic s-wave superconductor substrate can foster helical pairing of the Dirac fermions associated with surface states. Experimental realization such system is exceedingly difficult, however using novel "flip-chip" technique, we have prepared single-crystalline Bi2Se3 films predetermined thicknesses in terms quintuple layers (QLs) on top Nb substrates fresh from situ cleavage. Our angle-resolved photoemission spectroscopy (ARPES)...
Plasma current (Ip) start-up in a spherical tokamak (ST) by waves the lower-hybrid (LH) frequency range was investigated on TST-2. A low (~1 kA) ST configuration can be formed over broad (21 MHz–8.2 GHz TST-2), but further Ip ramp-up (to ~10 is most efficient with LH range. to 15 kA achieved 60 kW of net RF power PRF fast wave (FW) polarization at 200 MHz excited inductively coupled combline antenna. X-ray measurements showed that photon flux and temperature are higher direction opposite Ip,...
We have fabricated superconductor-normal metal side junctions with different barrier transparencies out of ${\mathrm{PdTe}}_{2}$ crystalline flakes and measured the differential conductance spectra. Modeling our measurements using a modified Blonder, Tinkham, Klapwijk (BTK) formalism confirms that superconductivity is mostly comprised conventional $s$-wave symmetry. found for very low transparencies, can enter thermal regime, where critical current becomes important. Adding this to BTK model...
We have developed a multi-point Thomson scattering system with double-pass configuration for the TST-2 device and installed new collection optics same. Temperature density can now be measured simultaneously at four points by using fibers polychromators. Herein, we present results of off-axis temperature anisotropy measurements performed this system, in which no beyond error bar was observed ohmic plasmas.
Interfacing bulk conducting topological Bi$_2$Se$_3$ films with s-wave superconductors initiates strong superconducting order in the nontrivial surface states. However, insulating (Bi$_{1-x}$Sb$_{x})_2$Te$_3$ on Nb instead exhibit a giant attenuation of superconductivity, even for only two-layers thick. This massive suppression proximity pairing is evidenced by ultrahigh-resolution band mappings and contrasting quantified gaps those heavily n-doped Bi$_2$Se$_3$/Nb. The results underscore...
Abstract Bogoliubov Fermi surface (BFS) is an unprecedented superconducting gap structure in which the nodal (zero-gap) region forms a two-dimensional rather than line or point. Tetragonal Fe(Se,S) having large residual density of states candidate for hosting BFSs. However, direct evidence has not yet been obtained. Here we report unique momentum dependence hole band FeSe 0.78 S 0.22 by using high-energy-resolution laser-based angle-resolved photoemission spectroscopy. We find highly unusual...
Non-inductive plasma current start-up experiments using RF power in the lower hybrid frequency range is being conducted on TST-2 spherical tokamak. Plasma currents of up to 15 kA have been achieved. The effect direct drive can be seen by comparing cases with co-drive and counter-drive. X-rays various energy ranges were measured investigate interaction between wave electrons. Soft X-ray (SX) measurements revealed that perpendicular SX emission increased significantly as increased, tangential...
We construct highly repetitive low-coherence interferometer using time-stretch technique and confirm its basic characteristics. The experimental system consists of a mode-locked laser diode (MLLD), time-stretcher, an optical interferometer, photodiode (PD), real-time oscilloscope. ultra-short pulse from MLLD was passed through dispersion flat fiber to generate supercontinuum light with 23.5 nm wavelength bandwidth. Repetition frequency the is set be 10 MHz by LiNbO3 modulator, then it feeds...