Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Hirota, Yuki*; Tominaga, Taiki*; Kawabata, Takashi*; Kawakita, Yukinobu; Matsuo, Yasumitsu*
Bioengineering (Internet), 10(5), p.622_1 - 622_17, 2023/05
Times Cited Count：0 Percentile：0.01(Biotechnology & Applied Microbiology)Hashimoto, Shunsuke*; Yamaguchi, Satoshi*; Harada, Masashi*; Nakajima, Kenji; Kikuchi, Tatsuya*; Oishi, Kazuki*
Journal of Colloid and Interface Science, 638, p.475 - 486, 2023/05
Times Cited Count：2 Percentile：66.51(Chemistry, Physical)Recently, it has been reported that anomalous improvement in the thermal conductivity of nanofluid composed of base liquids and dispersed solid nanoparticles, compared to the theoretically predicted value calculated from the particle fraction. Generally, the thermal conductivity values of gases and liquids are dominated by the mean free path of the molecules during translational motion. Herein, we present solid evidence showing the possible contribution of the vibrational behavior of liquid molecules around nanoparticles to increasing these thermal conductivities.
dynamics in the H conductors LaH
O
Tamatsukuri, Hiromu; Fukui, Keiga*; Iimura, Soshi*; Honda, Takashi*; Tada, Tomofumi*; Murakami, Yoichi*; Yamaura, Junichi*; Kuramoto, Yoshio*; Sagayama, Hajime*; Yamada, Takeshi*; et al.
Physical Review B, 107(18), p.184114_1 - 184114_8, 2023/05
Times Cited Count：0 Percentile：0(Materials Science, Multidisciplinary)
H
OFujihara, Masayoshi; Hagihara, Masato; Morita, Katsuhiro*; Murai, Naoki; Koda, Akihiro*; Okabe, Hirotaka*; Mitsuda, Setsuo*
Physical Review B, 107(5), p.054435_1 - 054435_8, 2023/02
Times Cited Count：0 Percentile：0(Materials Science, Multidisciplinary)The 
= 1/2 Heisenberg linear chain antiferromagnet is the simplest spin model; nevertheless it serves as a platform for various quantum many-body phenomena. Here, we report the magnetic behavior of a quasi-one-dimensional antiferromagnet KCuPOHO. A long-range commensurate antiferromagnetic order with ordered moment 0.31(1) 
per spin occurs at 
= 11.7(1) K. Above , the inelastic neutron excitation is characterized by a two spinon continuum. The intrachain interaction 
and interchain interaction 
are estimated to be 172 K and 4.25(4) K, respectively; thus the ratio of the / = 0.0247(3). At lower energies, below , a spin gap is observed in the dispersive excitations. These results are consistent with characteristics observed in weakly interacting = 1/2 Heisenberg chain system.
Nakajima, Kenji; Kikuchi, Tatsuya*; Kawamura, Seiko; Kambara, Wataru*
EPJ Web of Conferences, 272, p.02012_1 - 02012_8, 2022/11
We will present some of attempts on AMATEAS, a cold-neutron chopper spectrometer at a pulsed source, to increase time-windows at a single-measurement condition. One of ways is that, by allowing interveined trajectories on the time-of-flight diagram, the usable width selectable for 
is can be increased. Based on our experiences, the conditions of pulse repetition rate multiplication based polychromatic 
measurements on chopper spectrometers at pulsed sources will be discussed. Optimization of wide-band polychromatic measurements and a generalized formulated condition will be proposed. Application of our idea to existing spectrometers and to the criteria design of an optimized chopper spectrometer will be also discussed with suggesting further possibility to improve efficiency by modifying the pulse shaping chopper.
Hirota, Yuki*; Tominaga, Taiki*; Kawabata, Takashi*; Kawakita, Yukinobu; Matsuo, Yasumitsu*
Bioengineering (Internet), 9(10), p.599_1 - 599_17, 2022/10
Times Cited Count：2 Percentile：34.67(Biotechnology & Applied Microbiology)
and TiH
up to 21 GPa by incoherent inelastic neutron scatteringHattori, Takanori; Nakamura, Mitsutaka; Iida, Kazuki*; Machida, Akihiko*; Sano, Asami; Machida, Shinichi*; Arima, Hiroshi*; Oshita, Hidetoshi*; Honda, Takashi*; Ikeda, Kazutaka*; et al.
Physical Review B, 106(13), p.134309_1 - 134309_9, 2022/10
Times Cited Count：0 Percentile：0(Materials Science, Multidisciplinary)Hydrogen vibration excitations of fluorite-type ZrH and TiH were investigated up to 21 GPa and 4 GPa, respectively, by incoherent inelastic neutron scattering experiments. The first excitation energies increased with pressure, as described by the equations 
(meV) = 141.4(2) + 1.02(2)
(GPa) and (meV) = 149.4(1) + 1.21(8)(GPa) for ZrH and TiH, respectively. Coupling with pressure dependence of lattice parameters, the relations between metal-hydrogen distance (
) and are found to be well described by the equations (meV) = 1.62(9)
10
(
(meV) = 1.47(21) 10 
(AA), respectively. The slopes of these curves are much steep compared to the previously reported trend in various fluorite-type metal hydrides at ambient pressure. The hydrogen wave function spreading showed that the local potential field for a hydrogen atom shrinks more intensively than the tetrahedral site. These behavior is likely caused by the rigid metal ion core and the resulting confinement of the hydrogen atom in the narrower potential field at high pressures.
Al
and Nd
Pd
Ge
Metoki, Naoto; Shibata, Kaoru; Matsuura, Masato*; Kitazawa, Hideaki*; Suzuki, Hiroyuki*; Yamauchi, Hiroki; Hagihara, Masato; Frontzek, M. D.*; Matsuda, Masaaki*
Journal of the Physical Society of Japan, 91(5), p.054710_1 - 054710_6, 2022/05
Times Cited Count：0 Percentile：0(Physics, Multidisciplinary)Hyperfine splitting of Nd nuclei in NdPdAl has been studied by means of high-resolution neutron spectroscopy. We observed inelastic peaks at 
eV coming from the hyperfine splitting in the magnetically ordered phase due to the hyperfine interactions between Nd nuclei (
=7/2) and the 4
electrons with 
ground state composed of mainly 
. At very low temperatures, nuclear spin of Nd is polarized with increasing occupation probability of low energy levels and contributes to the enhancement of the antiferromagnetic Bragg intensities: the elastic non-spin-flip channel is dominant. As an application of this phenomenon, we determined the Nd moment and hyperfine splitting from the temperature dependence of an antiferromagnetic Bragg intensities for NdPdGe.
Furuike, Yoshihiko*; Ouyang, D.*; Tominaga, Taiki*; Matsuo, Tatsuhito*; Mukaiyama, Atsushi*; Kawakita, Yukinobu; Fujiwara, Satoru*; Akiyama, Shuji*
Communications Physics (Internet), 5(1), p.75_1 - 75_12, 2022/04
Times Cited Count：4 Percentile：67.44(Physics, Multidisciplinary)Yang, J.*; Ren, W.*; Zhao, X.*; Kikuchi, Tatsuya*; Miao, P.*; Nakajima, Kenji; Li, B.*; Zhang, Z.*
Journal of Materials Science & Technology, 99, p.55 - 60, 2022/02
Times Cited Count：6 Percentile：41.35(Materials Science, Multidisciplinary)High-entropy alloys are characteristic of extensive atomic occupational disorder on high-symmetric lattices, differing from traditional alloys. Here, we investigate magnetic and thermal transport properties of the prototype face-centered-cubic high-entropy alloy CrMnFeCoNi by combining physical properties measurements and neutron scattering. Direct-current (dc) and alternating-current (ac) magnetizations measurements indicate a mictomagnetic behavior with coexisting antiferromagnetic and ferromagnetic interactions in the entire temperature region and three anomalies are found at about 80, 50, and 20 K, which are related to the paramagnetic to antiferromagnetic transition, the antiferromagnetic to ferromagnetic transition, and the spin freezing, respectively. The electrical and thermal conductivities are significantly reduced compared to Ni and the temperature dependence of lattice thermal conductivity exhibits a glass-like plateau. Inelastic neutron scattering measurements suggest weak anharmonicity so that the thermal transport is expected to be dominated by the defect scattering.
Hattori, Takanori; Kawamura, Seiko; Kawasaki, Takuro
High Pressure Research, 42(2), p.226 - 235, 2022/00
Times Cited Count：0 Percentile：0(Physics, Multidisciplinary)We have developed a hybrid piston cylinder cell for quasi-elastic neutron scattering (QENS) experiments up to about 1 GPa. It consists of a fretted cylinder made of the high tensile steel (SNCM439) liner and the Al alloy (NA700) jacket. Performance tests revealed that the cell can withstand a pressure of 0.8 GPa without irreversible damage and has 4.4 times larger neutron transmission at 3.14 meV (5.10
in wavelength) than that of a conventional CuBe monobloc cylinder. Combined with the sample assembly devised for suppressing multiple scattering, high quality QENS spectra of water were obtained up to 0.8 GPa. This study illustrates the efficacy of the hybrid cylinders not only for increasing maximum available pressure but also manipulating the available pressure and the signal intensity, depending on the purpose of the experiments.
Tominaga, Taiki*; Sahara, Masae*; Kawakita, Yukinobu; Nakagawa, Hiroshi; Yamada, Takeshi*
Journal of Applied Crystallography, 54(6), p.1631 - 1640, 2021/12
Times Cited Count：4 Percentile：55.82(Chemistry, Multidisciplinary)
Li
TiO
(x = 0.13) studied by quasielastic neutron scatteringMatsuura, Masato*; Fujiwara, Yasuyuki*; Moriwake, Hiroki*; Ohara, Koji*; Kawakita, Yukinobu
Physical Review B, 104(9), p.094305_1 - 094305_7, 2021/09
Times Cited Count：5 Percentile：44.86(Materials Science, Multidisciplinary)Kawakita, Yukinobu; Kikuchi, Tatsuya*; Tahara, Shuta*; Nakamura, Mitsutaka; Inamura, Yasuhiro; Maruyama, Kenji*; Yamauchi, Yasuhiro*; Kawamura, Seiko; Nakajima, Kenji
JPS Conference Proceedings (Internet), 33, p.011071_1 - 011071_6, 2021/03
CuI is a well-known superionic conductor in a high temperature solid phase where the mobile cations migrate between interstitial sites in the f.c.c. sublattice formed by iodine ions. Even in the molten state, it shows several features suggesting collective or cooperative ionic motion. MD results show that Cu diffuses much faster than I. The Cu-Cu partial structure factor have a FSDP which indicates a medium-range ordering of Cu ions. Moreover the Cu-Cu partial pair distribution deeply penetrates into the nearest neighboring Cu-I shell. To reveal origin such anomalous behaviors of molten CuI, we performed quaiselastic neutron scattering (QENS) by the disk-chopper spectrometer AMATERAS at MLF, J-PARC. To interpret the total dynamic structure factor obtained from coherent QENS, the mode distribution analysis was applied. It is found that the motion of iodine is a kind of fluctuating within an almost local area while Cu ions diffuse much faster than iodine ions.
anisotropic triangular antiferromagnet CaReO
ClNawa, Kazuhiro*; Hirai, Daigoro*; Kofu, Maiko; Nakajima, Kenji; Murasaki, Ryo*; Kogane, Satoshi*; Kimata, Motoi*; Nojiri, Hiroyuki*; Hiroi, Zenji*; Sato, Taku*
Physical Review Research (Internet), 2(4), p.043121_1 - 043121_11, 2020/12
The spin excitations of the = anisotropic triangular antiferromagnet CaReOCl were investigated by inelastic neutron-scattering experiments. The spin excitation spectrum exhibits sharp dispersive modes in addition to a spinonlike continuum. The consistency with the simulated spectrum based on the random-phase approximation is better for CaReOCl than for CsCuCl, indicating that the spin system in the former remains closer to a Tomonaga-Luttinger liquidlike disordered state.
Kojima, Seiji*; Novikov, V. N.*; Kofu, Maiko; Yamamuro, Osamu*
Physica Status Solidi (B), 257(11), p.2000073_1 - 2000073_6, 2020/11
Times Cited Count：3 Percentile：19.68(Physics, Condensed Matter)Takahashi, Yoshiyuki*; Koizumi, Mitsuo
Nihon Genshiryoku Gakkai-Shi ATOMO
, 62(8), p.452 - 456, 2020/08
no abstracts in English
-electron states of NpPdAl and the isostructural family; Heavy fermion superconductivity accompanied by valence crossoverMetoki, Naoto
Kotai Butsuri, 55(7), p.285 - 296, 2020/07
Electron states are the main theme of "solid-state physics", which is essential for microscopic understanding of multipoles and superconductivity, etc. Rare earths (4) and actinides (5) provide variety of interesting states realized with competing interactions between the increasing number of electrons. Since crystal field splitting of many-body electron system is smaller than the bandwidth, (1) high resolution experiments are needed, (2) essentially no clear spectrum with well defined peaks is expected in itinerant Ce and U compounds, and (3) Np and Pu is strictly regulated. Therefore, systematic research on magnetic excitations by neutron scattering experiments of localized compounds and rare earth iso-structural reference is useful. We describe the electron states of heavy electron compounds NpPd
Al and actinide and rare earth based iso-structural family.
Fujihara, Masayoshi*; Morita, Katsuhiro*; Mole, R.*; Mitsuda, Setsuo*; Toyama, Takami*; Yano, Shinichiro*; Yu, D.*; Sota, Shigetoshi*; Kuwai, Tomohiko*; Koda, Akihiro*; et al.
Nature Communications (Internet), 11, p.3429_1 - 3429_7, 2020/07
Times Cited Count：39 Percentile：90.63(Multidisciplinary Sciences)OAllenspach, S.*; Biffin, A.*; Stuhr, U.*; Tucker, G. S.*; Kawamura, Seiko; Kofu, Maiko; Voneshen, D. J.*; Boehm, M.*; Normand, B.*; Laflorencie, N.*; et al.
Physical Review Letters, 124(17), p.177205_1 - 177205_7, 2020/05
Times Cited Count：10 Percentile：65.11(Physics, Multidisciplinary)
