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

山内 宏樹; Sari, D. P.*; 渡邊 功雄*; 安井 幸夫*; Chang, L.-J.*; 近藤 啓悦; 伊藤 孝; 石角 元志*; 萩原 雅人*; Frontzek, M. D.*; et al.

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



Negatively charged muonium and related centers in solids

伊藤 孝; 髭本 亘; 下村 浩一郎*

Journal of the Physical Society of Japan, 89(5), p.051007_1 - 051007_8, 2020/05

 被引用回数:0 パーセンタイル:100(Physics, Multidisciplinary)

Muonium (Mu) centers formed upon implantation of $$mu^+$$ in a solid have long been investigated as an experimentally accessible model of isolated hydrogen impurities. Recent discoveries of hydridic centers formed at oxygen vacancies have stimulated a renewed interest in H$$^-$$ and corresponding Mu$$^-$$ centers in oxides. However, the two diamagnetic centers, Mu$$^+$$ and Mu$$^-$$, are difficult to separate spectroscopically. In this review article, we summarize established and developing methodologies for identifying Mu$$^-$$ centers in solids, and review recent Mu studies on said centers supposedly formed in mayenite, oxygen-deficient SrTiO$$_{3-x}$$, and BaTiO$$_{3-x}$$H$$_x$$ oxyhydride.


Controlled growth of boron-doped epitaxial graphene by thermal decomposition of a B$$_{4}$$C thin film

乗松 航*; 松田 啓太*; 寺澤 知潮; 高田 奈央*; 増森 淳史*; 伊藤 圭太*; 小田 晃司*; 伊藤 孝寛*; 遠藤 彰*; 舟橋 良次*; et al.

Nanotechnology, 31(14), p.145711_1 - 145711_7, 2020/04

 被引用回数:0 パーセンタイル:100(Nanoscience & Nanotechnology)

炭化珪素(SiC)基板上にエピタキシャル成長した炭化ホウ素(B$$_{4}$$C)薄膜の熱分解によって、ホウ素をドープしたエピタキシャルグラフェンが成長することを示した。SiC上のB$$_{4}$$CとB$$_{4}$$C上のグラフェンの界面は、一定の方位関係を持ち、ダングリングボンドのない安定した構造を局所的に持っていた。B$$_{4}$$Cの最初の炭素層はバッファー層として機能し、その上にグラフェンが積層していた。B$$_{4}$$C上のグラフェンは、ホウ素が高濃度にドープされており、正孔濃度は2$$times$$10$$^{13}$$ - 2$$times$$10$$^{15}$$ cm$$^{-2}$$の広い範囲で制御できた。高濃度にホウ素をドープしたグラフェンはスピングラス挙動を示し、これはスピンフラストレーションシステムにおける局所的な反強磁性秩序の存在を示唆している。炭化物の熱分解は、さまざまな用途向けの新しいの機能エピタキシャルグラフェンをウェーハスケールで得るための技術であると期待できる。


Polaronic nature of a muonium-related paramagnetic center in SrTiO$$_3$$

伊藤 孝; 髭本 亘; 幸田 章宏*; 下村 浩一郎*

Applied Physics Letters, 115(19), p.192103_1 - 192103_4, 2019/11

 被引用回数:2 パーセンタイル:42.97(Physics, Applied)

The hyperfine features and thermal stability of a muonium (Mu)-related paramagnetic center were investigated in the SrTiO$$_3$$ perovskite titanate via muon spin rotation spectroscopy. The hyperfine coupling tensor of the paramagnetic center was found to have prominent dipolar characteristics, indicating that the electron spin density is dominantly distributed on a Ti site to form a small polaron near an ionized Mu$$^+$$ donor. Based on a hydrogen-Mu analogy, interstitial hydrogen is also expected to form such a polaronic center in the dilute doping limit. The small activation energy of 30(3) meV found for the thermal dissociation of the Mu$$^+$$-polaron complex suggests that the strain energy required to distort the lattice is comparable to the electronic energy gained by localizing the electron.


Status of neutron spectrometers at J-PARC

梶本 亮一; 横尾 哲也*; 中村 充孝; 川北 至信; 松浦 直人*; 遠藤 仁*; 瀬戸 秀紀*; 伊藤 晋一*; 中島 健次; 河村 聖子

Physica B; Condensed Matter, 562, p.148 - 154, 2019/06

 被引用回数:1 パーセンタイル:67.64(Physics, Condensed Matter)

Seven time-of-flight quasielastic/inelastic neutron scattering instruments are installed on six beamlines in the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (JPARC). Four of these instruments are chopper-type direct-geometry spectrometers, one is a near-backscattering indirect-geometry spectrometer, and the other two are spin-echo-type spectrometers. This paper reviews the characteristic features, recent scientific outcomes, and progress in development of MLF spectrometers.


Recent results from the LHCf and RHICf experiments

伊藤 好孝*; 谷田 聖; 他30名*

EPJ Web of Conferences (Internet), 208, p.05004_1 - 05004_8, 2019/05

The Large Hadron Collider forward and the Relativistic Heavy Ion Collider forward experiments measured forward particles produced in high-energy hadron collisions at the LHC and RHIC. Using compact calorimeters neutral particles produced in pseudorapidities $$eta > 8.4$$ and $$eta > 6.0$$ are observed by the respective experiments. Because the collision energies ranging from 0.51 TeV to 13 TeV correspond to the cosmic-ray equivalent energies of $$10^{14}$$ to $$10^{17}$$ eV, the measurements are important to understand the hadronic interaction relevant to extensive air shower measurements. This paper reviews recent results of LHCf and initial performance of RHICf that took data in the 2017 RHIC operation.


Phase-transition kinetics of magnetic skyrmions investigated by stroboscopic small-angle neutron scattering

中島 多朗*; 稲村 泰弘; 伊藤 崇芳*; 大石 一城*; 大池 広志*; 賀川 史敬*; 吉川 明子*; 田口 康二郎*; 加倉井 和久*; 十倉 好紀*; et al.

Physical Review B, 98(1), p.014424_1 - 014424_5, 2018/07

 被引用回数:4 パーセンタイル:58.39(Materials Science, Multidisciplinary)



Proceedings of the MLF User Group Meeting on Direct Geometry Spectrometers (DIRECTION 2017); October 16-17, 2017, Ibaraki Quantum Beam Research Center (Tokai, Ibaraki, Japan)

梶本 亮一; 横尾 哲也*; 蒲沢 和也*; 中村 充孝; 河村 聖子; 伊藤 晋一*; 中島 健次

JAEA-Review 2017-031, 107 Pages, 2018/02


平成29年10月16日$$sim$$17日の2日間にわたり、いばらき量子ビーム研究センターにおいて、J-PARC物質・生命科学実験施設(MLF)の4台の直接配置型(チョッパー型)中性子分光器合同のユーザーミーティング「DIRECTION 2017」が開催された。4台の装置とは4SEASONS (BL01), HRC (BL12), AMATERAS (BL14), POLANO (BL23)であり、本ミーティングはこれらの装置におけるユーザー利用の活性化に向けて、J-PARC MLF, 高エネルギー加速器研究機構物質構造科学研究所, 総合科学研究機構の共催で開催されたものである。本ミーティングでは各装置、試料環境、ソフトウェアの最新状況に加え、各装置における最近の実験およびデータ解析の例が幅広い研究分野にわたって紹介された。本報告書はこのミーティングの講演要旨および講演で使用された発表資料を収録したものである。


Neutron scattering study of yttrium iron garnet

社本 真一; 伊藤 孝; 大西 弘明; 山内 宏樹; 稲村 泰弘; 松浦 直人*; 赤津 光洋*; 樹神 克明; 中尾 朗子*; 茂吉 武人*; et al.

Physical Review B, 97(5), p.054429_1 - 054429_9, 2018/02

 被引用回数:5 パーセンタイル:48.81(Materials Science, Multidisciplinary)



Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex, 2; Neutron scattering instruments

中島 健次; 川北 至信; 伊藤 晋一*; 阿部 淳*; 相澤 一也; 青木 裕之; 遠藤 仁*; 藤田 全基*; 舟越 賢一*; Gong, W.*; et al.

Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12



New precise measurement of muonium hyperfine structure interval at J-PARC

上野 恭裕*; 青木 正治*; 深尾 祥紀*; 東 芳隆*; 樋口 嵩*; 飯沼 裕美*; 池戸 豊*; 石田 啓一*; 伊藤 孝; 岩崎 雅彦*; et al.

Hyperfine Interactions, 238(1), p.14_1 - 14_6, 2017/11

 被引用回数:2 パーセンタイル:12.39

MuSEUM is an international collaboration aiming at a new precise measurement of the muonium hyperfine structure at J-PARC (Japan Proton Accelerator Research Complex). Utilizing its intense pulsed muon beam, we expect a ten-fold improvement for both measurements at high magnetic field and zero magnetic field. We have developed a sophisticated monitoring system, including a beam profile monitor to measure the 3D distribution of muonium atoms to suppress the systematic uncertainty.


Turbulent transport reduction induced by transition on radial electric field shear and curvature through amplitude and cross-phase in torus plasma

小林 達哉*; 伊藤 公孝*; 井戸 毅*; 神谷 健作*; 伊藤 早苗*; 三浦 幸俊; 永島 芳彦*; 藤澤 彰英*; 稲垣 滋*; 居田 克巳*

Scientific Reports (Internet), 7(1), p.14971_1 - 14971_8, 2017/11

 被引用回数:12 パーセンタイル:17.33(Multidisciplinary Sciences)

Spatiotemporal evolutions of radial electric field and turbulence are measured simultaneously in the H-mode transition, which is a prototypical example of turbulence structure formation in high-temperature plasmas. In the dynamical phase where transport barrier is established abruptly, the time-space-frequency-resolved turbulent particle flux is obtained. Here we report the validation of the mechanism of transport barrier formation quantitatively. It is found that the particle flux is suppressed predominantly by reducing density fluctuation amplitude and cross phase between density fluctuation and potential fluctuation. Both radial electric field shear and curvature are responsible for the amplitude suppression as was predicted by theory. Turbulence amplitude reduction immediately responds to the growth of the radial electric field non-uniformity and saturates, while cross phase continuously approaches zero.


Reduction and resource recycling of high-level radioactive wastes through nuclear transmutation; Isolation techniques of Pd, Zr, Se and Cs in simulated high level radioactive waste using solvent extraction

佐々木 祐二; 森田 圭介; 伊藤 圭祐; 鈴木 伸一; 塩飽 秀啓; 高橋 優也*; 金子 昌章*; 大森 孝*; 浅野 和仁*

Proceedings of International Nuclear Fuel Cycle Conference (GLOBAL 2017) (USB Flash Drive), 4 Pages, 2017/09

高レベル廃液中のPd, Zr, Se, Csは長半減期核種のPd-107, Zr-93, Se-79, Cs-135を有している。高レベル廃液から除去し、核変換により処分することで、環境負荷低減に役立てることができる。これら元素について、PdはMIDOA, NTAアミド、Csはクラウンエーテル、ZrはTODGA, HDEHP, Seはフェニレンジアミンで抽出可能である。それぞれ元素の回収条件について検討した成果について述べる。


Materials and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex, 3; Neutron devices and computational and sample environments

坂佐井 馨; 佐藤 節夫*; 瀬谷 智洋*; 中村 龍也; 藤 健太郎; 山岸 秀志*; 曽山 和彦; 山崎 大; 丸山 龍治; 奥 隆之; et al.

Quantum Beam Science (Internet), 1(2), p.10_1 - 10_35, 2017/09



Spin wave dispersion just above the magnetic order-order transition in the metallic antiferromagnet Mn$$_{3}$$Pt

井深 壮史*; 横尾 哲也*; 伊藤 晋一*; 蒲沢 和也*; 中村 充孝; 今井 基晴*

Journal of Physics; Conference Series, 868(1), p.012017_1 - 012017_6, 2017/07



Fine dispersion of Pt$$_{4-5}$$ subnanoclusters and Pt single atoms over porous carbon supports and their structural analyses with X-ray absorption spectroscopy

糸井 弘行*; 西原 洋知*; 小林 俊介*; Ittisanronnachai, S.*; 石井 孝文*; Berenguer, R.*; 伊藤 仁*; 松村 大樹; 京谷 隆*

Journal of Physical Chemistry C, 121(14), p.7892 - 7902, 2017/04

 被引用回数:17 パーセンタイル:23.36(Chemistry, Physical)

We demonstrate the fine dispersion of Pt$$_{4-5}$$ subnanoclusters or Pt single atoms on two types of porous carbon supports, Ketjen black (KB) and zeolite-templated carbon (ZTC). For the fine dispersion of Pt subnanoclusters, simply filling an organoplatinum complex, (COD)PtMe$$_{2}$$, as a Pt precursor into the micropores is found to be crucial to prevent agglomeration or sintering of Pt subnanoclusters. Moreover, it is possible to disperse Pt single atoms on ZTC, simply by decreasing the Pt loading amount down to ca. 0.9 wt%, owing to some stabilization effect by oxygen-containing functional groups. Extended X-ray absorption fine structure (EXAFS) analysis for Pt subnanoclusters reveals that the Pt-Pt bond is contracting to a large extent ($$sim$$2.8%) relative to balk values, and upon hydrogen chemisorption, the bond elongates more than the reported values for the 1.0 nm sized Pt nanoparticles.


Development of prototype reactor maintenance, 1; Application to piping system of sodium-cooled reactor prototype

小竹 庄司*; 近澤 佳隆; 高屋 茂; 大高 雅彦; 久保 重信; 荒井 眞伸; 桾木 孝介; 伊藤 隆哉*; 山口 彰*

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 6 Pages, 2017/04



Development of prototype reactor maintenance, 2; Application to piping support of sodium-cooled reactor prototype

荒井 眞伸; 桾木 孝介; 相澤 康介; 近澤 佳隆; 高屋 茂; 久保 重信; 小竹 庄司*; 伊藤 隆哉*; 山口 彰*

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 6 Pages, 2017/04




佐藤 稔紀; 笹本 広; 石井 英一; 松岡 稔幸; 早野 明; 宮川 和也; 藤田 朝雄*; 棚井 憲治; 中山 雅; 武田 匡樹; et al.

JAEA-Research 2016-025, 313 Pages, 2017/03




Uniaxial pressure effect on the magnetic ordered moment and transition temperatures in BaFe$$_{2-x}$$T$$_{x}$$As$$_{2}$$ ($$T$$ = Co,Ni)

Tam, D. M.*; Song, Y.*; Man, H.*; Cheung, S. C.*; Yin, Z.*; Lu, X.*; Wang, W.*; Frandsen, B. A.*; Liu, L.*; Gong, Z.*; et al.

Physical Review B, 95(6), p.060505_1 - 060505_6, 2017/02

 被引用回数:11 パーセンタイル:27.21(Materials Science, Multidisciplinary)

We use neutron diffraction and muon spin relaxation to study the effect of in-plane uniaxial pressure on the antiferromagnetic (AF) orthorhombic phase in BaFe$$_{2-x}$$T$$_{x}$$As$$_{2}$$ and its Co- and Ni-substituted members near optimal superconductivity. In the low-temperature AF ordered state, uniaxial pressure necessary to detwin the orthorhombic crystals also increases the magnetic ordered moment, reaching an 11% increase under 40 MPa for BaFe$$_{1.9}$$Co$$_{0.1}$$As$$_2$$, and a 15% increase for BaFe$$_{1.915}$$Ni$$_{0.085}$$As$$_2$$. We also observe an increase of the AF ordering temperature ($$T_N$$) of about 0.25 K/MPa in all compounds, consistent with density functional theory calculations that reveal better Fermi surface nesting for itinerant electrons under uniaxial pressure. The doping dependence of the magnetic ordered moment is captured by combining dynamical mean field theory with density functional theory, suggesting that the pressure-induced moment increase near optimal superconductivity is closely related to quantum fluctuations and the nearby electronic nematic phase.

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