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Study on use of superconducting magnet and first inelastic neutron scattering experiment under magnetic field at 4SEASONS spectrometer

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:1 パーセンタイル:100(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.



中島 健次; Harjo, S.; 山田 悟史*; 及川 健一; 梶本 亮一

JAEA-Review 2018-032, 43 Pages, 2019/02




Quantum magnetisms in uniform triangular lattices Li$$_{2}$$$$A$$Mo$$_{3}$$O$$_{8}$$ ($$A$$ = In, Sc)

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

 パーセンタイル:100(Multidisciplinary Sciences)

Molecular based spin-1/2 triangular lattice systems have attracted research interest. Li$$_2$$$$A$$Mo$$_3$$O$$_8$$ ($$A$$ = In or Sc) is such a compound where spin-1/2 Mo$$_3$$O$$_{13}$$ clusters in place of Mo ions form the uniform triangular lattice. Here, we report exotic magnetisms in Li$$_2$$InMo$$_3$$O$$_8$$ and Li$$_2$$ScMo$$_3$$O$$_8$$ investigated by muon spin rotation ($$mu$$SR) and inelastic neutron scattering (INS) spectroscopies. Li$$_2$$InMo$$_3$$O$$_8$$ exhibits spin wave excitation which is quantitatively described by the nearest neighbor anisotropic Heisenberg model based on the 120$$^{circ}$$ spin structure. In contrast, Li$$_2$$ScMo$$_3$$O$$_8$$ 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.


Proceedings of the User Group Meeting on MLF Spectrometers (DIRECTION 2018); October 11, 2018, Ibaraki Quantum Beam Research Center (Tokai, Ibaraki, Japan)

梶本 亮一; 横尾 哲也*; 松浦 直人*

JAEA-Review 2018-024, 78 Pages, 2019/01


平成30年10月11日、MLF中性子分光器による合同のユーザーミーティング「DIRECTION 2018」が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。本ミーティングは6つの分光器、すなわちBL01(4SEASONS)、BL02(DNA)、BL06(VIN ROSE)、BL12(HRC)、BL14(AMATERAS)、BL23(POLANO)におけるユーザー利用の活性化およびユーザーと装置の協力関係の構築を目指して開催されたものである。研究会では14件の口頭発表および21件のポスター発表が行われ、各装置を利用して行われた研究成果の紹介、各装置や試料環境に関する現状の報告がなされるとともに、装置や試料環境に関する要望や今後の展開等について密接な議論が交わされた。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。


High-energy magnetic excitations in lightly oxygen-doped lanthanum nickel oxides

中島 健次; 梶本 亮一

Physica B; Condensed Matter, 551, p.142 - 145, 2018/12

 パーセンタイル:100(Physics, Condensed Matter)

We will report on magnetic excitations in lightly oxygen doped lanthanum nickel oxide, La$$_{2}$$NiO$$_{4+delta}$$. By introducing slightly excessive oxygen atoms in the system, magnetic excitations in La$$_{2}$$NiO$$_{4}$$ drastically changes its picture. In lower energy region, spin-wave stiffness strongly suppressed. On the other hand, in the higher energy region, spin-wave dispersion curve is almost same as in the stoichiometric system, while excitations show considerable broadening. Alternation of the character of the excitations by changing energy is also reported in hole doped cuprates and cobalates. We consider that this behavior is one of key clues to understand magnetism and transport properties in carrier doped layered transition metal oxides. We investigated detail of magnetic excitations in two different lightly doped systems, La$$_{2}$$NiO$$_{4.02}$$ and La$$_{2}$$NiO$$_{4.11}$$ in wide momentum and energy transfer space by using time-of-flight spectrometers at J-PARC. Observed doping effects in magnetic excitations will be discussed by comparing them to those reported in other related layered transition metal oxides.


Performances of oscillating radial collimator for the Fermi chopper spectrometer 4SEASONS at J-PARC

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

 パーセンタイル:100(Physics, Condensed Matter)



High-energy spin fluctuation in low-T$$_{c}$$ iron-based superconductor LaFePO$$_{0.9}$$

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

 パーセンタイル:100(Multidisciplinary Sciences)



Al-impurity-induced magnetic excitations in heavily over-doped La$$_{1.7}$$Sr$$_{0.3}$$Cu$$_{0.95}$$Al$$_{0.05}$$O$$_{4}$$

池内 和彦*; 中島 健次; 河村 聖子; 梶本 亮一; 脇本 秀一; 鈴木 謙介*; 藤田 全基*

AIP Advances (Internet), 8(10), p.101318_1 - 101318_5, 2018/10



Schottky specific heat of the lightly Mn-substituted electron-doped SrTiO$$_3$$

奥田 哲治*; 梶本 亮一; 野田 正亮*; 桑原 英樹*

AIP Advances (Internet), 8(10), p.101339_1 - 101339_5, 2018/10

Large changes in the low-temperature specific heat (low-$$TC$$) by applying magnetic fields up to 9 Tesla were found in the lightly Mn-substituted electron-doped perovskites Sr$$_{1-x}$$La$$_{x}$$TiO$$_{3}$$. The changes in the low-$$TC$$ are qualitatively well explained by the Schottky specific heat ($$C_mathrm{Sch}$$) of localized spins of the Mn 3d electrons in weak internal magnetic fields via itinerant electrons. According to the analysis by using the conventional model, the doped Mn ions are apparently not Mn$$^{4+}$$ ($$S$$ = 3/2) ions, but are Jahn-Teller active Mn$$^{3+}$$ ($$S$$ = 2) ions or mixtures of Mn$$^{3+}$$ and Mn$$^{2+}$$ ions. However, the actual numbers of localized spins estimated from $$C_mathrm{Sch}$$ are about 30% smaller than the expected values. Part of the localized spins of the Mn 3d electrons may disappear due to Kondo coupling with the itinerant electrons, leading to the observed enhancement of the electronic specific heat coefficients.


Neutron inelastic scattering study of the $$f$$-electron states in NdPd$$_5$$Al$$_2$$

目時 直人; 山内 宏樹; 鈴木 博之*; 北澤 英明*; 蒲沢 和也*; 池内 和彦*; 梶本 亮一; 中村 充孝; 稲村 泰弘

Journal of the Physical Society of Japan, 87(8), p.084708_1 - 084708_7, 2018/08

 被引用回数:3 パーセンタイル:15.52(Physics, Multidisciplinary)

$$f$$電子化合物NdPd$$_5$$Al$$_2$$の中性子散乱による研究を行った。0K, 35.4K, 88.3K, 101.5K, and 198.8Kの結晶場レベルを励起スペクトルから明らかにした。$$Gamma_6$$基底状態は主として$$J_z=pm9/2$$の軌道によって構成され、これが大きな負の$$B_{20}=-1.4$$Kと一軸異方性を生じる。結晶場から計算された磁気モーメント, 帯磁率, 磁化曲線, 比熱は実験をよく説明する。CePd$$_5$$Al$$_2$$やPrPd$$_5$$Al$$_2$$と共通した電荷分布の存在は同じ構造を持つアクチノイド化合物においても局在的な性質が重要で、UPd$$_5$$Al$$_2$$の局在5$$f$$電子状態やNpPd$$_5$$Al$$_2$$の重い電子系超伝導にその価数の不安定性が重要な役割をすることを示している。


Status report of the chopper spectrometer 4SEASONS

梶本 亮一; 中村 充孝; 稲村 泰弘; 蒲沢 和也*; 池内 和彦*; 飯田 一樹*; 石角 元志*; 村井 直樹; 吉良 弘*; 中谷 健; et al.

Journal of Physics; Conference Series, 1021(1), p.012030_1 - 012030_6, 2018/06

4SEASONS is a medium-resolution thermal neutron chopper spectrometer in the Materials and Life Science Experimental Facility (MLF) at J-PARC. Although 4SEASONS is routinely used for many experiments by internal and external users, upgrading and maintenance work is still underway. This paper reviews the recent improvements of the instrument.


Effect of electron correlations on spin excitation bandwidth in Ba$$_{0.75}$$K$$_{0.25}$$Fe$$_{2}$$As$$_{2}$$ as seen via time-of-flight inelastic neutron scattering

村井 直樹; 鈴木 雄大*; 出田 真一郎*; 中島 正道*; 田中 清尚*; 池田 浩章*; 梶本 亮一

Physical Review B, 97(24), p.241112_1 - 241112_6, 2018/06

 被引用回数:3 パーセンタイル:51.17(Materials Science, Multidisciplinary)



Odd and even modes of neutron spin resonance in the bilayer iron-based superconductor CaKFe$$_{4}$$As$$_{4}$$

Xie, T.*; Wei, Y.*; Gong, D.*; Fennell, T.*; Stuhr, U.*; 梶本 亮一; 池内 和彦*; Li, S.*; Hu, J.*; Luo, H.*

Physical Review Letters, 120(26), p.267003_1 - 267003_7, 2018/06

 被引用回数:3 パーセンタイル:15.52(Physics, Multidisciplinary)

We report an inelastic neutron scattering study on the spin resonance in the bilayer iron-based superconductor CaKFe$$_4$$As$$_4$$. In contrast to its quasi-two-dimensional electron structure, three strongly $$L$$-dependent modes of spin resonance are found below $$T_c$$ = 35 K. The mode energies are below and linearly scale with the total superconducting gaps summed on the nesting hole and electron pockets, essentially in agreement with the results in cuprate and heavy fermion superconductors. This observation supports the sign-reversed Cooper-pairing mechanism under multiple pairing channels and resolves the long-standing puzzles concerning the broadening and dispersive spin resonance peak in iron pnictides. More importantly, the triple resonant modes can be classified into odd and even symmetries with respect to the distance of Fe-Fe planes within the Fe-As bilayer unit. Thus, our results closely resemble those in the bilayer cuprates with nondegenerate spin excitations, suggesting that these two high-$$T_c$$ superconducting families share a common nature.


Elastic and dynamical structural properties of La and Mn-doped SrTiO$$_{3}$$ studied by neutron scattering and their relation with thermal conductivities

梶本 亮一; 中村 充孝; 村井 直樹; 社本 真一; 本田 孝志*; 池田 一貴*; 大友 季哉*; 畑 博人*; 江藤 貴弘*; 野田 正亮*; et al.

Scientific Reports (Internet), 8(1), p.9651_1 - 9651_8, 2018/06

 被引用回数:2 パーセンタイル:55.67(Multidisciplinary Sciences)

The electron-doped SrTiO$$_{3}$$ exhibits good thermoelectric properties, which makes this material a promising candidate of an n-type oxide thermoelectric device. Recent studies indicated that only a few percent co-doping of La and Mn in SrTiO$$_{3}$$ substantially reduces the thermal conductivity, thereby greatly improving the thermoelectric figure of merit at room temperature. Our time-of-flight neutron scattering studies revealed that by doping both La and Mn into SrTiO$$_{3}$$, the inelastic scattering spectrum shows a momentum-independent increase in the low-energy spectral weight approximately below 10 meV. The increase in the low-energy spectral weight exhibits a clear correlation with thermal conductivity. The correlation is attributed to dynamical and local structural fluctuations caused by the Jahn-Teller instability in Mn$$^{3+}$$ ions coupled with the incipient ferroelectric nature of SrTiO$$_{3}$$, as the origin of the low thermal conductivity.


Instrumental resolution of the chopper spectrometer 4SEASONS evaluated by Monte Carlo simulation

梶本 亮一; 佐藤 研太朗*; 稲村 泰弘; 藤田 全基*

AIP Conference Proceedings 1969, p.050004_1 - 050004_8, 2018/05

We performed simulations of the resolution function of the 4SEASONS spectrometer at J-PARC by using the Monte Carlo simulation package McStas. The simulations showed reasonably good agreement with analytical calculations of energy and momentum resolutions by using a simplified description. We implemented new functionalities in Utsusemi, the standard data analysis tool used in 4SEASONS, to enable visualization of the simulated resolution function and predict its shape for specific experimental configurations.


Magnetic excitations in the orbital disordered phase of MnV$$_2$$O$$_4$$

松浦 慧介*; 佐賀山 基*; 上原 周*; 新居 陽一*; 梶本 亮一; 蒲沢 和也*; 池内 和彦*; Ji, S.*; 阿部 伸行*; 有馬 孝尚*

Physica B; Condensed Matter, 536, p.372 - 376, 2018/05

 パーセンタイル:100(Physics, Condensed Matter)

We have investigated the temperature dependence of magnetic dynamics in a spinel-type vanadium oxide MnV$$_2$$O$$_4$$ by inelastic neutron scattering. The scattering intensity of excitation around 20 meV disappears in the collinear intermediate-temperature cubic-ferrimagnetic phase, which reveals that this excitation should be peculiar to the orbital ordered phase. We have found a weakly dispersive mode emergent from a non-integer wavevector $$(1.4,1.4,0)$$ at 56 K, which lies in the cubic-ferrimagnetic phase between non-coplanar ferrimagnetic and paramagnetic phases. This indicates that the probable presence of an incommensurate instability in the simple collinear structure.


Detailed study of the structure of the low-energy magnetic excitations in overdoped La$$_{1.75}$$Sr$$_{0.25}$$CuO$$_{4}$$

池内 和彦*; 菊地 龍弥*; 中島 健次; 梶本 亮一; 脇本 秀一; 藤田 全基*

Physica B; Condensed Matter, 536, p.717 - 719, 2018/05

 被引用回数:1 パーセンタイル:55.67(Physics, Condensed Matter)

銅酸化物高温超伝導体の過剰ドープ領域における低エネルギーの磁気励起の構造の詳細を調べるために、我々は、La$$_{1.75}$$Sr$$_{0.25}$$CuO$$_{4}$$の中性子非弾性散乱実験を行った。過去に報告されたように、非整合な磁気相関に対応した$$Q_{rm tet}$$ = (0.5 $$pm$$ $$delta$$, 0.5)/(0.5, 0.5 $$pm$$ $$delta$$)を中心とした磁気励起を明瞭に観測した。それに加えて、$$Q_{rm tet}=(0.5, 0.5)$$を中心とした円環状の励起も観測された。円環の半径($$r$$=0.109)は、磁気相関の非整合性($$delta$$=0.118)より小さい。このことは、円環状の磁気励起は非整合な磁気相関とはその原因を異にしていることを示唆している。La$$_{2-x}$$Sr$$_{x}$$CuO$$_{4}$$の磁気励起はこのように2種類の励起を持つことが示唆される。


Fe-impurity-induced magnetic excitations in heavily over-doped La$$_{1.7}$$Sr$$_{0.3}$$Cu$$_{0.95}$$Fe$$_{0.05}$$O$$_{4}$$

池内 和彦*; 菊地 龍弥*; 中島 健次; 梶本 亮一; 脇本 秀一; 藤田 全基*

Journal of Physics; Conference Series, 969(1), p.012024_1 - 012024_5, 2018/04

Inelastic neutron scattering experiments were performed to investigate the effect of Fe substitution on the magnetic excitation spectra in a heavily hole-doped cuprate system La$$_{1.7}$$Sr$$_{0.3}$$Cu$$_{0.95}$$Fe$$_{0.05}$$O$$_{4}$$. Well-defined low-energy magnetic excitations, associated with a static magnetic order, were observed at the incommensurate (IC) positions. The incommensurability of 0.144 (r.l.u) was larger than that of $$sim$$0.125 (r.l.u) in LSCO with $$x$$ = 0.25, suggesting an increase of incommensurability by Fe substitution. In addition to the obvious effect on IC excitations, we show the emergence of ring-shaped magnetic excitations by Fe-substitution. These results are incompatible with a simple pinning scenario of the stripe order, which is characterized by local spin correlations. The metallic aspect of the low-energy part of the magnetic excitation, which underlies high-temperature superconductivity in over-doped cuprate systems, would be enhanced/induced by Fe substitution.


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。


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


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