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Liu, R.*; 中村 充孝; 蒲沢 和也*; Lu, X.*
Chinese Physics Letters, 41(6), p.067401_1 - 067401_7, 2024/08
被引用回数:0 パーセンタイル:0.00(Physics, Multidisciplinary)Antiferromagnetic spin fluctuation is regarded as the leading driving force for electron pairing in high- superconductors. Here, we use inelastic neutron scattering (INS) to investigate the symmetry and in-plane wave-vector dependence of low-energy spin excitations in uniaxial-strain detwinned FeSe. The low-energy spin excitations ( 10 meV) appear mainly at = ( 1, 0) in the superconducting state ( 9 K) and the nematic state ( 90 K), confirming the constant C rotational symmetry and ruling out the C mode at 3 meV reported in a prior INS study. Moreover, our results reveal an isotropic spin resonance in the superconducting state, which is consistent with the wave pairing symmetry. At slightly higher energy, low-energy spin excitations become highly anisotropic.
Bao, S.*; Gu, Z.-L.*; Shangguan, Y.*; Huang, Z.*; Liao, J.*; Zhao, X.*; Zhang, B.*; Dong, Z.-Y.*; Wang, W.*; 梶本 亮一; et al.
Nature Communications (Internet), 14, p.6093_1 - 6093_9, 2023/09
被引用回数:12 パーセンタイル:92.34(Multidisciplinary Sciences)Magnon polarons are novel elementary excitations possessing hybrid magnonic and phononic signatures, and are responsible for many exotic spintronic and magnonic phenomena. Despite long-term sustained experimental efforts in chasing for magnon polarons, direct spectroscopic evidence of their existence is hardly observed. Here, we report the direct observation of magnon polarons using neutron spectroscopy on a multiferroic FeMoO possessing strong magnon-phonon coupling. Specifically, below the magnetic ordering temperature, a gap opens at the nominal intersection of the original magnon and phonon bands, leading to two separated magnon-polaron bands. Each of the bands undergoes mixing, interconverting and reversing between its magnonic and phononic components. We attribute the formation of magnon polarons to the strong magnon-phonon coupling induced by Dzyaloshinskii-Moriya interaction. Intriguingly, we find that the band-inverted magnon polarons are topologically nontrivial. These results uncover exotic elementary excitations arising from the magnon-phonon coupling, and offer a new route to topological states by considering hybridizations between different types of fundamental excitations.
車地 崇*; 厳 正輝*; 鬼頭 俊介*; 池内 和彦*; 中村 充孝; 池田 暁彦*; 有馬 孝尚*
Journal of Alloys and Compounds, 947, p.169475_1 - 169475_8, 2023/06
被引用回数:3 パーセンタイル:56.29(Chemistry, Physical)We study structural and magnetic properties of rare-earth based semimetals AuGe ( = Y, Gd-Tm, and Lu) using flux-grown single crystals. We evaluate the crystal electric field parameters based on the Stevens operators to reasonably reproduce the temperature dependence of magnetic susceptibilities and specific heat for RAuGe ( = TbTm). The estimated energy scale of the Ising gap ( 11 meV) in TmAuGe is consistent with an excitation observed in an inelastic neutron scattering experiment. These findings suggest an opportunity for interplay between conduction electrons and nontrivial spin structures in the family of magnetic polar semimetals AuGe.
Wu, P.*; 村井 直樹; Li, T.*; 梶本 亮一; 中村 充孝; 古府 麻衣子; 中島 健次; Xia, K.*; Peng, K.*; Zhang, Y.*; et al.
New Journal of Physics (Internet), 25(1), p.013032_1 - 013032_11, 2023/01
被引用回数:0 パーセンタイル:0.00(Physics, Multidisciplinary)The understanding of the lattice dynamics is essential for engineering the thermal transport properties in quantum materials. Based on the canonical point of view, acoustic phonons are believed to be the principal thermal carriers in heat flow. Here, in this work, optical phonons are elucidated to play a pivotal role in determining the lattice thermal conductivity in thermoelectric material SnS by using the state-of-the-art inelastic neutron scattering technique combined with first-principles calculations. Additionally, in contrast to acoustic phonons, optical phonons are observed to exhibit pronounced softening and broadening with temperature. Our observations not only shed light on the significance of the optical phonons in thermal transport but also provide a vital clue to suppress the propagation of optical phonons to optimize the thermoelectric performance of SnS.
飯田 一樹*; 樹神 克明; 稲村 泰弘; 中村 充孝; Chang, L.-J.*; 社本 真一
Scientific Reports (Internet), 12, p.20663_1 - 20663_7, 2022/12
被引用回数:2 パーセンタイル:34.68(Multidisciplinary Sciences)イルメナイトFeTiO粉末サンプルのスピン励起を、飛行時間非弾性中性子散乱によって測定し、動的磁気ペア密度関数を、動的磁気構造因子からフーリエ変換によって初めて得ることに成功した。
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.
服部 高典; 中村 充孝; 飯田 一樹*; 町田 晃彦*; 佐野 亜沙美; 町田 真一*; 有馬 寛*; 大下 英敏*; 本田 孝志*; 池田 一貴*; et al.
Physical Review B, 106(13), p.134309_1 - 134309_9, 2022/10
被引用回数:0 パーセンタイル:0.00(Materials Science, Multidisciplinary)量子調和振動子(QHO)で近似できる蛍石型のZrHとTiHの水素の振動励起を非弾性非干渉性中性子散乱によって21GPaおよび4GPaまで調べた。第一励起の振動エネルギーはそれぞれ(meV) = 141.4(2) + 1.02(2)(GPa)および(meV) = 149.4(1) + 1.21(8)(GPa)で表され、圧力とともに上昇した。格子定数の圧力変化と組み合わせて得られた金属水素原子間距離()との関係は、(meV) = 1.62(9) 10 (および(meV) = 1.47(21) 10 (であった。これらのカーブの傾きは、様々な蛍石型の金属水素化物の常圧下のトレンドに比べ、急峻であった。から得られた水素波動関数の広がりは、格子間サイトよりも縮み易いことが分かった。高圧下における水素の波動関数の優先的な収縮や小さなにおけるの急峻な立ち上がりは金属原子のイオンコアが水素原子よりも堅いために水素原子が高圧下でより狭い領域に閉じ込められるために起こると考えられる。
Yu, Y.*; Yang, C.*; Baggioli, M.*; Phillips, A. E.*; Zaccone, A.*; Zhang, L.*; 梶本 亮一; 中村 充孝; Yu, D.*; Hong, L.*
Nature Communications (Internet), 13, p.3649_1 - 3649_10, 2022/06
被引用回数:17 パーセンタイル:88.26(Multidisciplinary Sciences)The vibrational properties of crystalline bulk materials are well described by Debye theory, which successfully predicts the quadratic low-frequency scaling of the vibrational density of states. However, the analogous framework for nanoconfined materials with fewer degrees of freedom has been far less well explored. Using inelastic neutron scattering, we characterize the vibrational density of states of amorphous ice confined inside graphene oxide membranes and we observe a crossover from the Debye scaling to an anomalous behaviour upon reducing the confinement size L.
勅使河原 誠; 中村 充孝; 金正 倫計; 曽山 和彦
JAEA-Technology 2021-022, 208 Pages, 2022/02
J-PARCの定格出力1MWの物質・生命科学実験施設において、今後の具体的かつ現実的な高度化戦略を展開するため、線源性能に大きく影響する加速器技術(リニアックおよびRCS)、線源技術、中性子・ミュオン輸送技術、検出技術、そしてそれらが結実する中性子・ミュオン ビーム利用装置等の現状(所期設計値に対する到達度)について整理した。さらに、現状分析に基づき出力増強に向けた改良点等について報告する。
吉田 寿雄*; 山本 旭*; 細川 三郎*; 山添 誠司*; 吉川 聡一*; 原 賢二*; 中村 充孝; 蒲沢 和也*; 田中 庸裕*
Topics in Catalysis, 64(9-12), p.660 - 671, 2021/08
被引用回数:2 パーセンタイル:8.71(Chemistry, Applied)Inelastic neutron scattering (INS) enables direct and selective observation of H species due to the extremely large incoherent neutron scattering cross section of a hydrogen atom. In the present study, the adsorbed H species on some heterogeneous precious metal catalysts supported by alumina and carbon black were investigated by in situ INS spectroscopy with a newly designed sample cell. Three alumina-supported metal catalysts having Pt, Pd, and Rh metal nanoparticles with different particle sizes exhibited different INS spectra in intensities and band distribution. Observation of the H species on the metal nanoparticles and the alumina surface revealed their properties. In addition, the H atoms stored in Pd nanoparticles were observed as palladium hydride. In contrast, the H species on a Pt catalyst supported by carbon black were found to be strongly adsorbed on the carbon support.
松川 健*; 飯田 一樹*; 中村 充孝; 石垣 徹*
CrystEngComm (Internet), 23(12), p.2355 - 2359, 2021/03
被引用回数:4 パーセンタイル:48.63(Chemistry, Multidisciplinary)Neutron powder diffraction analysis revealed that ceria transformed into the oxyhydroxide structure by hydrogen treatment. Due to detection of the vibrational modes of both OH and CeH functional groups by inelastic neutron scattering measurements, the CeH functional group was revealed to possibly exist in ceria as an aperiodic structure.
川北 至信; 菊地 龍弥*; 田原 周太*; 中村 充孝; 稲村 泰弘; 丸山 健二*; 山内 康弘*; 河村 聖子; 中島 健次
JPS Conference Proceedings (Internet), 33, p.011071_1 - 011071_6, 2021/03
ヨウ化銅は高温固相で、ヨウ素イオンが作る面心立方格子の隙間を銅イオンが動く超イオン伝導体になることで知られている。溶融相でも、集団的あるいは協調的なイオンの運動を示す特徴がある。MDシミュレーションにおいて、銅イオンの拡散がヨウ素イオンより非常に速いこと分かっている。Cu-Cu部分構造因子にはFSDPと呼ばれる構造を持ち、銅の分布に中距離秩序があることを示している。さらに、Cu-Cu部分二体分布関数は、Cu-Iで形成される最近接分布に深く入り込んでいる。そうした溶融CuIの異常的振る舞いの原因を解明するために、J-PARCの物質・生命科学実験施設に設置されたディスクチョッパー分光器AMATERASを用いて、中性子準弾性散乱(QENS)実験を行った。構造可干渉性のQENSから得られた動的構造因子を理解するため、モード分布解析を行った。その結果、ヨウ素イオンの運動が局所的に閉じ込められた空間で揺らぐような運動であること、一方銅イオンはヨウ素イオンより速く拡散する運動をしていることが分かった。
藤田 全基*; 池内 和彦*; 梶本 亮一; 中村 充孝
Journal of the Physical Society of Japan, 90(2), p.025001_1 - 025001_2, 2021/02
被引用回数:1 パーセンタイル:13.57(Physics, Multidisciplinary)In this short note, we report on the first inelastic neutron scattering (INS) study on high-energy magnetic excitations in SrIrO. We observed excitations between 80 meV and 180 meV. The peak position of the excitations is consistent with the dispersion of a single magnon determined by resonant inelastic X-ray scattering (RIXS) measurement. Thus, our results demonstrate the feasibility of INS for iridates, which has a large neutron absorption cross-section.
山添 誠司*; 山本 旭*; 細川 三郎*; 福田 良一*; 原 賢二*; 中村 充孝; 蒲沢 和也*; 佃 達哉*; 吉田 寿雄*; 田中 庸裕*
Catalysis Science & Technology, 11(1), p.116 - 123, 2021/01
被引用回数:6 パーセンタイル:27.00(Chemistry, Physical)Hydrogen (H) species adsorbed on catalyst surfaces are key intermediates in catalytic hydrogenation reactions over supported metal catalysts. However, individual identification of H species on the metal catalysts has not been established to date. Here, we elucidated the H species on Pt/AlO by the combination of inelastic neutron scattering (INS) and density functional theory (DFT). Several H species in the presence of H were successfully identified at different sites on the Pt surface and AlO support. The INS and FT-IR measurements revealed that the hydride/atop Pt-H, bridged perimeter/terrace Pt-H-Pt, and threefold Pt-H are active intermediates in the CH hydrogenation reaction, whereas the edge Pt-H-Pt is a rather inert species. In addition, the measurements indicate that the AlO itself acts as hydrogen storage material by mediating AlO-H and Al-H-Al species, which serve H species in the CH hydrogenation reaction.
Zhang, D.*; Hu, X.*; Chen, T.*; Abernathy, D. L.*; 梶本 亮一; 中村 充孝; 古府 麻衣子; Foley, B. J.*; Yoon, M.*; Choi, J. J.*; et al.
Physical Review B, 102(22), p.224310_1 - 224310_10, 2020/12
被引用回数:6 パーセンタイル:33.94(Materials Science, Multidisciplinary)The long carrier lifetime and defect tolerance in metal halide perovskites (MHPs) are major contributors to the superb performance of MHP optoelectronic devices. Large polarons were reported to be responsible for the long carrier lifetime. Yet microscopic mechanisms of the large polaron formation, including the so-called phonon melting, are still under debate. Here, time-of-flight inelastic neutron scattering experiments and first-principles density-functional theory calculations were employed to investigate the lattice vibrations (or phonon dynamics) in methylammonium lead iodide, a prototypical example of MHPs. Our findings are that optical phonons lose temporal coherence gradually with increasing temperature which vanishes at the orthorhombic-to-tetragonal structural phase transition. Surprisingly, however, we found that the spatial coherence is still retained throughout the decoherence process. We argue that the temporally decoherent and spatially coherent vibrations contribute to the formation of large polarons in this metal halide perovskite.
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.
Cai, Z.*; Bao, S.*; Wang, W.*; Ma, Z.*; Dong, Z.-Y.*; Shangguan, Y.*; Wang, J.*; Ran, K.*; Li, S.*; 蒲沢 和也*; et al.
Physical Review B, 101(13), p.134408_1 - 134408_10, 2020/04
被引用回数:6 パーセンタイル:33.94(Materials Science, Multidisciplinary)ディラック物質は量子現象と共にキャリアの役割を探索するのに良い系で、磁気ワイル半金属のSrMnSbはワイルフェルミオンとマグノンの関係を研究する良い舞台である。本研究では、SrMnSbの単結晶の中性子非弾性散乱実験を行い、磁性Mn層の分散は約76meVまで広がり、層間の分散は6meVの狭いバンド幅を持つことを見出した。また、これらの実験結果はハイゼンベルグ・スピンハミルトニアンを用いた線形スピン波理論によって再現可能である。本研究では、ワイルフェルミオンとマグノンが共存しているにもかかわらず、SrMnSb中のワイルフェルミオンが磁気ダイナミクスに影響を与えているという明確な証拠は得られなかった。これは、ワイルフェルミオンとマグノンがSb層とMn層に別々に存在し、この擬二次元性による層間結合の弱さに起因するもの考えられる。
上田 宏*; 小野田 繁樹*; 山口 泰弘*; 木村 剛*; 吉澤 大智*; 森岡 俊晶*; 萩原 政幸*; 萩原 雅人*; 左右田 稔*; 益田 隆嗣*; et al.
Physical Review B, 101(14), p.140408_1 - 140408_6, 2020/04
被引用回数:4 パーセンタイル:22.66(Materials Science, Multidisciplinary)We report experimental and theoretical evidence that RbCuMoO has a nonmagnetic tetramer ground state of a two-leg ladder comprising antiferromagnetically coupled frustrated spin- chains and exhibits a Haldane spin gap of emergent spin-1 pairs. Three spin excitations split from the spin-1 triplet by a Dzyaloshinskii-Moriya interaction are identified in inelastic neutron-scattering and electron spin resonance spectra. A tiny magnetic field generates ferroelectricity without closing the spin gap, indicating a unique class of ferroelectricity induced by a vector spin chirality order.
目時 直人; Aczel, A. A.*; 青木 大*; Chi, S.*; Fernandez-Baca, J. A.*; Griveau, J.-C.*; 萩原 雅人*; Hong, T.*; 芳賀 芳範; 池内 和彦*; et al.
JPS Conference Proceedings (Internet), 30, p.011123_1 - 011123_6, 2020/03
希土類(4)やアクチノイド(5)は、電子数の増加とともに複雑さを増し、様々な相互作用が競合して多様な状態が出現する。多体電子系の結晶場分裂はバンド幅より狭いため、(1)高分解能の実験が必要で、(2)遍歴的なCeやU化合物は本質的に明瞭なスペクトルを示さない。また、(3)国際規制物質NpやPuなど超アクチノイド元素の取り扱いは厳しく規制されている。そこで比較的局在性の強い物質や希土類関連物質の、中性子散乱実験による磁気励起の研究が有益である。本稿では重い電子系化合物NpPdAlと関連物質の電子状態について述べる。
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。