Tamatsukuri, Hiromu; Hasegawa, Takumi*; Sagayama, Hajime*; Mizumaki, Masaichiro*; Murakami, Yoichi*; Kajitani, Joe*; Higashinaka, Ryuji*; Matsuda, Tatsuma*; Aoki, Yuji*; Tsutsui, Satoshi*
Physical Review B, 107(2), p.024303_1 - 024303_8, 2023/01
Horibe, Yoichi*; Mori, Shigeo*; Ikeda, Naoshi*; Yoshii, Kenji; Maeno, Hiroshi*; Murakami, Yasukazu*
Ferroelectrics, 584(1), p.20 - 30, 2021/00
Temperature dependence of charge-ordered crystal structures and domain structures in RFeO (R: Y and Lu) was investigated by energy-filtered transmission electron microscopy, combined with conventional transmission electron microscopy. The presence of three-dimensional to two-dimensional charge ordering transition were observed in both RFeO on heating. Furthermore, real-space images obtained with the energy-filtered transmission electron microscopy revealed that YRFeO has less anisotropic nanometer-scale charge-ordered domains than LuRFeO. These findings in RFeO indicate the importance of the interchange interactions between Fe-O bilayers in addition to those within bilayers in the structural phase transitions associated with charge ordering in this system.
Tamatsukuri, Hiromu; Murakami, Yoichi*; Kuramoto, Yoshio*; Sagayama, Hajime*; Matsuura, Masato*; Kawakita, Yukinobu; Matsuishi, Satoru*; Washio, Yasuhito*; Inoshita, Takeshi*; Hamada, Noriaki*; et al.
Physical Review B, 102(22), p.224406_1 - 224406_5, 2020/12
Yamaura, Junichi*; Hiraka, Haruhiro*; Iimura, Soshi*; Muraba, Yoshinori*; Bang, J.*; Ikeuchi, Kazuhiko*; Nakamura, Mitsutaka; Inamura, Yasuhiro; Honda, Takashi*; Hiraishi, Masatoshi*; et al.
Physical Review B, 99(22), p.220505_1 - 220505_6, 2019/06
Inelastic neutron scattering was performed for an iron-based superconductor, where most of D (deuterium) replaces oxygen, while a tiny amount goes into interstitial sites. By first-principle calculation, we characterize the interstitial sites for D (and for H slightly mixed) with four equivalent potential minima. Below the superconducting transition temperature Tc = 26 K, new excitations emerge in the range 5-15 meV, while they are absent in the reference system LaFeAsOF. The strong excitations at 14.5 meV and 11.1 meV broaden rapidly around 15 K and 20 K, respectively, where each energy becomes comparable to twice of the superconducting gap. The strong excitations are ascribed to a quantum rattling, or a band motion of hydrogen, which arises only if the number of potential minima is larger than two.
Tamatsukuri, Hiromu*; Hiraka, Haruhiro*; Ikeuchi, Kazuhiko*; Iimura, Soshi*; Muraba, Yoshinori*; Nakamura, Mitsutaka; Sagayama, Hajime*; Yamaura, Junichi*; Murakami, Yoichi*; Kuramoto, Yoshio*; et al.
Physical Review B, 98(17), p.174415_1 - 174415_6, 2018/11
Magnetic excitations in a heavily electron-doped antiferromagnet, LaFeAsOD, have been investigated using powder inelastic neutron scattering. Unlike other parent compounds of the iron-based superconductors, the magnetic excitation gap in LaFeAsOD was not detected down to the lowest measured temperature of 4 K. This result can be understood as a result of quasi-isotropy within the ab plane, which is consistent with the band calculation result that the orbital plays the dominant role in the magnetism of LaFeAsOH. In addition, the intensities of the magnetic excitations in this phase are much stronger than those in nondoped LaFeAsO. Even in the paramagnetic phase, the magnetic excitation in LaFeAsOD persists. These results corroborate recent studies showing that the electron doping enhances the localized nature in this system.
Yoshida, Masahiro*; Ishii, Kenji; Naka, Makoto*; Ishihara, Sumio*; Jarrige, I.*; Ikeuchi, Kazuhiko*; Murakami, Yoichi*; Kudo, Kazutaka*; Koike, Yoji*; Nagata, Tomoko*; et al.
Scientific Reports (Internet), 6, p.23611_1 - 23611_8, 2016/03
Kubota, Masato; Yamada, Hiroyuki*; Nakao, Hironori*; Okamoto, Jun*; Yamasaki, Yuichi*; Sawa, Akihito*; Murakami, Yoichi*
Japanese Journal of Applied Physics, 53(5S1), p.05FH07_1 - 05FH07_5, 2014/05
Okamoto, Jun*; Nakao, Hironori*; Yamasaki, Yuichi*; Wadachi, Hiroki*; Tanaka, Arata*; Kubota, Masato; Horigane, Kazumasa*; Murakami, Yoichi*; Yamada, Kazuyoshi*
Journal of the Physical Society of Japan, 83(4), p.044705_1 - 044705_6, 2014/04
Hiraishi, Masatoshi*; Iimura, Soshi*; Kojima, Kenji*; Yamaura, Junichi*; Hiraka, Haruhiro*; Ikeda, Kazutaka*; Miao, P.*; Ishikawa, Yoshihisa*; Torii, Shuki*; Miyazaki, Masanori*; et al.
Nature Physics, 10(4), p.300 - 303, 2014/04
Asai, Shinichiro*; Okazaki, Ryuji*; Terasaki, Ichiro*; Yasui, Yukio*; Kobayashi, Wataru*; Nakao, Akiko*; Kobayashi, Kensuke*; Kumai, Reiji*; Nakao, Hironori*; Murakami, Yoichi*; et al.
Journal of the Physical Society of Japan, 82(11), p.114606_1 - 114606_6, 2013/11
Neutron and synchrotron X-ray diffraction for LaCo RhO have been carried out in order to investigate the structural properties related with the spin state of Co ions. We have found that the values of the Co(Rh)-O bond lengths in the Co(Rh)O octahedron of LaCoRhO are nearly identical at 10 K. The lattice volume for the Rh substituted samples decreases with the thermal expansion coefficient similar to that of LaCoO from room temperature, and ceases to decrease around 70 K. These experimental results favor a mixed state consisting of the high-spin state and low-spin state Co ions, and suggest that the high-spin state Co ions are thermally excited in addition to those pinned by the substituted Rh ions.
Nakajima, Nakako*; Brunton, H.*; Watanabe, Ritsuko; Shrikhande, A.*; Hirayama, Ryoichi*; Matsufuji, Naruhiro*; Fujimori, Akira*; Murakami, Takeshi*; Okayasu, Ryuichi*; Jeggo, P.*; et al.
PLOS ONE (Internet), 8(8), p.e70107_1 - e70107_14, 2013/08
Heavy particle irradiation can produce complex DNA double strand breaks (DSBs) within the particle trajectory. Additionally, secondary electrons, termed delta-electrons, can create low linear energy transfer (LET) damage distant from the track. Using imaging with deconvolution, we show that at 8 hours after exposure to Fe ions, H2AX foci forming at DSBs within the particle track are large and encompass multiple smaller and closely localised foci, which we designate as clustered H2AX foci. We also identified simple H2AX foci distant from the track. They are rapidly repaired. Clustered H2AX foci induced by heavy particle radiation cause prolonged checkpoint arrest compared to simple H2AX foci. However, mitotic entry was observed when 10 clustered foci remain. Thus, cells can progress into mitosis with multiple clusters of DSBs following the traversal of a heavy particle.
Ishii, Kenji; Jarrige, I.*; Yoshida, Masahiro*; Ikeuchi, Kazuhiko*; Inami, Toshiya; Murakami, Yoichi*; Mizuki, Junichiro
Journal of Electron Spectroscopy and Related Phenomena, 188, p.127 - 132, 2013/06
Ohgama, Kazuya; Ando, Yoko; Yamaguchi, Mika; Ikuta, Yuko; Shinohara, Nobuo; Murakami, Hiroyuki; Yamashita, Kiyonobu; Uesaka, Mitsuru*; Demachi, Kazuyuki*; Komiyama, Ryoichi*; et al.
JAEA-Review 2013-004, 76 Pages, 2013/05
JAEA together with the Japan Nuclear Human Resource Development Network (JN-HRD Net), the University of Tokyo (UT) and the Japan Atomic Industrial Forum (JAIF) cohosted the IAEA-Nuclear Energy Management School in Tokai Village, aiming that Japan will be the center of nuclear HRD in the Asian region. In the school, not only lectures by IAEA experts, but also lectures by Japanese experts and technical visits were included for foreign participants. The school contributed to the internationalization of Japanese young professionals, development of nuclear human resource of other countries, and enhancement of cooperation between IAEA and Japan. Additionally, collaborative relationship within JN-HRD Net was strengthened by the school. In this report, findings obtained during the preparatory work and the school period are reported for future international nuclear HRD activities in Japan.
Nakayama, Masashi; Amano, Kenji; Tokiwa, Tetsuya; Yamamoto, Yoichi; Oyama, Takuya; Amano, Yuki; Murakami, Hiroaki; Inagaki, Daisuke; Tsusaka, Kimikazu; Kondo, Keiji; et al.
JAEA-Review 2012-035, 63 Pages, 2012/09
The Horonobe Underground Research Laboratory Project is planned to extend over a period 20 years. The investigations will be conducted in three phases, namely "Phase 1: Surface-based investigations", "Phase 2: Construction Phase" (investigations during construction of the underground facilities) and "Phase 3: Operation phase"(research in the underground facilities). This report summarizes the results of the investigations for the 2011 fiscal year (2011/2012). The investigations, which are composed of "Geoscientific research" and "R&D on geological disposal technology", were carried out according to "Horonobe Underground Research Laboratory Project Investigation Program for the 2011 Fiscal year". The results of these investigations, along with the results which were obtained in other departments of Japan Atomic Energy Agency (JAEA), are properly offered to the implementations and the safety regulations. For the sake of this, JAEA has proceeded with the project in collaboration with experts from domestic and overseas research organisations.
Taguchi, Yasujiro*; Sakai, Hideaki*; Okuyama, Daisuke*; Ishiwata, Shintaro*; Fujioka, Jun*; Fukuda, Tatsuo; Hashizume, Daisuke*; Kagawa, Fumitaka*; Takahashi, Yoichiro*; Shimano, Ryo*; et al.
Physica B; Condensed Matter, 407(11), p.1685 - 1688, 2012/06
Amano, Yuki; Yamamoto, Yoichi; Nanjo, Isao; Murakami, Hiroaki; Yokota, Hideharu; Yamazaki, Masanori; Kunimaru, Takanori; Oyama, Takahiro*; Iwatsuki, Teruki
JAEA-Data/Code 2011-023, 312 Pages, 2012/02
In the Horonobe Underground Research Laboratory (URL) Project, ground water from boreholes, river water and precipitation have been analyzed for the environmental monitoring since the fiscal year 2001. This report shows the data set of water chemistry since the fiscal year 2001 to the fiscal year 2010.
Bizen, Daisuke*; Nakao, Hironori*; Iwasa, Kazuaki*; Murakami, Yoichi*; Osakabe, Toyotaka; Fujioka, Jun*; Yasue, Toshio*; Miyasaka, Shigeki*; Tokura, Yoshinori*
Journal of the Physical Society of Japan, 81(2), p.024715_1 - 024715_6, 2012/02
The magnetic phase diagrams for VO ( = Y, Tb) were determined by low temperature and high pressure neutron-diffraction techniques. We found that the magnetic ground state in TbVO changes from -type spin ordering (-SO) to -type spin ordering (-SO) on application of pressure. The transition of the magnetic ground state also indicates that the ground state of the orbital ordering changes from -type orbital ordering (-OO) to -type orbital ordering (-OO). In YVO, the -SO and -OO phases set in simultaneously up to 6.2 GPa, and the disorder-[-SO, -OO] phase transition appears above 6 GPa. This is the first observation of a simultaneous spin and orbital order-disorder phase transition in perovskite-type transition-metal oxides MO. The [-SO, -OO] phase is strongly stabilized with increasing pressure, and both the covalency effect and the superexchange interaction play roles in this stabilization.
Ishii, Kenji; Ishihara, Sumio*; Murakami, Yoichi*; Ikeuchi, Kazuhiko*; Kuzushita, Kaori*; Inami, Toshiya; Owada, Kenji; Yoshida, Masahiro; Jarrige, I.; Tatami, Naka*; et al.
Physical Review B, 83(24), p.241101_1 - 241101_4, 2011/06
Yoshida, Masahiro; Ishii, Kenji; Ikeuchi, Kazuhiko*; Jarrige, I.; Murakami, Yoichi*; Mizuki, Junichiro; Tsutsui, Kenji; Toyama, Takami*; Maekawa, Sadamichi*; Kudo, Kazutaka*; et al.
Physica C, 470(Suppl.1), p.S145 - S146, 2010/12
Nakao, Hironori*; Owada, Kenji; Shimomura, Susumu*; Ochiai, Akira*; Namikawa, Kazumichi*; Mizuki, Junichiro; Mimura, Hidekazu*; Yamauchi, Kazuto*; Murakami, Yoichi*
AIP Conference Proceedings 1234, p.935 - 938, 2010/06