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藤原 理賀; 萩原 雅人; 幸田 章宏*; 中村 惇平*; 松尾 晶*; 金道 浩一*; 石角 元志*
Physical Review Materials (Internet), 9(1), p.014406_1 - 014406_9, 2025/01
被引用回数:0 パーセンタイル:0.00(Materials Science, Multidisciplinary)We reported the magnetic behavior of a rhombic lattice quantum antiferromagnet KCoPOH
O. The rhombic lattice model is equivalent to a model of a square lattice with two different diagonal components, and competing exchange interactions potentially produce exotic quantum states. This compound is well characterized by the
= 1/2 state. The magnetic structure of KCoPO
H
O is identified as an incommensurate helical structure, characterized by a magnetic modulation propagation vector
= (0.1747(1) 0 0) with an in-plane moment rotating along the
axis. Moreover, a magnetic field-induced phase transition is observed at approximately 1 T. The application of a magnetic field suppresses spin ordering and enhance spin fluctuations. Our experimental results suggest the presence of a quantum phase in the magnetic phase diagram of the spin-1/2 Heisenberg rhombic lattice antiferromagnet with easy-plane anisotropy.
石角 元志*; 高橋 竜太*; 山内 康弘*; 中村 雅俊*; 石丸 宙*; 山内 沙羅*; 河村 聖子; 吉良 弘*; 坂口 佳史*; 渡辺 真朗; et al.
JPS Conference Proceedings (Internet), 41, p.011010_1 - 011010_7, 2024/05
Recent status of cryogenic sample environment equipment at the Materials and Life Science Experimental Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC) has been reported. We have reviewed the specifications and performance of cryogenic sample environment equipment and a newly installed Gifford-McMahon (GM) cryofurnace, which are mainly managed by the Cryogenic and Magnet group in the sample environment team at the MLF. Moreover, the recent maintenance and update of each piece of equipment, the improved temperature-control function, and the expansion of the usable beamline of the cryogenic sample environment equipment are described.
奥平 琢也*; 中部 倫太郎*; Auton, C. J.*; 遠藤 駿典; 藤岡 宏之*; Gudkov, V.*; 井出 郁央*; 猪野 隆*; 石角 元志*; 神原 理*; et al.
Physical Review C, 109(4), p.044606_1 - 044606_9, 2024/04
被引用回数:0 パーセンタイル:0.00(Physics, Nuclear)We measured the spin dependence in a neutron-induced p-wave resonance by using a polarized epithermal neutron beam and a polarized nuclear target. Our study focuses on the 0.75 eV -wave resonance state of
La+n, where largely enhanced parity violation has been observed. We determined the partial neutron width of the
-wave resonance by measuring the spin dependence of the neutron absorption cross section between polarized
La and polarized neutrons. Our findings serve as a foundation for the quantitative study of the enhancement effect of the discrete symmetry violations caused by mixing between partial amplitudes in the compound nuclei.
中部 倫太郎*; Auton, C. J.*; 遠藤 駿典; 藤岡 宏之*; Gudkov, V.*; 広田 克也*; 井出 郁央*; 猪野 隆*; 石角 元志*; 神原 理*; et al.
Physical Review C, 109(4), p.L041602_1 - L041602_4, 2024/04
被引用回数:0 パーセンタイル:0.00(Physics, Nuclear)Neutron transmission experiments can offer a new type of highly sensitive search for time-reversal invariance violating (TRIV) effects in nucleon-nucleon interactions via the same enhancement mechanism observed for large parity violating (PV) effects in neutron-induced compound nuclear processes. In these compound processes, the TRIV cross-section is given as the product of the PV cross-section, a spin-factor , and a ratio of TRIV and PV matrix elements. We determined
to be 0.59
0.05 for
La+n using both (n,
) spectroscopy and (
+
) transmission. This result quantifies for the first time the high sensitivity of the
La 0.75 eV
-wave resonance in a future search for
-odd/
-odd interactions in (
+
) forward transmission.
長谷美 宏幸; 高橋 竜太*; 山内 康弘*; 石角 元志*; 河村 聖子; 小峰 良太
JPS Conference Proceedings (Internet), 41, p.011003_1 - 011003_5, 2024/03
The instrument control software framework "IROHA2" is used for the neutron and muon experiments at J-PARC MLF. IROHA2 consists of four core software components: i) The device control server controls and monitors devices, ii) the instrument management server authenticates users, manages measurements and configures device combinations, iii) the sequence management server builds and controls automatic measurements, iv) the integrate control server has centralized control over the device monitoring and measurement. Since IROHA2 is equipped with a web user interface, the control system can be accessed remotely using a web browser. MLF's sample environment team developed several device modules of the device control server in order to be able to use the sample environment equipment for automatic measurements. For example, the modules currently used in the experiments are those for He and
He cryostats, superconducting magnets, niobium furnaces, and so on. In this presentation, we will introduce the features of IROHA2 and the functions of the device modules for the sample environment equipment.
下田 愛海*; 岩佐 和晃*; 桑原 慶太郎*; 佐賀山 基*; 中尾 裕則*; 石角 元志*; 大原 高志; 中尾 朗子*; 星川 晃範*; 石垣 徹*
JPS Conference Proceedings (Internet), 38, p.011091_1 - 011091_6, 2023/05
Synchrotron X-ray diffraction study revealed that NdSn
(
= Rh and Ir) undergo structural phase transitions characterized by the wave vector
=(1/2,1/2,0). Neutron diffraction study revealed antiferromagnetic ordering below
= 1.65 and 1.42 K for Nd
Rh
Sn
and Nd
Ir
Sn
, respectively, which is similar to that previously reported for Nd
Co
Sn
. These compounds show a magnetic susceptibility saturation behavior below approximately 3 K. The results indicate emergence of anomalous electronic correlation in Nd
Sn
(
= Co, Rh, and Ir) above
.
梶本 亮一; 中村 充孝; 蒲沢 和也*; 稲村 泰弘; 飯田 一樹*; 池内 和彦*; 石角 元志*
EPJ Web of Conferences, 272, p.02007_1 - 02007_8, 2022/11
4SEASONS is a direct geometry time-of-flight spectrometer installed in the Materials and Life Science Experimental Facility, the Japan Proton Accelerator Research Complex. It is used to study atomic andspin dynamics in the energy range of meV to
meV. Since more than a decade has crossed after the first inelastic scattering experiment, it is essential to consider upgrading the instrument to improve its flexibility and performance. In this paper, we discuss the possible medium-term upgrades of key components of the instrument like the chopper system, which are achievable with the current technology and at reasonable cost. Herein, we demonstrated that 4SEASONS can improve the energy resolution by a factor of two, remove frame overlap of adjacent incident energies, significantly improve the asymmetry in the pulse shape, and increase the flux by a factor of
1.5, without major technical difficulties.
梶本 亮一; 中村 充孝; 飯田 一樹*; 蒲沢 和也*; 池内 和彦*; 稲村 泰弘; 石角 元志*
Journal of Neutron Research, 22(2-3), p.99 - 107, 2020/10
The elastic energy resolution, integrated intensity, and peak intensity of the direct-geometry neutron chopper spectrometer 4SEASONS at Japan Proton Accelerator Research Complex (J-PARC) were re-investigated. This was done with respect to the incident energy and the rotation speed of the Fermi chopper using incoherent scattering of vanadium and simple analytical formulas. The model calculations reproduced the observed values satisfactorily. The present work should be useful for estimating in instrument performance in experiments.
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
中性子とミュオンの相補利用により、720Kまでの高温での短距離磁気秩序現象をMnRhSiで発見した。
飯田 一樹*; 吉田 紘行*; 中尾 朗子*; Jeschke, H. O.*; Iqbal, Y.*; 中島 健次; 河村 聖子; 宗像 孝司*; 稲村 泰弘; 村井 直樹; et al.
Physical Review B, 101(22), p.220408_1 - 220408_6, 2020/06
被引用回数:26 パーセンタイル:79.23(Materials Science, Multidisciplinary)鉱物センテニアライトCaCu(OD)
Cl
0.6D
Oの結晶構造と磁気構造をシンクロトロンX線回折と中性子回折測定に密度汎関数理論(DFT)と疑似フェルミオン汎関数繰り込み群(PFFRG)の計算を組み合わせることで調べた。CaCu
(OD)
Cl
0.6D
OではCu
イオンは反強磁性
と幾何学的に完全なカゴメネットワークを形成する。Cu
とCa
イオン間のサイト間無秩序は見つからなかった。CaCu
(OD)
Cl
0.6D
Oは
=7.2K以下で磁気秩序を示し、負のベクトルスピンキラリティーを持つ
=0の磁気構造が現れる。0.3Kでの秩序モーメントは0.58(2)
Bに抑えられている。我々のDFT計算では、この系が量子臨界点の近くにあり、
-
-
カゴメ反強磁性体の優れた実現であることを示唆している。
飯田 一樹*; 古府 麻衣子; 鈴木 雄大*; 村井 直樹; 河村 聖子; 梶本 亮一; 稲村 泰弘; 石角 元志*; 長谷川 舜介*; 益田 隆嗣*; et al.
Journal of the Physical Society of Japan, 89(5), p.053702_1 - 053702_5, 2020/05
被引用回数:21 パーセンタイル:78.71(Physics, Multidisciplinary)We investigated the low-energy incommensurate (IC) magnetic fluctuations in SrRuO
by the high-resolution inelastic neutron scattering measurements and random phase approximation (RPA) calculations. We observed a spin resonance with energy of
meV centered at a characteristic wavevector
. The resonance energy corresponds well to the superconducting gap 2
= 0.56 meV estimated by the tunneling spectroscopy. The spin resonance shows the
modulation with a maximum at around
. The
modulated intensity of the spin resonance and our RPA calculations indicate that the superconducting gaps regarding the quasi-one-dimensional
and
sheets at the Fermi surfaces have the horizontal line nodes. These results may set a strong constraint on the pairing symmetry of Sr
RuO
. We also discuss the implications on possible superconducting order parameters.
中里 晟也*; 岩佐 和晃*; 橋本 大輔*; 塩澤 真未*; 桑原 慶太郎*; 中尾 裕則*; 佐賀山 基*; 石角 元志*; 大原 高志; 中尾 朗子*; et al.
JPS Conference Proceedings (Internet), 30, p.011128_1 - 011128_6, 2020/03
Successive phase transitions of Ir
Sn
(
: La and Ce) were studied using neutron and X-ray diffraction techniques. A semimetal Ce
Ir
Sn
undergoes three phase transitions: an antiferromagnetic ordering characterized by a propagation vector
= (1/2, 1/2, 2/5) below 0.6 K, a structural transformation with
= (1/4, 1/4, 1/4) at 2.0 K, and another structural transformation with
= (1/2, 1/2, 0) above room temperature. La
Ir
Sn
was confirmed to be a superconductor below 2.5 K under the
= (1/2, 1/2, 0) structure that also appears above room temperature.
梶本 亮一; 中島 健次; 藤田 全基*; 石角 元志*; 鳥居 周輝*; 石川 喜久*; Miao, P.*; 神山 崇*
Journal of the Physical Society of Japan, 88(11), p.114602_1 - 114602_6, 2019/11
被引用回数:0 パーセンタイル:0.00(Physics, Multidisciplinary)A high-resolution time-of-flight powder neutron diffraction study of the layered nickel oxide PrSr
NiO
with
and
was performed to characterize the crystal structures of these highly hole-doped nickelates. For the sample with
, the Ni-O bond lengths decrease uniformly with decreasing temperature, and the atomic displacement parameters are similar to those for
. In contrast, for the sample with
, the out-of-plane Ni-O bond length shows a sharp thermal contraction in the high-temperature region, which is suggestive of changes in the orbital occupation accompanied by the development of checkerboard-type charge correlations. Furthermore, the
sample is characterized by a large atomic displacement parameter for the apical O atoms along the out-of-plane direction, which is interpreted as the existence of two types of Ni
sites with different orbital occupancies. The distinct difference between the
sample and the lower-concentration compounds should be related to the development of checkerboard-type charge ordering in the metallic matrix and possible orbital ordering at the Ni
sites at
in the hole-doped layered nickel oxides.
石角 元志*; 樹神 克明; 梶本 亮一; 中村 充孝; 稲村 泰弘; 池内 和彦*; Ji, S.*; 新井 正敏*; 社本 真一
Condensed Matter (Internet), 4(3), p.69_1 - 69_10, 2019/09
中性子非弾性散乱により観測された磁気共鳴モードのQ依存性という初めての手法で、FeTeSe
の超伝導対称性がs
波であることを実験的に示した。
飯田 一樹*; 永井 佑紀; 石田 茂之*; 石角 元志*; 村井 直樹; Christianson, A. D.*; 吉田 紘行*; 稲村 泰弘; 中村 博樹; 中尾 朗子*; et al.
Physical Review B, 100(1), p.014506_1 - 014506_8, 2019/07
被引用回数:39 パーセンタイル:84.23(Materials Science, Multidisciplinary)パルス中性子散乱実験による鉄系超伝導体EuRbFeAs
のスピン揺らぎ、磁気構造の測定を行い、同物質における超伝導体対称性などの議論を行った。
河村 聖子; 高橋 竜太*; 石角 元志*; 山内 康弘*; 中村 雅俊*; 大内 啓一*; 吉良 弘*; 神原 理*; 青山 和弘*; 坂口 佳史*; et al.
Journal of Neutron Research, 21(1-2), p.17 - 22, 2019/05
MLF試料環境チーム低温・マグネットグループは、J-PARC MLFにおいて、利用者の実験のための冷凍機やマグネットの運用を行っている。これまでトップローディング型He冷凍機、ボトムローディング型
He冷凍機、希釈冷凍機インサート、超伝導マグネットを導入してきた。これらの機器の使用頻度は、ビーム出力、課題数の増加に伴い、ここ2年間で急激に高くなってきている。この状況に対応するために運用経験を加味しながら、これらの機器の性能向上作業を進めている。例えば、
He冷凍機の制御ソフトには、自動の初期冷却および再凝縮のプログラムが備わっていたが、新たに、
He potにヒーターを焚くことなくsorbの温度制御のみで
He potを温調するプログラムも作成した。また2017年は、超伝導マグネット用に、揺動型ラジアルコリメーター付きのOVCテールを製作した。このラジアルコリメーターの導入によりデータの質は劇的に向上し、中性子非弾性散乱実験でも超伝導マグネットが使用できるようになった。
梶本 亮一; 石角 元志*; 吉良 弘*; 金子 耕士; 中村 充孝; 蒲沢 和也*; 稲村 泰弘; 池内 和彦*; 飯田 一樹*; 村井 直樹; et al.
Physica B; Condensed Matter, 556, p.26 - 30, 2019/03
被引用回数:3 パーセンタイル:8.82(Physics, Condensed Matter)Magnets are important for studying magnetism and are commonly used as sample environment devices of neutron scattering instruments. However, the use of magnets was prevented at the time-of-flight direct-geometry neutron spectrometer 4SEASONS in Materials and Life Science Experimental Facility (MLF) at J-PARC, because the instrument is surrounded by iron components, and it is equipped with a piece of equipment operated with magnetic bearings. In the present work, we investigate the influence of stray magnetic fields from a superconducting magnet which is shared among neutron scattering instruments in MLF. Based on the investigation, we modified 4SEASONS such that it can be used with the magnet. Finally, we successfully performed the first inelastic neutron scattering experiments with applied magnetic fields using this sample environment.
飯田 一樹*; 吉田 紘行*; 岡部 博孝*; 片山 尚幸*; 石井 裕人*; 幸田 章宏*; 稲村 泰弘; 村井 直樹; 石角 元志*; 門野 良典*; et al.
Scientific Reports (Internet), 9(1), p.1826_1 - 1826_9, 2019/02
被引用回数:13 パーセンタイル:64.91(Multidisciplinary Sciences)Molecular based spin-1/2 triangular lattice systems have attracted research interest. LiMo
O
(
= In or Sc) is such a compound where spin-1/2 Mo
O
clusters in place of Mo ions form the uniform triangular lattice. Here, we report exotic magnetisms in Li
InMo
O
and Li
ScMo
O
investigated by muon spin rotation (
SR) and inelastic neutron scattering (INS) spectroscopies. Li
InMo
O
exhibits spin wave excitation which is quantitatively described by the nearest neighbor anisotropic Heisenberg model based on the 120
spin structure. In contrast, Li
ScMo
O
undergoes short-range magnetic order below 4 K with quantum-spin-liquid-like magnetic fluctuations down to the base temperature. Origin of the different ground states is discussed in terms of anisotropies of crystal structures and magnetic interactions.
中村 充孝; 神原 理*; 飯田 一樹*; 梶本 亮一; 蒲沢 和也*; 池内 和彦*; 石角 元志*; 青山 和弘*
Physica B; Condensed Matter, 551, p.480 - 483, 2018/12
被引用回数:7 パーセンタイル:27.16(Physics, Condensed Matter)近年、磁場や圧力、高温といった特殊環境下での中性子非弾性散乱実験へのニーズが高まっており、質の高いデータを得るためには試料環境機器からの不要な散乱をできる限り低く抑える必要がある。そこで、我々はユーザーのニーズに応えるため、J-PARCのフェルミチョッパー分光器四季に特化した揺動型ラジアルコリメータを開発した。四季では比較的高い入射エネルギーを用いることから、コリメータのブレード素材に水素フリーの金属シートを採用した。このラジアルコリメータの制御システムでは、揺動スピードや揺動角等といった揺動パターンを柔軟に変更することが可能である。本稿では、新たに開発したラジアルコリメータの性能と残された課題について報告する。
石角 元志*; 社本 真一; 樹神 克明; 梶本 亮一; 中村 充孝; Hong, T.*; Mutka, H.*
Scientific Reports (Internet), 8, p.16343_1 - 16343_6, 2018/11
被引用回数:3 パーセンタイル:26.94(Multidisciplinary Sciences)磁気揺らぎはBCS理論に従わない非従来型超伝導で最も可能性のある機構として重要な役割を担うと考えられてきた。今回、これまで磁気ゆらぎが見つかっていない5Kという低い超伝導転移温度の鉄リン系超伝導体LaFePOで、30-50meVの高エネルギーで磁気ゆらぎを見つけた。これはこれまで考えられてきた高エネルギー磁気揺らぎで、高い超伝導転移温度になるという考えとは矛盾することから、超伝導機構の理解に向けて重要な発見である。