A5002000026- Rare-earth and actinide compounds
- Magnetic Properties of Alloys
- Quantum Chromodynamics and Particle Interactions
- Nuclear physics research studies
- Particle physics theoretical and experimental studies
- Iron-based superconductors research
- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Silicon and Solar Cell Technologies
- Quantum, superfluid, helium dynamics
- Semiconductor materials and interfaces
- Nuclear Physics and Applications
- Atomic and Subatomic Physics Research
- Inorganic Chemistry and Materials
- Advanced NMR Techniques and Applications
- High-Energy Particle Collisions Research
- High-pressure geophysics and materials
- Lymphoma Diagnosis and Treatment
- Muon and positron interactions and applications
- Atomic and Molecular Physics
- Topological Materials and Phenomena
- Magnetic properties of thin films
- Particle Detector Development and Performance
- Radiation Detection and Scintillator Technologies
Tohoku University
2015-2024
Keio University
2022-2024
The University of Tokyo
2013-2024
RIKEN Center for Advanced Intelligence Project
2024
Kitasato University
2022
Kitasato Institute Hospital
2022
Waseda University
2020
University of the Ryukyus
2003-2017
Kansai University
2013-2015
Institute for Materials Research, Tohoku University
1988-2012
Quantum transport of quasi–two-dimensional Dirac fermions is largely controlled by magnetic order in a layered magnet.
At the Mainz Microtron MAMI, first high-resolution pion spectroscopy from decays of strange systems was performed by electron scattering off a (9)Be target in order to study Λ binding energy light hypernuclei. Positively charged kaons were detected short-orbit spectrometer with broad momentum acceptance at 0° forward angles respect beam, efficiently tagging production strangeness nucleus. Coincidentally, negatively decay pions two independent spectrometers. About 10(3) pionic weak...
We investigate magnetotransport properties in a single crystal of pyrochore-type Nd2Ir2O7. The metallic conduction is observed on the antiferromagnetic domain walls all-in-all-out-type Ir 5d moment ordered insulating bulk state that can be finely controlled by an external magnetic field along [111]. On other hand, applied [001] induces phase transition from insulator to semimetal as consequence field-induced modification Nd 4f and configurations. A theoretical calculation consistently...
Temperature dependence of the elastic constants in a series rare earth hexaborides has been investigated by means ultrasonic method. The remarkable softening transverse C 44 mode PrB 6 , NdB DyB and HoB discussed connection with cooperative Jahn-Teller effect due to CEF ground state degenerated quadrupolar moment. low temperature behavior Ce x La 1- B compounds is presented show Kondo on moment Γ 8 state. anomaly bulk modulus SmB related valence fluctuation system.
Magnetic susceptibility, magnetization process, specific heat, ultrasonic velocity, and inelastic neutron scattering experiments were performed on powdered single-crystalline ${\mathrm{TmAu}}_{2}$ samples. with a simple body-centered tetragonal ${\mathrm{MoSi}}_{2}$-type structure undergoes transition to an antiferromagnetic state at ${T}_{N}$ of 3.2 K. An anomaly 7.0 K is observed in the temperature dependence heat magnetic susceptibility. A very large softening beyond 50% from 300 down...
We measured the elastic and thermal properties to examine competing effect between intersite interactions Kondo coupling in Ce 0.75 La 0.25 B 6 0.6 0.4 with Γ 8 ground state. The huge softening of transverse C 44 mode both compounds at low temperatures indicates a remarkable fluctuation quadrupolar moments O y z , x 5 symmetry. In magnetic phase diagram we found new ordered IV addition antiferroquadrupolar II antiferromagnetic III. compound however, shows Fermi liquid state without...
The magnetic susceptibility, elastic constant, specific heat and magnetization of the semiconductor TmTe have been measured in detail. A phase transition which is likely to be an antiferro quadrupolar ordering was found occur at 1.8 K. measurements under fields along three main crystal axes revealed unusual characters this transition. ( H - T ) diagram below 5 very similar that CeB 6 . Above T, however, line for ∥[100] begins close toward =0 physical properties paramagnetic region high...
The magnetic and thermodynamic properties of metallic single-crystalline ${\mathrm{Gd}}_{3}{\mathrm{Ru}}_{4}{\mathrm{Al}}_{12}$, wherein Gd-Al layers with a distorted kagome lattice structure nonmagnetic Ru-Al are stacked alternately along the $c$ axis, have been reported. present investigation demonstrates gradual formation ferromagnetic trimers on decrease in temperature by Ruderman-Kittel-Kasuya-Yosida interaction. This may induce an effective transformation into antiferromagnetic...
We have studied the magnetic phase diagrams of dense Kondo compounds CeB 6 and Ce 0.5 La B by use low temperature ultrasonic measurements. A transition associated with a quadrupolar reorientation has clearly been observed around 1 kOe in antiferroquadrupolar II . In paramagnetic I crossover from ordinaly Γ 8 ground state to singlet found. The field induced antiferromagnetic III or found at critical 17 kOe. angle dependence diagram is also presented.
We have observed two gamma-ray transitions in (16)(Lambda)O from the 6.6 MeV excited 1(-)(2) state to both ground-state spin-doublet members (1(-)(1),0(-)) by (K-,pi(-)gamma) reaction. obtained doublet spacing be 26.4+/-1.6(stat)+/-0.5(syst) keV and excitation energy of 6561.7+/-1.1(stat)+/-1.7(syst) keV. The provides a small but nonzero strength tensor interaction between Lambda nucleon. This is first experimental result on LambdaN interaction.
We have simultaneously measured the energy spectra of neutrons and protons emitted in non-mesonic weak decays HeΛ5 CΛ12 hypernuclei produced via (π+,K+) reaction with much higher statistics than those previous experiments. The neutron-to-proton yield ratios for both at a high threshold (60 MeV) were approximately equal to two, which suggests that ratio neutron- proton-induced decay channels, Γn(Λn→nn)/Γp(Λp→np), is about 0.5. In neutron spectra, we found low-energy component unexpectedly...
In a γ-ray spectroscopy experiment with the (K−,π−) reaction on B10 target, we have observed 7/2+→5/2+ spin-flip M1 transition in Λ7Li via γ-γ coincidence 5/2+→1/2+E2 transition. This is first successful γ−γ measurement for hypernuclei. The measured energy 470.8±1.9(stat)±0.6(syst) keV. spacing of 7/2+,5/2+ doublet consistently explained using strengths spin-spin, Λ-spin-orbit, and tensor interactions obtained from previous γ-spectroscopy experiments.Received 3 December...
We performed a coincidence measurement of two nucleons emitted from the nonmesonic weak decay $_{\ensuremath{\Lambda}}^{5}\mathrm{He}$ formed via $^{6}\mathrm{Li}({\ensuremath{\pi}}^{+},{K}^{+})$ reaction. The energies and pair number distributions in opening angle between them were measured. In both $np$ $nn$ pairs, we observed clean back-to-back correlation coming two-body reactions $\ensuremath{\Lambda}p\ensuremath{\rightarrow}np$ $\ensuremath{\Lambda}n\ensuremath{\rightarrow}nn$,...
We have measured the angular correlation of pair nucleons np and nn emitted from nonmesonic weak decay (NMWD) ^{12}_{Lambda}C produced via (pi^+,K^+) reaction in coincidence measurement. The Lambda p -> n modes were clearly identified by measuring back-to-back nucleon pairs which is characteristic two-body kinematics. From numbers N_{nn} N_{np}, ratio Gamma_n/Gamma_p partial widths Gamma_n(Lambda nn) Gamma_p(Lambda np) was extracted to be 0.51+-0.13(stat) +- 0.05(syst); this result almost...
The bound-state level structures of the Λ16O and Λ15N hypernuclei were studied by γ-ray spectroscopy using a germanium detector array (Hyperball) via O16 (K−,π−γ) reaction. A scheme for was determined from observation three transitions doublet states (2−,1−) at ~6.7 MeV to ground-state (1−,0−). produced proton emission unbound in Λ16O. Three γ rays observed, lifetime 1/2+;1 state measured Doppler shift attenuation method. By comparing experimental results with shell-model calculations, spin...
We have measured the branching ratio of three-body process in nonmesonic weak decay Lambda12C to be 0.29+/-0.13. This result was obtained by reproducing nucleon and pair yields introducing a final state interaction. At same time, we determined absolute widths, Gamma(n) Gamma(p), along with Gamma2N, whose relative has been long-standing puzzle. Including process, successfully reproduced energy distribution, coincidence two-nucleon angular correlation, momentum sum distribution simultaneously.
We demonstrated extreme hole reduction and electron accumulation in YBa${}_{2}$Cu${}_{3}$O${}_{y}$ films by an electrochemical technique. Following the transition from superconductor to insulator, we succeeded doping electrons as evidenced decrease resistivity sign change of Hall coefficient. Further resulted metallic $n$-type with a carrier density \ensuremath{\sim}2.5 \ifmmode\times\else\texttimes\fi{} ${10}^{20}$ cm${}^{\ensuremath{-}3}$, but without any superconductivity. The oxygen...
In challenging a direct observation of the vacancy in crystalline silicon, we have carried out low-temperature ultrasonic measurements down to 20 mK. The longitudinal elastic constants non-doped and B-doped silicons, which were grown by floating zone (FZ) method commercial base, reveal softening proportional reciprocal temperature below K. applied magnetic fields turn FZ silicon temperature-independent behavior, while up 16 T do not affect silicon. We present plausible scenario for this...
We report magnetotransport properties of a two-dimensional electron gas confined at MgZnO/ZnO heterointerface in high magnetic field up to 26 T. High mobility and low charge carrier density enabled the observation fractional quantum Hall state nu = 1/3. For an even lower density, we observe transition from liquid insulator below filling factor Because large effective mass ZnO, suggest heterostructure be prototype system for highly correlated physics.
Successive magnetic phase transitions at T1 = 17.5 K and T2 18.5 in Gd3Ru4Al12, with a distorted kagome lattice of Gd ions, is studied using resonant X-ray diffraction polarization analysis. It has been suggested that this compound the S 7/2 spins on nearest-neighbor Gd-triangle form ferromagnetic trimer can be effectively considered as an antiferromagnetic triangular 21/2 spin trimers [S. Nakamura et al., Phys. Rev. B 98, 054410 (2018)]. We show order system described by incommensurate wave...