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Zhu, M.*; Romerio, V.*; Steiger, N.*; Nabi, S. D.*; Murai, Naoki; Kawamura, Seiko; Povarov, K. Y.*; Skourski, Y.*; Sibille, R.*; Keller, L.*; et al.
Physical Review Letters, 133(18), p.186704_1 - 186704_6, 2024/11
Times Cited Count:9 Percentile:91.73(Physics, Multidisciplinary)Nirei, Masami; Kofu, Maiko; Nakajima, Kenji; Kikuchi, Tatsuya*; Kawamura, Seiko; Murai, Naoki; Harada, Masahide; Inamura, Yasuhiro
Journal of Neutron Research, 26(2-3), p.75 - 82, 2024/09
Gu, Y. Q.*; Gu, Y. M.*; Liu, F.*; Kawamura, Seiko; Murai, Naoki; Zhao, J.*
Physical Review Letters, 132(24), p.246702_1 - 246702_7, 2024/06
Times Cited Count:2 Percentile:64.46(Physics, Multidisciplinary)Nagl, J.*; Flavin, D.*; Hayashida, S.*; Povarov, K. Y.*; Yan, M.*; Murai, Naoki; Kawamura, Seiko; Simutis, F.*; Hicken, T. J.*; Luetkens, H.*; et al.
Physical Review Research (Internet), 6(2), p.023267_1 - 023267_18, 2024/06
Kofu, Maiko; Kawamura, Seiko; Murai, Naoki; Ishii, Rieko*; Hirai, Daigoro*; Arima, Hiroshi*; Funakoshi, Kenichi*
Physical Review Research (Internet), 6(1), p.013006_1 - 013006_9, 2024/01
Shangguan, Y.*; Bao, S.*; Dong, Z.-Y.*; Xi, N.*; Gao, Y.-P.*; Ma, Z.*; Wang, W.*; Qi, Z.*; Zhang, S.*; Huang, Z.*; et al.
Nature Physics, 19(12), p.1883 - 1889, 2023/09
Times Cited Count:19 Percentile:93.50(Physics, Multidisciplinary)Ishii, Yui*; Yamamoto, Arisa*; Sato, Naoki*; Nambu, Yusuke*; Kawamura, Seiko; Murai, Naoki; Ohara, Koji*; Kawaguchi, Shogo*; Mori, Takao*; Mori, Shigeo*
Physical Review B, 106(13), p.134111_1 - 134111_7, 2022/10
Times Cited Count:0 Percentile:0.00(Materials Science, Multidisciplinary)Kawamura, Hideyuki; Hirose, Naoki*; Nakayama, Tomoharu*; Ito, Toshimichi
JAEA-Data/Code 2021-004, 34 Pages, 2021/05
The Japan Atomic Energy Agency measured the ocean current across the Tsugaru Strait using an Acoustic Doppler Current Profiler attached on a ferryboat from October 1999 to January 2008. The characteristics of the ocean current in the Tsugaru Strait must be understood for predicting oceanic dispersion of radioactive materials released from nuclear facilities around the strait. Furthermore, it is critical to elucidate the mechanism of the Tsugaru Warm Current from an oceanography viewpoint. The dataset obtained in this investigation consists of daily ocean current data files that record the components of the current speed in the east-west and north-south directions from the surface layer to the bottom layer. The dataset stores 2,211 daily ocean current data files, despite some data periods missing from October 1999 to January 2008. In this study, information on the dataset is described for users to analyze the dataset properly for their purposes. Section 1 provides the background and purpose of the ocean current measurement, Section 2 explains the methodology of measurement using an Acoustic Doppler Current Profiler, and Section 3 explains the record format of the daily ocean current data files and data acquisition rate and presents analysis results. Finally, Section 4 concludes this study.
Nakajima, Kenji; Kawamura, Seiko; Kofu, Maiko; Murai, Naoki; Inamura, Yasuhiro; Kikuchi, Tatsuya*; Wakai, Daisuke*
JPS Conference Proceedings (Internet), 33, p.011089_1 - 011089_7, 2021/03
The recent update of AMATERAS, a cold-neutron disk-chopper spectrometer at Japan Proton Accelerator Research Complex (J-PARC), is reported. AMATERAS has been operating for a decade. Since 2017, some updates have been done or are underway, which include installing new detectors, replacing the vacuum system of the scattering chamber, and other works. We are also working on the re-investigation of the resolution function. Demonstration measurements were carried out at 1MW test operations done in 2018 and 2019. Plans of upgrading the spectrometer are currently being considered.
Iida, Kazuki*; Yoshida, Hiroyuki*; Nakao, Akiko*; Jeschke, H. O.*; Iqbal, Y.*; Nakajima, Kenji; Kawamura, Seiko; Munakata, Koji*; Inamura, Yasuhiro; Murai, Naoki; et al.
Physical Review B, 101(22), p.220408_1 - 220408_6, 2020/06
Times Cited Count:28 Percentile:79.78(Materials Science, Multidisciplinary)Crystal and magnetic structures of the mineral centennialite CaCu(OD)
Cl
0.6D
O are investigated by means of synchrotron X-ray diffraction and neutron diffraction measurements complemented by density functional theory (DFT) and pseudofermion functional renormalization group (PFFRG) calculations. In CaCu
(OD)
Cl
0.6D
O, Cu
ions form a geometrically perfect kagome network with antiferromagnetic
. No intersite disorder between Cu
and Ca
ions is detected. CaCu
(OD)
Cl
0.6D
O enters a magnetic long-range ordered state below
= 7.2 K, and the
=0 magnetic structure with negative vector spin chirality is obtained. The ordered moment at 0.3 K is suppressed to 0.58(2)
B. Our DFT calculations indicate the presence of antiferromagnetic
and ferromagnetic
superexchange couplings of a strength which places the system at the crossroads of three magnetic orders (at the classical level) and a spin-
PFFRG analysis shows a dominance of
=0 type magnetic correlations, consistent with and indicating proximity to the observed
=0 spin structure. The results suggest that this material is located close to a quantum critical point and is a good realization of a
-
-
kagome antiferromagnet.
Iida, Kazuki*; Kofu, Maiko; Suzuki, Katsuhiro*; Murai, Naoki; Kawamura, Seiko; Kajimoto, Ryoichi; Inamura, Yasuhiro; Ishikado, Motoyuki*; Hasegawa, Shunsuke*; Masuda, Takatsugu*; et al.
Journal of the Physical Society of Japan, 89(5), p.053702_1 - 053702_5, 2020/05
Times Cited Count:23 Percentile:78.59(Physics, Multidisciplinary)Murai, Naoki; Fukuda, Tatsuo; Nakajima, Masamichi*; Kawamura, Mitsuaki*; Ishikawa, Daisuke*; Tajima, Setsuko*; Baron, A. Q. R.*
Physical Review B, 101(3), p.035126_1 - 035126_6, 2020/01
Times Cited Count:7 Percentile:34.47(Materials Science, Multidisciplinary)We report an inelastic X-ray scattering investigation of phonons in FeSe superconductor. Comparing the experimental phonon dispersion with density functional theory (DFT) calculations in the non-magnetic state, we found a significant disagreement between them. A better overall agreement was obtained by allowing for spin-polarization in DFT calculations, despite the absence of magnetic order in FeSe. This calculation gives a realistic approximation, at DFT level, of the disordered paramagnetic state of FeSe, in which strong spin fluctuations are present.
Kajimoto, Ryoichi; Ishikado, Motoyuki*; Kira, Hiroshi*; Kaneko, Koji; Nakamura, Mitsutaka; Kamazawa, Kazuya*; Inamura, Yasuhiro; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Murai, Naoki; et al.
Physica B; Condensed Matter, 556, p.26 - 30, 2019/03
Times Cited Count:3 Percentile:13.18(Physics, Condensed Matter)Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Ishikado, Motoyuki*; Murai, Naoki; Kira, Hiroshi*; Nakatani, Takeshi; et al.
Journal of Physics; Conference Series, 1021(1), p.012030_1 - 012030_6, 2018/06
Times Cited Count:3 Percentile:85.11(Nuclear Science & Technology)Sakuma, Hiroshi*; Tachi, Yukio; Yotsuji, Kenji; Suehara, Shigeru*; Arima, Tatsumi*; Fujii, Naoki*; Kawamura, Katsuyuki*; Honda, Akira
Clays and Clay Minerals, 65(4), p.252 - 272, 2017/08
Times Cited Count:2 Percentile:15.19(Chemistry, Physical)Structure and stability of montmorillonite edge faces (110), (010), (100), and (130) of the layer charges y = 0.5 and 0.33 are investigated by the first-principles electronic calculations based on the density functional theory. Stacking and single layer models are tested for understanding the effect of stacking on the stability of montmorillonite edge faces. Most stacking layers stabilize the edge faces by making hydrogen bonds between the layers; therefore, the surface energy of stacking layers is reduced rather than the single layer model. This indicates that the surface energy of edge faces should be estimated depending on the swelling conditions. Lowest surface energies of (010) and (130) edge faces were realized by the presence of Mg ions on the edge faces. These edge faces have a strong adsorption site for cations due to local negative charge of the edges.
Ishimatsu, Naoki*; Sata,Yusuke*; Maruyama, Hiroshi*; Watanuki, Tetsu; Kawamura, Naomi*; Mizumaki, Masaichiro*; Irifune, Tetsuo*; Sumiya, Hitoshi*
Hoshako, 28(1), p.3 - 11, 2015/01
no abstracts in English
Azuma, Masaki*; Chen, W.*; Seki, Hayato*; Czapski, M.*; Olga, S.*; Oka, Kengo*; Mizumaki, Masaichiro*; Watanuki, Tetsu; Ishimatsu, Naoki*; Kawamura, Naomi*; et al.
Nature Communications (Internet), 2, p.347_1 - 347_5, 2011/06
Times Cited Count:397 Percentile:99.15(Multidisciplinary Sciences)no abstracts in English
Kawamura, Hideyuki; Ito, Toshimichi; Kobayashi, Takuya; Otosaka, Shigeyoshi; Hirose, Naoki*; Togawa, Orihiko
Journal of Oceanography, 66(5), p.649 - 662, 2010/10
Times Cited Count:2 Percentile:5.84(Oceanography)A numerical experiment is performed to reproduce a distribution of concentrations of Sr and
Cs and estimate their total amounts in the Japan Sea. The concentrations of
Sr and
Cs in the surface layer is in the range of 1.0-1.5 Bq/m
and 2.0-2.5 Bq/m
. The concentrations in the intermediate and deep layer are higher than those observed in the northwestern Pacific Ocean, indicating active winter convection in the Japan Sea. The total amounts of
Sr and
Cs in the seawater is evaluated to be 1.34 PBq (1 PBq = 10
Bq) and 2.02 PBq, which demonstrates an estimation by observational data in the Japan Sea expeditions between 1997 and 2002 by Japan Atomic Energy Agency. The total amounts of
Sr and
Cs vary corresponding to deposition at the sea surface with the maximums of 4.86 PBq for
Sr and 7.33 PBq for
Cs in the mid-1960s.
Kawamura, Hideyuki; Ito, Toshimichi; Kobayashi, Takuya; Otosaka, Shigeyoshi; Hirose, Naoki*; Togawa, Orihiko
Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 4 Pages, 2010/10
This study aims to demonstrate many findings in the Japan Sea expeditions by Japan Atomic Energy Agency between 1997 and 2002 making use of an ocean general circulation model. A numerical experiment is performed between 1945 and 2000 with deposition at the sea surface by global fallout as main source of anthropogenic radionuclides. The concentrations of Sr and
Cs in the surface layer are approximately in the range of 1.0-1.5 Bq/m
and 2.0-2.5 Bq/m
and they exponentially decrease with depth from the sea surface to the sea bottom. Total amounts of
Sr and
Cs in the seawater of the Japan Sea are estimated to be about 1.34 PBq (1 PBq = 10
Bq) and 2.02 PBq in the numerical experiment, which demonstrates observational estimations in the Japan Sea expeditions. Time series of the total amounts show that they attain the maximums of 4.86 PBq for
Sr and 7.33 PBq for
Cs in 1964.
Ishimatsu, Naoki*; Sasada, Ryohei*; Maruyama, Hiroshi*; Ichikawa, Takayuki*; Miyaoka, Hiroki*; Kimura, Toru*; Tsubota, Masami*; Kojima, Yoshitsugu*; Tsumuraya, Takao*; Oguchi, Tamio*; et al.
Journal of Physics; Conference Series, 190, p.012070_1 - 012070_4, 2009/11
Times Cited Count:5 Percentile:78.54(Physics, Condensed Matter)We have investigated the effect of hydrogenation on La and
electronic states in metallic LaH
by X-ray absorption near edge structure at the La
-edges. As the hydrogen content
increases from 0 to 2.6, white-line intensity at the La
-edges shows a remarkable increase in the range of
2.0. This is interpreted as the increase in La
hole induced by interstitial H atoms on the octahedral sites. On the other hand, the shoulder structure at the La
-edge disappears in the process of
= 0.0
2.0, indicating that the
-
hybridization is weakened by H atoms on the tetrahedral sites. This study demonstrates that H atoms on the two interstitial H sites provide different contribution to the modification of the electronic states.