A5067691183- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Advanced Thermoelectric Materials and Devices
- Iron-based superconductors research
- Magnetic properties of thin films
- Geological and Geochemical Analysis
- Superconductivity in MgB2 and Alloys
- High-pressure geophysics and materials
- Methane Hydrates and Related Phenomena
- Quasicrystal Structures and Properties
- Rare-earth and actinide compounds
- Hydrocarbon exploration and reservoir analysis
- earthquake and tectonic studies
- Theoretical and Computational Physics
- Mineralogy and Gemology Studies
- Transition Metal Oxide Nanomaterials
- Gas Sensing Nanomaterials and Sensors
- Superconducting Materials and Applications
- Thermal properties of materials
- Spacecraft and Cryogenic Technologies
- Quantum and electron transport phenomena
- Quantum, superfluid, helium dynamics
- Geochemistry and Geologic Mapping
- Hydraulic Fracturing and Reservoir Analysis
The University of Tokyo
2015-2025
Saitama University
2022
Cryogenic Industries (United States)
2018
Novosibirsk State University
2011
Waseda University
2002-2010
Stanford Synchrotron Radiation Lightsource
2006
Stanford University
2006
Lawrence Berkeley National Laboratory
2006
Tokyo University of Science
1997-2005
Japan Science and Technology Agency
2002-2004
The anomalous Hall effect (AHE) and Nernst (ANE) are experimentally investigated in a variety of ferromagnetic metals including pure transition metals, oxides, chalcogenides, whose resistivities range over 5 orders magnitude. For these ferromagnets, the transverse conductivity ${\ensuremath{\sigma}}_{xy}$ versus longitudinal ${\ensuremath{\sigma}}_{xx}$ shows crossover behavior with three distinct regimes accordance qualitatively recent unified theory intrinsic extrinsic AHE. We also found...
We used angle-resolved photoemission spectroscopy applied to deeply underdoped cuprate superconductors Bi 2 Sr Ca (1– x ) Y Cu O 8 (Bi2212) reveal the presence of two distinct energy gaps exhibiting different doping dependence. One gap, associated with antinodal region where no coherent peak is observed, increased underdoping, a behavior known for more than decade and considered as general gap in regime. The other near-nodal regime spectrum can be did not increase less doping, previously...
The in-plane resistivity ${\ensuremath{\rho}}_{a}(T)$ and the out-of-plane ${\ensuremath{\rho}}_{c}(T)$ have been systematically measured for ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ single crystals with their oxygen contents precisely controlled. In underdoped region, deviation from $T$-linear resistivity, which evidences opening of ``spin gap,'' is clearly observed, while well reproduced by activation-type phenomenological formula...
We report superconductivity in the ternary half-Heusler compound LuPtBi, with ${T}_{c}=1.0$ K and ${H}_{c2}=1.6$ T. The crystal structure of LuPtBi lacks inversion symmetry, hence material is a noncentrosymmetric superconductor. Magnetotransport data show semimetallic behavior normal state, which evidence for importance spin-orbit interaction. combination strong coupling make candidate 3D topological superconductivity.
Quasicrystals (QCs), first discovered in 1984, generally do not exhibit long-range magnetic order. Here, we report on order the real icosahedral quasicrystals (i QCs) Au–Ga–Gd and Au–Ga–Tb. The Au65Ga20Gd15 i QC exhibits a ferromagnetic transition at TC = 23 K, manifested as sharp anomaly both susceptibility specific heat measurements, along with an appearance of Bragg peak below TC. This is observation quasicrystal, contrast to spin-glass-like behaviors observed for other found date....
We performed high-resolution angle-resolved photoemission spectroscopy on triple-layered high-Tc cuprate Bi2Sr2Ca2Cu3O10+delta. have observed the full energy dispersion (electron and hole branches) of Bogoliubov quasiparticles determined coherence factors above below EF as a function momentum from spectral intensity well based BCS theory. The good quantitative agreement between experiment theoretical prediction suggests basic validity formalism in describing superconducting state cuprates.
We discovered a ferromagnetic Au-Ga-Dy icosahedral quasicrystal (i QC), not only with high phase purity but also tunable composition. The isothermal magnetization of the polycrystalline i QC was closely investigated and mean-field-like nature transition is elucidated. Moreover, maximum Weiss temperature (θ_{p}) QCs found at electrons-per-atom (e/a) ratio 1.70 being well consistent those ACs, validating tunability magnetic properties on basis θ_{p}-e/a scheme for first time. Thus, present...
We find in the Bi2Sr2CaCu2O8+delta system that characteristic temperatures T*chi [below which uniform susceptibilities chiabT (Hperpendicularc) and chicT (Hparallelc) decrease] T*(rhoc) out-of-plane resistivity rhoc(T) shows typical upturn] coincide for all doping levels. attribute T dependence of chi's rhoc to anomalous (pseudogapped) density states (DOS) high- Tc cuprates. Furthermore, anisotropy is universal, i.e., chic approximately 1.6chiab, showing there only a single T-dependent...
We report a systematic high-resolution angle-resolved photoemission spectroscopy on high-T(c) superconductors Bi(2)Sr(2)Ca(n-1)Cu(n)O(2n+4) (n=1-3) to study the origin of many-body interactions responsible for superconductivity. For n=2 and 3, sudden change in energy dispersion, so called "kink", becomes pronounced approaching (pi,0) superconducting state, while kink appears only around nodal direction normal state. n=1, shows no significant temperature dependence even across T(c). This...
<title>Abstract</title> ARPES studies have established that the high<bold>-</bold><italic>T</italic><sub><italic>c</italic></sub> cuprates with single and double CuO<sub>2</sub> layers evolve from Mott insulator to pseudogap state a Fermi arc, on which superconducting (SC) gap opens. In four- six-layer cuprates, other hand, small hole pockets are formed in innermost planes, indicating antiferromagnetism. Here, we performed triple-layer...
Eight years since the discovery of binary antiferromagnetic (AFM) quasicrystal approximants $\mathrm{C}{\mathrm{d}}_{6}R$ [R. Tamura et al., Phys. Rev. B 82, 220201 (2010)], we report observation an AFM transition in Au-Al-R ($R=\mathrm{Gd}$ and Tb), which represent examples ternary approximants. Magnetic susceptibility, magnetization, specific heat coherently show that Tb) undergo at ${T}_{\mathrm{N}}=9.4$ 11.8 K, respectively. The transitions are found near phase boundary wide single-phase...
We investigated the composition dependence of magnetic susceptibility quasicrystal approximant Au-Al-Gd. A composition-driven ferromagnetic transition is observed in a approximant, which attributed to Ruderman-Kittel-Kasuya-Yosida (RKKY) oscillation via variation Fermi wave vector. The most simply understood as result close matching nearest and second-nearest spin distances with maximum positions RKKY potential. present work provides an idea that allows us tailor order electron concentration...
A doped quantum spin-liquid candidate transitions from one regime of superconductor electron pairing to another as pressure increases, thus widening the potential hosts unconventional superconductivity.
Research Article| August 01, 1993 Petrologic and sulfur isotopic significance of highly oxidized sulfur-rich magma Mt. Pinatubo, Philippines A. Imai; Imai 1Geological Institute, University Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113, Japan Search for other works by this author on: GSW Google Scholar E. L. Listanco; Listanco 2Earthquake 1-1-1 Yayoi, T. Fujii Author Article Information Publisher: Geological Society America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print 0091-7613 Geology...
In-plane thermal conductivity of the thermoelectric layered cobalt oxides has been measured using Harman method, in which is obtained from temperature gradient induced by applied current. We have found that charge reservoir block (the other than CoO$_2$ block) dominates conduction, where a nano-block integration concept effective for material design. further shows small but finite in-plane anisotropy between $a$ and $b$ axes, can be ascribed to misfit structure.
The superconducting gap, the pseudogap, and their doping temperature dependences have been measured by short-pulse interlayer tunneling spectroscopy for ${\mathrm{CuO}}_{2}$ triple-layer $\mathrm{h}\mathrm{i}\mathrm{g}\mathrm{h}\ensuremath{-}{T}_{\mathrm{c}}$ ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{Ca}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{10+\ensuremath{\delta}}$ system. It is found a nearly optimally doped sample that gap magnitude $\ensuremath{\approx}80\mathrm{meV}$ pseudogap...
We investigated the in-plane anisotropy on resistivity and thermopower of Bi2-xPbxSr2Co2Oy single crystals, which have a misfit structure between hexagonal CoO2 layer rock salt Bi2Sr2O4 layer. The show significantly large anisotropy, exceeds two at maximum. This would come from anisotropic pseudogap formation enhanced by structure. changes with Pb doping to take maximum x=0.4. improves thermoelectric properties through chemical pressure. power factor is as 9 muW/cmK2 100 K for x=0.6, highest...
Angle-resolved photoemission spectroscopy (ARPES) has been performed on the single- to triple-layered Bi-family high-T (c) superconductors (Bi(2)Sr(2)Ca(n-1)Cu(n)O(2n+4), n=1-3). We found a sharp coherent peak as well pseudogap at Fermi level in compound. Comparison among three compounds revealed universal rule that characteristic energies of superconducting and behaviors are scaled with maximum T (c).
The doping dependence of the thermopower, in-plane resistivity ${\ensuremath{\rho}}_{\mathrm{ab}}(T),$ out-of-plane ${\ensuremath{\rho}}_{c}(T),$ and susceptibility has been systematically measured for high-quality single crystal ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{Ca}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{10+\ensuremath{\delta}}.$ We found that transition temperature ${T}_{c}$ pseudogap formation ${T}_{{\ensuremath{\rho}}_{c}}^{*},$ below which ${\ensuremath{\rho}}_{c}$ shows a typical...