A5077660395- Semiconductor Quantum Structures and Devices
- Quantum and electron transport phenomena
- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Multiferroics and related materials
- ZnO doping and properties
- GaN-based semiconductor devices and materials
- Chalcogenide Semiconductor Thin Films
- Advanced Semiconductor Detectors and Materials
- Spacecraft and Cryogenic Technologies
- Solid-state spectroscopy and crystallography
- Electronic and Structural Properties of Oxides
- Organic and Molecular Conductors Research
- Quantum Dots Synthesis And Properties
- Planetary Science and Exploration
- Rare-earth and actinide compounds
- Ferroelectric and Piezoelectric Materials
- Magnetism in coordination complexes
- Cold Atom Physics and Bose-Einstein Condensates
- Iron-based superconductors research
- Advanced Chemical Physics Studies
- Quantum, superfluid, helium dynamics
- Diamond and Carbon-based Materials Research
- Graphene research and applications
National Institute for Materials Science
2014-2024
Tokyo University of Science
2016-2019
Hokkaido University
2019
Osaka Kyoiku University
2007
University of Cambridge
2003-2004
Independent Administrative Institution National Research Institute for Cultural Properties
2001
Institute of Metal Research
2000
The University of Tokyo
1992-1998
University of Nottingham
1995
A novel design of white light emitting diodes (WLEDs) emerges to meet the growing global demand for resource sustainability while preserving health and environment. To achieve this goal, a facile method is developed chemical synthesis luminescent silicon nanocrystal (ncSi) with large Stokes shift between absorption emission. The WLED prepared by simple spin‐coating method, contains hybrid‐bilayer ncSi polymer in its device active region. Interestingly, well‐controlled ultrathin layer on...
Polarized optical reflectivity spectra of untwinned ${\mathrm{PrBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ are reported. The show a large ab-plane anisotropy in the infrared region with higher along chain direction. For polarization, spectrum is similar to that deoxygenated tetragonal ${\mathrm{PrBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathit{y}}$, an energy gap about 1.5 eV, indicating it difficult dope holes into ${\mathrm{CuO}}_{2}$ planes by addition...
To elucidate the underlying nature of hidden order (HO) state in heavy-fermion compound ${\mathrm{URu}}_{2}{\mathrm{Si}}_{2}$, we measure electrical transport properties ultraclean crystals a high field, low temperature regime. Unlike previous studies, present system with much less impurity scattering resolves distinct anomaly Hall resistivity at ${H}^{*}=22.5\text{ }\text{ }\mathrm{T}$, well below destruction field HO phase $\ensuremath{\simeq}36\text{ }\mathrm{T}$. In addition, novel...
Stimulated by strong demand for thermal expansion control from advanced modern industries, various giant negative (NTE) materials have been developed during the last decade. Nevertheless, most such exhibit anisotropic in crystal lattice. Therefore, strains and cracks induced repeated cycling degrade their performance as thermal-expansion compensators. Here we achieved isotropic NTE with volume change exceeding 3%, up to 4.1%, via of electronic configuration Sm atoms SmS, (4 f)6 or f)5(5d)1,...
Organic alloys λ-(BETS) 2 Fe x Ga 1- Cl 4 show superconductivity only under very high magnetic fields parallel to the conducting layer for ≥0.47. As decreases, field induced superconducting phase shifts towards lower and a striking field-induced insulator superconductor transition is observed below T =0.45. We that overall features of global diagram are well understood in terms Jaccarino-Peter compensation mechanism. These results provide new road map future design superconductors.
Through magnetic linear dichroism spectroscopy, the susceptibility anisotropy of metallic single-walled carbon nanotubes has been extracted and found to be 2-4 times greater than values for semiconducting nanotubes. This large can understood in terms orbital paramagnetism arising from Aharonov-Bohm-phase-induced gap opening a parallel field, our calculations quantitatively reproduce these results. We also compare with previous work nanotubes, which confirm that does not increase linearly...
Abstract Since the discovery of Verwey transition in magnetite, metal compounds with pyrochlore structures have been intensively studied as a platform for realizing remarkable electronic phase transitions. We report on that preserves cubic symmetry β-pyrochlore oxide CsW 2 O 6 , where each W 5 d electrons are confined regular-triangle 3 trimers. This trimer formation represents self-organization electrons, which can be resolved into charge order satisfying Anderson condition nontrivial way,...
A scheme for calculating quasiparticle effective masses beyond the standard local-density approximation is presented. Correlation effects are included in form of self-energy correction which leads to two important factors. The first factor arises from energy dependence resulting renormalization and second originates wave-vector self-energy. We demonstrate feasibility our approach by some wide-gap semiconductors AlN, GaN, ZnO, artificial ${\mathrm{AlGaN}}_{2},$ well known their technological...
We have performed dielectric measurements and neutron diffraction experiments on the double perovskite ${\text{In}}_{2}{\text{NiMnO}}_{6}$. A ferroelectric polarization, $P\ensuremath{\simeq}30\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{C}/{\mathrm{m}}^{2},$ is observed in a polycrystalline sample below ${T}_{N}=$ 26 K where magnetic phase transition occurs. The experiment demonstrates that complex noncollinear structure with ``cycloidal'' ``proper screw'' components appears ${T}_{N}$,...
We synthesize PbMn7O12 perovskite under high-pressure (6 GPa) and high-temperature (1373 K) conditions investigate its structural, magnetic, dielectric, ferroelectric properties. find that exhibits rich physical properties from interplay among charge, orbital, spin degrees of freedom structural crystallizes in space group R3̅ near room temperature shows a phase transition at TCO = 397 K to cubic structure Im3̅; the Im3̅-to-R3̅ is associated with charge ordering. Below TOO 294 K, modulation...
TlMO(3) perovskites (M(3+) = transition metals) are exceptional members of trivalent perovskite families because the strong covalency Tl(3+)-O bonds. Here we report on synthesis, crystal structure and properties TlCrO(3) investigated by Mössbauer spectroscopy, specific heat, dc/ac magnetization dielectric measurements. is prepared under high pressure (6 GPa) temperature (1500 K) conditions. The refined using synchrotron X-ray powder diffraction data: space group Pnma (no. 62), Z 4 lattice...
We have observed cyclotron resonance and impurity (1s-2${\mathit{p}}^{+}$ transition) in a wide far-infrared wavelength range between 9.27 70.5 \ensuremath{\mu}m under pulsed high magnetic fields up to 180 T. A very large resonant polaron effect reflecting electron-phonon coupling constant was both resonances, as well nonparabolicity. The experimental results of were found be good agreement with theoretical calculation based on the Wigner-Brillouin second-order perturbation theory taking...
The valence fluctuations of Sm in samarium monosulfide (SmS) are known to induce possible large isotropic negative thermal expansion (NTE), but difficulty crystal growth prevents establishment the NTE function. For this study, we prepared Ce-doped and Nd-doped SmS polycrystalline samples using a simpler method with much lower reaction temperature than existing method. Typically, Sm0.80Ce0.20S exhibits giant total volume change 2.6% wide range from 330 K 100 K, lowest covered here....
Cyclotron resonance (CR) measurements for the Fe-based superconductor KFe(2)As(2) are performed. One signal CR is observed, and attributed to two-dimensional α Fermi surface at Γ point. We found a large discrepancy in effective masses of [(3.4±0.05)m(e) (m(e) free-electron mass)] de Haas-van Alphen results, direct evidence mass enhancement due electronic correlation. A comparison results shows that both intra- interband correlations contribute KFe(2)As(2).
We have applied the modified droplet epitaxy method using sulfur termination to fabricate InAs quantum dots on GaAs(001) substrates for first time. It is observed that S-terminated surface effectively prevents two-dimensional growth of InAs, forming nanocrystals. From magneto-photoluminescence measurements this structure, three-dimensional confinement effect was confirmed. This promising fabrication dots, not only in lattice-matched system but also lattice-mismatched system.
We have observed cyclotron resonance in the infrared wavelength range between 10.6 and 16.9 \ensuremath{\mu}m with pulsed high magnetic fields up to 220 T. The band-edge mass of n-type ZnS is ${\mathit{m}}^{\mathrm{*}}$=0.20\ifmmode\pm\else\textpm\fi{}0.01${\mathit{m}}_{0}$ Fr\"ohlich electron-phonon coupling constant \ensuremath{\alpha} 0.63 from a comparison experimental results theoretical calculation based on Wigner-Brillouin second-order perturbation theory. also phonon-assisted at...
Abstract Cyclotron resonance has been observed in ZnO heterostructures with dense two dimensional electron gas at a wide range of the sub‐millimeter wave up to 651 GHz. The typical carrier concentration sample is found be higher than 10 12 cm –2 from Shubnikov de Haas oscillation measurement, and quantum Hall effect also high magnetic fields 25 T. effective mass system just determined as m* = 0.32 ± 0.01 m 0 field dependence cyclotron experiments. obtained enhanced comparison bare three...
Electrical-field-induced insulator-to-metal (I-to-M) transition of samarium monosulfides was investigated systematically. Experiment results demonstrate that Sm0.9Ca0.1S undergoes the I-to-M when in a small electric field 250 V/cm at liquid-nitrogen temperatures. However, simultaneous measurement I–V characteristics and strain did not detect electrical-field-induced expected from large volume contraction originating valence Sm. Mid-infrared to visible region reflectivity spectroscopy...
In a ferroelectric helimagnetic phase of spin-driven multiferroic, ${\mathrm{CuFeO}}_{2}$, we find irreversibly additive evolution electric polarization $P$ induced by sweeping magnetic field $H$ under an applied $E$, despite large coercive in the phase. From unpolarized neutron diffraction experiments with situ measurements reveal that increment is achieved variation incommensurate modulation wave number $q$ helical ordering regardless increasing or decreasing $H$. Combining this result...
We report the magnetic structure and anisotropy of quasi-one-dimensional $S=\frac{1}{2}$ antiferromagnet ${\mathrm{Na}}_{2}{\mathrm{CuSO}}_{4}{\mathrm{Cl}}_{2}$ obtained by single-crystal neutron scattering, electron spin resonance (ESR), magnetization measurements, following an earlier study its dynamics [M. Fujihala et al., Phys. Rev. B 101, 024410 (2020)]. A N\'eel-type is formed within chain this compound, where spins point along $b$ axis, ESR data indicate antisymmetric exchange with a...