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Journal Articles

Direct measurement of the evolution of magnetism and superconductivity toward the quantum critical point

Higemoto, Wataru; Yokoyama, Makoto*; Ito, Takashi; Suzuki, Taiga*; Raymond, S.*; Yanase, Yoichi*

Proceedings of the National Academy of Sciences of the United States of America, 119(49), p.e2209549119_1 - e2209549119_6, 2022/11

 Times Cited Count:0 Percentile:0(Multidisciplinary Sciences)

no abstracts in English

Journal Articles

On the origin of localized electrons in SrTiO$$_3$$ metallized by hydrogen irradiation

Ito, Takashi

Meson, (56), p.21 - 26, 2022/09

no abstracts in English

Journal Articles

Hydrogen impurities in p-type semiconductors, GeS and GeTe

Nakamura, Jumpei*; Kawakita, Yukinobu; Shimomura, Koichiro*; Suemasu, Takashi*

Journal of Applied Physics, 130(19), p.195701_1 - 195701_7, 2021/11

 Times Cited Count:2 Percentile:7.86(Physics, Applied)

Journal Articles

Unveiling unconventional magnetism at the surface of Sr$$_2$$RuO$$_4$$

Fittipaldi, R.*; Hartmann, R.*; Mercaldo, M. T.*; Komori, Sachio*; Bj${o}$rlig, A.*; Higemoto, Wataru; Maeno, Yoshiteru*; Di Bernardo, A.*; 18 of others*

Nature Communications (Internet), 12, p.5792_1 - 5792_9, 2021/10

 Times Cited Count:11 Percentile:64.44(Multidisciplinary Sciences)

The layered oxide perovskite Sr$$_2$$RuO$$_4$$, which has been intensively investigated due to its unusual properties. Whilst the debate on the symmetry of the superconducting state in Sr$$_2$$RuO$$_4$$ is still ongoing, a deeper understanding of the Sr$$_2$$RuO$$_4$$ normal state appears crucial as this is the background in which electron pairing occurs. Here, by using low-energy muon spin spectroscopy we discover the existence of surface magnetism in Sr$$_2$$RuO$$_4$$ at an onset temperature higher than 50 K. Our observations set a reference for the discovery of the same magnetic phase in other materials.

Journal Articles

Dimensional reduction by geometrical frustration in a cubic antiferromagnet composed of tetrahedral clusters

Okuma, Ryutaro*; Kofu, Maiko; Asai, Shinichiro*; Avdeev, M.*; Koda, Akihiro*; Okabe, Hirotaka*; Hiraishi, Masatoshi*; Takeshita, Soshi*; Kojima, Kenji*; Kadono, Ryosuke*; et al.

Nature Communications (Internet), 12, p.4382_1 - 4382_7, 2021/07

 Times Cited Count:7 Percentile:61.42(Multidisciplinary Sciences)

Journal Articles

High-temperature antiferromagnetism in Yb based heavy fermion systems proximate to a Kondo insulator

Suzuki, Shintaro*; Takubo, Ko*; Kuga, Kentaro*; Higemoto, Wataru; Ito, Takashi; Tomita, Takahiro*; Shimura, Yasumichi*; Matsumoto, Yosuke*; Bareille, C.*; Wadachi, Hiroki*; et al.

Physical Review Research (Internet), 3(2), p.023140_1 - 023140_12, 2021/05

We report our experimental discovery of the transition temperature reaching 20 K in a Yb-based compound at ambient pressure. The Mn substitution at the Al site in an intermediate valence state of $$alpha$$-YbAlB$$_4$$ not only induces antiferromagnetic transition at a record high temperature of 20 K but also transforms the heavy-fermion liquid state in $$alpha$$-YbAlB$$_4$$ into a highly resistive metallic state proximate to a Kondo insulator.

Journal Articles

Pressure dependence of ferromagnetic phase boundary in BaVSe$$_3$$ studied with high-pressure $$mu^+$$SR

Sugiyama, Jun; Higemoto, Wataru; Andreica, D.*; Forslund, O. K.*; Nocerino, E.*; M${aa}$nsson, M.*; Sassa, Y.*; Gupta, R.*; Khasanov, R.*; Ota, Hiroto*; et al.

Physical Review B, 103(10), p.104418_1 - 104418_10, 2021/03

 Times Cited Count:8 Percentile:57.35(Materials Science, Multidisciplinary)

The magnetic nature of a quasi-one-dimensional compound, BaVSe$$_3$$, has been investigated with positive muon spin rotation and relaxation measurements at ambient and high pressures. At ambient pressure, the spectrum recorded under zero external magnetic field exhibited a clear oscillation below the Curie temperature due to the formation of quasistatic ferromagnetic order. As pressure increased from ambient pressure, $$T_{C}$$ was found to decrease slightly up to about 1.5 GPa, at which point $$T_{C}$$ started to increase rapidly with the further increase of the pressure. Based on a strong ferromagnetic interaction along the $$c$$-axis, the result revealed that there are two magnetic interactions in the ab-plane.

Journal Articles

High-temperature short-range order in Mn$$_3$$RhSi

Yamauchi, Hiroki; Sari, D. P.*; Watanabe, Isao*; Yasui, Yukio*; Chang, L.-J.*; Kondo, Keietsu; Ito, Takashi; Ishikado, Motoyuki*; Hagihara, Masato*; Frontzek, M. D.*; et al.

Communications Materials (Internet), 1, p.43_1 - 43_6, 2020/07

High-temperature short-range order is discovered up to 720 K in Mn$$_3$$RhSi by complementary use of neutron scattering and muon spin relaxation measurements.

Journal Articles

Gapless spin liquid in a square-kagome lattice antiferromagnet

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)

Journal Articles

Characterization and optimization of ultra slow muon beam at J-PARC/MUSE; A Simulation study

Pant, A. D.*; Higemoto, Wataru; Miyake, Yasuhiro; 8 of others*

Nuclear Instruments and Methods in Physics Research A, 929, p.129 - 133, 2019/06

 Times Cited Count:5 Percentile:48.99(Instruments & Instrumentation)

We have been developing an ultra slow muon microscope, at J-PARC. We performed Monte Carlo simulations, the results of which pointed out the significant effect of a stray magnetic field at the muonium chamber on the beam profile at sample position. To minimize this effect, we steered the beam using imbalance tuning of electric quadrupoles. This paper presents the simulation study of beam transportation, optimization, and characterization in terms of beam size, time, and energy distribution at sample position in one of the experimental areas, namely, U1A.

Journal Articles

Initial quantum levels of captured muons in CO, CO$$_2$$, and COS

Yoshida, Go*; Ninomiya, Kazuhiko*; Inagaki, Makoto*; Higemoto, Wataru; Strasser, P.*; Kawamura, Naritoshi*; Shimomura, Koichiro*; Miyake, Yasuhiro*; Miura, Taichi*; Kubo, Kenya*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 320, p.283 - 289, 2019/05

 Times Cited Count:4 Percentile:41.24(Chemistry, Analytical)

The role of valence electrons for the muon capture process by molecules is experimentally investigated with the aid of cascade calculations. Low-momentum muons are introduced to gas targets below atmospheric pressure. The initial states of captured muons are determined from the measured muonic X-ray structure of the Lyman and Balmer series. We propose that the lone pair electrons in the carbon atom of CO significantly contribute to the capture of a muon with large angular momenta.

Journal Articles

Nuclear magnetic field in solids detected with negative-muon spin rotation and relaxation

Sugiyama, Jun*; Umegaki, Izumi*; Nozaki, Hiroshi*; Higemoto, Wataru; Hamada, Koji*; Takeshita, Soshi*; Koda, Akihiro*; Shimomura, Koichiro*; Ninomiya, Kazuhiko*; Kubo, Kenya*

Physical Review Letters, 121(8), p.087202_1 - 087202_5, 2018/08

 Times Cited Count:18 Percentile:74.47(Physics, Multidisciplinary)

Journal Articles

Magnetic properties of one-dimensional quantum spin system Rb$$_2$$Cu$$_2$$Mo$$_3$$O$$_{12}$$ studied by muon spin relaxation

Kawamura, Seiko; Tomiyasu, Keisuke*; Koda, Akihiro*; Sari, D. P.*; Asih, R.*; Yoon, S.*; Watanabe, Isao*; Nakajima, Kenji

JPS Conference Proceedings (Internet), 21, p.011007_1 - 011007_5, 2018/03

Rb$$_2$$Cu$$_2$$Mo$$_3$$O$$_{12}$$ is a one-dimensional quantum spin system with spin frustration. The magnetic ground state of this system has been expected to be incommensurate spin-singlet from a theoretical study. Furthermore, it was recently reported that this system exhibited ferroelectricity under a magnetic field. We carried out $$mu$$SR studies on this system to understand the magnetic properties. A slow muon spin relaxation due to nuclear dipoles is observed in the whole measured temperatures ranging from 0.06 K to 250 K, indicating that no magnetic ordering. The result suggests that the system shows a spin-singlet ground state. Furthermore, it was found that the distribution of the internal magnetic field were slightly enhanced below 10 K. This temperature dependence resembles that of the electric polarization observed in the magnetic field. It may indicate that some local anomaly of charge/spin related to the ferroelectricity is detected by a microscopic probe.

Journal Articles

Introduction of particle transport code PHITS and analytical model for estimating the atmospheric cosmic-ray spectra PARMA

Abe, Shinichiro; Sato, Tatsuhiko

Meson, (47), p.34 - 39, 2018/03

Some researchers actively investigate secondary cosmic-ray muon radiography for imaging of large structures, detecting nuclear matter, and so on. The simulation is one of effective methods to estimate the required time for muon radiography or to optimize detection system. In this report, we introduce particle transport code PHITS and analytical model for estimating the atmospheric cosmic-ray spectra PARMA. Benchmark results are also shown. PHITS describes intensities of terrestrial muons in the ground well. PHITS also shows good agreement with measured data for particle generations from several interactions between muon and material. These results indicate the practicability of PHITS for simulation of muon radiography. PARMA reproduces cosmic-ray spectra on several spots well. Excellent agreement is seen between the measurements and PARMA for muon fluxes with large zenith angles and high energies, which are important for muon radiography.

Journal Articles

Depth-resolved measurements of current-induced spin accumulation in nonmagnetic metal thin films using ultra slow muon

Ito, Takashi; Higemoto, Wataru

KURRI-KR-202, p.42 - 45, 2015/03

no abstracts in English

Journal Articles

Present status of MLF building layout and ancillary facilities

Kaminaga, Masanori; Haga, Katsuhiro; Kinoshita, Hidetaka; Torii, Yoshikatsu; Hino, Ryutaro; Ikeda, Yujiro

Proceedings of ICANS-XVI, Volume 1, p.125 - 133, 2003/07

no abstracts in English

JAEA Reports

Accelerator technical design report for High-intensity Proton Accelerator Facility Projest, J-PARC

High-intensity Proton Accelerator Project Team

JAERI-Tech 2003-044, 788 Pages, 2003/03

JAERI-Tech-2003-044.pdf:47.31MB

This report presents the detail of the technical design of the acclerators for the High-Intensity Proton Accelerator Facility Project, J-PARC. The accelerator complex comprises a 400-MeV room-temperature linac (600-MeV superconducting linac), 3-GeV rapid-cycling synchrotron (RCS), and a 50-GeV synchrotron (MR). The 400-MeV beam is injected to the RCS, being accelerated to 3 GEV. The 1-MW beam thus produced is guided to the Materials Life Science Experimental Facility, with both the pulsed spallation neutron source and muon source. A part of the beam is transported to the MR, which provides the 0.75-MW beam to eithter the Nuclear and Fundamental Particle Experimental Facility or the Neutrino Production Target. On the other hand, the beam acclerated to 600 MeV by the superconducting linac is used for the Nuclear Waster Transmutation Experiment. In this way, this facility is unique, being multipurpose one, including many new inventions and Research and Development Results.

Journal Articles

Development of electrochemical hydrogen pump under vacuum condition for a compact tritium gas cycling system

Kato, Mineo; Ito, Takeshi*; Sugai, Hiroyuki; Kawamura, Yoshinori; Hayashi, Takumi; Nishi, Masataka; Tanase, Masakazu; Matsuzaki, Teiichiro*; Ishida, Katsuhiko*; Nagamine, Kanetada*

Fusion Science and Technology, 41(3), p.859 - 862, 2002/05

JAERI has a plane to develop a compact tritium gas recycling system for fusion research. This system is also very attractive for the muon-catalyzed fusion ($$mu$$CF) research at RIKEN-RAL Muon Facility in UK. For the research, JAERI has produced high purity tritium gas of 1,500 Ci and transported it to the Facility. In the $$mu$$CF experiments, the tritium gas was diluted by the deuterium in an optional concentration and the used tritium gas was carried back by the tritium transport container developed to JAERI. If it is possible to recycle the diluted tritium gas, i.e., the used tritium gas is enriched in the experimental site, the $$mu$$CF experiments should be conducted efficiently. rom the above point of view, in this paper, we propose the compact tritium gas recycling system based on the gas chromatography that has already developed in JAERI and a proton conductor.

JAEA Reports

Study of technical issues on proton beam line tunnel in material/life science experimental facility of high intensity proton accelerator project

Sakamoto, Shinichi; Meigo, Shinichiro; Konno, Chikara; Harada, Masahide; Miyake, Yasuhiro*; Kasugai, Yoshimi; Muto, Suguru*; Fujimori, Satoru*; Ono, Takehiro; Ikeda, Yujiro

JAERI-Tech 2001-075, 168 Pages, 2001/12

JAERI-Tech-2001-075.pdf:12.78MB

no abstracts in English

Journal Articles

High purity tritium gas supplied by JAERI for muon catalyzed fusion research at RIKEN-RAL muon facilty

Kato, Mineo; Kurosawa, Kiyoyuki; Sugai, Hiroyuki; Tanase, Masakazu; Matsuzaki, Teiichiro*; Ishida, Katsuhiko*; Nagamine, Kanetada*

KEK Proceedings 99-11, p.113 - 127, 1999/00

no abstracts in English

48 (Records 1-20 displayed on this page)