JOPSS:検索結果一覧

検索結果：　41 件中 1件目～20件目を表示

発表形式

Initialising ...

選択項目を絞り込む

掲載資料名

Initialising ...

発表会議名

Initialising ...

筆頭著者名

Initialising ...

キーワード

Initialising ...

使用言語

Initialising ...

発行年

Initialising ...

開催年

Initialising ...

論文

Spin gap in the weakly interacting quantum spin chain antiferromagnet KCuPO $_{4}$ H $_{2}$ O

藤原理賀; 萩原雅人; 森田克洋*; 村井直樹; 幸田章宏*; 岡部博孝*; 満田節生*

Physical Review B, 107(5), p.054435_1 - 054435_8, 2023/02

https://doi.org/10.1103/PhysRevB.107.054435

被引用回数：0 パーセンタイル：0.01(Materials Science, Multidisciplinary)

= 1/2ハイゼンベルグ直線鎖反強磁性体は、最も単純なスピンモデルであるが、様々な量子多体現象のプラットフォームを提供する。この論文では、準一次元反強磁性体KCuPO $_{4}$ H $_{2}$ Oの磁性を報告した。 $T_{rm{N}}$ = 11.7(1) Kにおいて、格子整合な長距離反強磁性秩序が形成され、その磁気モーメントの大きさは0.31(1) $mu_{rm{B}}$ である事がわかった。また鎖内相互作用と鎖間相互作用の大きさはそれぞれ172Kと4.25(4) Kと見積もられ、/の比は0.0247(3)である。中性子非弾性散乱実験により、 $T_{rm{N}}$ より高温では、一次元ハイゼンベルグ量子スピン鎖の特徴である連続体励起スペクトルが観測され、 $T_{rm{N}}$ より低温では、分散励起にスピンギャップが観測された。これらの結果は、弱く結合した = 1/2ハイゼンベルグスピン鎖系で観測される性質と一致する。

論文

Experimental evidence for the significance of optical phonons in thermal transport of tin monosulfide

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

https://doi.org/10.1088/1367-2630/acb3ed

被引用回数：0 パーセンタイル：0.02(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.

論文

Partial breakdown of translation symmetry at a structural quantum critical point associated with a ferroelectric soft mode

石井悠衣*; 山本有梨沙*; 佐藤直大*; 南部雄亮*; 河村聖子; 村井直樹; 尾原幸治*; 河口彰吾*; 森孝雄*; 森茂生*

Physical Review B, 106(13), p.134111_1 - 134111_7, 2022/10

https://doi.org/10.1103/PhysRevB.106.134111

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

We report that complete suppression of a phonon-driven structural phase transition causes partial breakdown of a three-dimensional translation symmetry in a well-defined sublattice. This state is revealed for a dielectric compound, Ba $_{1-x}$ SrAlO, that comprises an AlO network incorporated into a hexagonal Ba(Sr) sublattice. Pair distribution function analyses and inelastic neutron scattering experiments provide clear-cut evidence of the AlO network forming a continuum of Al-O short-range correlations similar to glasses, whereas the Ba(Sr) sublattice preserves the original translational symmetry. This glassy network significantly dampens the phonon spectrum and transforms it into the broad one resembling those typically observed in glass materials.

論文

Anisotropic magnon damping by zero-temperature quantum fluctuations in ferromagnetic CrGeTe $_{3}$

Chen, L.*; Mao, C.*; Chung, J.-H.*; Stone, M. B.*; Kolesnikov, A. I.*; Wang, X.*; 村井直樹; Gao, B.*; Delaire, O.*; Dai, P.*

Nature Communications (Internet), 13, p.4037_1 - 4037_7, 2022/07

https://doi.org/10.1038/s41467-022-31612-w

被引用回数：1 パーセンタイル：41.54(Multidisciplinary Sciences)

Spin and lattice are two fundamental degrees of freedom in a solid, and their fluctuations about the equilibrium values in a magnetic ordered crystalline lattice form quasiparticles termed magnons (spin waves) and phonons (lattice waves), respectively. In most materials with strong spin-lattice coupling (SLC), the interaction of spin and lattice induces energy gaps in the spin wave dispersion at the nominal intersections of magnon and phonon modes. Here we use neutron scattering to show that in the two-dimensional (2D) van der Waals honeycomb lattice ferromagnetic CrGeTe $_{3}$ , spin waves propagating within the 2D plane exhibit an anomalous dispersion, damping, and breakdown of quasiparticle conservation, while magnons along the c axis behave as expected for a local moment ferromagnet. These results indicate the presence of dynamical SLC arising from the zero-temperature quantum fluctuations in CrGeTe $_{3}$ , suggesting that the observed in-plane spin waves are mixed spin and lattice quasiparticles fundamentally different from pure magnons and phonons.

論文

Recent update of AMATERAS; A Cold-neutron disk-chopper spectrometer

中島健次; 河村聖子; 古府麻衣子; 村井直樹; 稲村泰弘; 菊地龍弥*; 若井大介*

JPS Conference Proceedings (Internet), 33, p.011089_1 - 011089_7, 2021/03

https://doi.org/10.7566/JPSCP.33.011089

J-PARCに設置されている冷中性子ディスクチョッパー型分光器AMATERASの近況について報告する。最後に報告を行った2017年以降、新たな検出器の増設、散乱真空槽の真空系の更新作業(継続中)等を行っている。また、分解能について再調査を実施した。この他、2018年、2019年のJ-PARCの1MW試験時に試験測定も行った。今後の高度化計画についても触れる。

論文

Field-tuned magnetic structure and phase diagram of the honeycomb magnet YbCl

Hao, Y. Q.*; Wo, H. L.*; Gu, Y. M.*; Zhang, X. W.*; Gu, Y. Q.*; Zheng, S. Y.*; Zhao, Y.*; Xu, G. Y.*; Lynn, J. W.*; 中島健次; et al.

Science China; Physics, Mechanics & Astronomy, 64(3), p.237411_1 - 237411_6, 2021/03

https://doi.org/10.1007/s11433-020-1626-3

被引用回数：3 パーセンタイル：52.75(Physics, Multidisciplinary)

We report thermodynamic and neutron diffraction measurements on the magnetic ordering properties of the honeycomb lattice magnet YbCl. We find YbCl exhibits a Nel type long-range magnetic order at the wavevector (0, 0, 0) below T = 600 mK. This magnetic order is associated with a small sharp peak in heat capacity and most magnetic entropy release occurs above the magnetic ordering temperature. The magnetic moment lies in-plane, parallel to the monoclinic a-axis, whose magnitude m $_{rm Yb}$ = 0.86(3) is considerably smaller than the expected fully ordered moment of 2.24 for the doublet crystal-field ground state. The magnetic ordering moment gradually increases with increasing magnetic field perpendicular to the ab-plane, reaching a maximum value of 1.6(2) at 4 T, before it is completely suppressed above 9 T. These results indicate the presence of strong quantum fluctuations in YbCl.

論文

=0 long-range magnetic order in centennialite CaCu $_{3}$ (OD) $_{6}$ Cl $_{2}$ 0.6D $_{2}$ O; A Spin- $frac{1}{2}$ perfect kagome antiferromagnet with $J_{1}$ - $J_{2}$ - $J_{d}$

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

https://doi.org/10.1103/PhysRevB.101.220408

被引用回数：18 パーセンタイル：82.95(Materials Science, Multidisciplinary)

鉱物センテニアライトCaCu $_{3}$ (OD) $_{6}$ Cl $_{2}$ 0.6D $_{2}$ 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 $_{3}$ (OD) $_{6}$ Cl $_{2}$ 0.6D $_{2}$ OではCu $^{2+}$ イオンは反強磁性 $J_{1}$ と幾何学的に完全なカゴメネットワークを形成する。Cu $^{2+}$ とCa $^{2+}$ イオン間のサイト間無秩序は見つからなかった。CaCu $_{3}$ (OD) $_{6}$ Cl $_{2}$ 0.6D $_{2}$ Oは $_{rm N}$ =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、 $J_{1}$ - $J_{2}$ - $J_{d}$ 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。

論文

Horizontal line nodes in SrRuO proved by spin resonance

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

https://doi.org/10.7566/JPSJ.89.053702

被引用回数：15 パーセンタイル：81.4(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 $hbar omega_{rm res}0.56$ meV centered at a characteristic wavevector $Q_{rm res}=(0.3,0.3,0.5)$ . 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 SrRuO. We also discuss the implications on possible superconducting order parameters.

論文

Lattice dynamics in FeSe via inelastic X-ray scattering and first-principles calculations

村井直樹; 福田竜生; 中島正道*; 河村光晶*; 石川大介*; 田島節子*; Baron, A. Q. R.*

Physical Review B, 101(3), p.035126_1 - 035126_6, 2020/01

https://doi.org/10.1103/PhysRevB.101.035126

被引用回数：5 パーセンタイル：41.49(Materials Science, Multidisciplinary)

非弾性X線散乱を用いたFeSe超伝導体のフォノン研究について報告する。実験的に決定したフォノン分散と非磁性相の密度汎関数理論(DFT)とを比較を行うと、両所の間には顕著な不一致が見られた。FeSeは磁気秩序を示さないにもかかわらず、スピン偏極DFTを用いることによって初めて実験結果は再現される。この解析は、強いスピン揺らぎを内在した常時性状態における近似を与える。

論文

Experimental investigation of the suppressed superconducting gap and double-resonance mode in Ba $_{1-x}$ K $_{x}$ Fe $_{2}$ As $_{2}$

出田真一郎*; 村井直樹; 中島正道*; 梶本亮一; 田中清尚*

Physical Review B, 100(23), p.235135_1 - 235135_7, 2019/12

https://doi.org/10.1103/PhysRevB.100.235135

被引用回数：2 パーセンタイル：5.76(Materials Science, Multidisciplinary)

Ba $_{1-x}$ K $_{x}$ Fe $_{2}$ As $_{2}$ has an exotic physical property where that the C $_{2}$ -SDW phase suddenly changes to the C $_{4}$ -magnetic phase and superconductivity is suppressed within a narrow composition range around x = 0.25. We have investigated the doping dependence of the electronic structure of Ba $_{1-x}$ K $_{x}$ Fe $_{2}$ As $_{2}$ using angle-resolved photoemission spectroscopy (ARPES) and found an anomaly in the superconducting (SC) gap structure only for x = 0.25 in both the hole and electron Fermi surfaces (FSs). We also propose that the mechanism of a newly observed double-resonance peak by inelastic neutron scattering is understandable by the SC gap obtained by ARPES. Our discovery reveals the important relationship between the C $_{4}$ - magnetic phase and superconductivity, and provides an opportunity to survey the underlying relationship between the SC gap and resonance mode in the hole-doped iron-based superconductor.

論文

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

BB2018-0570.pdf:2.17MB

https://doi.org/10.1016/j.physb.2018.11.065

被引用回数：2 パーセンタイル：12.72(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.

論文

Quantum magnetisms in uniform triangular lattices Li $_{2}$ Mo $_{3}$ O $_{8}$ ( = 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

https://doi.org/10.1038/s41598-018-36123-7

被引用回数：6 パーセンタイル：52.78(Multidisciplinary Sciences)

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

論文

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

BB2016-1727.pdf:0.39MB

https://doi.org/10.1088/1742-6596/1021/1/012030

被引用回数：3 パーセンタイル：90.64

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.

論文

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

https://doi.org/10.1103/PhysRevB.97.241112

被引用回数：5 パーセンタイル：28.94(Materials Science, Multidisciplinary)

非弾性中性子散乱による鉄系超伝導体Ba $_{0.75}$ K $_{0.25}$ Fe $_{2}$ As $_{2}$ の磁気励起測定を行い、約200meV程度のバンド幅を持つスピン波的分散を観測した。測定されたスペクトルは、同一試料に対する角度分解光電子分光測定により得られた電子バンドの繰り込み因子を考慮し、密度汎関数理論により構築された5軌道ハバード模型に乱雑位相近似を適応する事で再現される。これらの結果は電子バンドの繰り込みという形でしばしば現れる所謂、電子相関効果の観測が非弾性中性子散乱によっても可能であることを示すものである。

論文

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

https://doi.org/10.1038/s41598-018-27984-z

被引用回数：5 パーセンタイル：28.94(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.

論文

Spin resonance in the new-structure-type iron-based superconductor CaKFe $_{4}$ As $_{4}$

飯田一樹*; 石角元志*; 永井佑紀; 吉田紘行*; Christianson, A. D.*; 村井直樹; 川島健司*; 吉田良行*; 永崎洋*; 伊豫彰*

Journal of the Physical Society of Japan, 86(9), p.093703_1 - 093703_4, 2017/09

https://doi.org/10.7566/JPSJ.86.093703

被引用回数：23 パーセンタイル：81.13(Physics, Multidisciplinary)

The dynamical spin susceptibility in the new-structure iron-based superconductor CaKFe $_{4}$ As $_{4}$ was investigated by a combination of inelastic neutron scattering (INS) measurements and random phase approximation (RPA) calculations. Powder INS measurements show that the spin resonance at Q $_{rm res}$ = 1.17(1) vector in the tetragonal notation, evolves below Tc. The characteristic energy of the spin resonance E $_{rm res}$ = 12.5 meV is smaller than twice the size of the superconducting gap (2). The broad energy feature of the dynamical susceptibility of the spin resonance can be explained by the RPA calculations which take into account the different superconducting gaps on the different Fermi surfaces. Our INS and PRA studies demonstrated that the superconducting pairing nature in CaKFe $_{4}$ As $_{4}$ is the s symmetry.

論文

Effect of magnetism on lattice dynamics in SrFeAs using high-resolution inelastic X-ray scattering

村井直樹*; 福田竜生; 小林達也*; 中島正道*; 内山裕士*; 石川大介*; 筒井智嗣*; 中村博樹; 町田昌彦; 宮坂茂樹*; et al.

Physical Review B, 93(2), p.020301_1 - 020301_5, 2016/01

https://doi.org/10.1103/PhysRevB.93.020301

被引用回数：7 パーセンタイル：36.13(Materials Science, Multidisciplinary)

Phonon spectra of detwinned SrFeAs crystals, as measured by inelastic X-ray scattering, show clear anisotropyaccompanying the magnetostructural transition at 200 K. We model the mode splitting using magnetic DFT calculations, including a phenomenological reduction in force-constant anisotropy that can be attributed to magnetic fluctuations. This serves as a starting point for a general model of phonons in this material applicable to both the antiferromagnetically ordered phase and the paramagnetic phase. Using this model, the measured splitting in the magnetic phase below T, and the measured phonon linewidth, we set a lower bound on the mean magnetic fluctuation frequency above T at 210 K.

口頭

非弾性X線散乱による鉄系超伝導体SrFeAsのフォノン分散における磁気秩序の影響

村井直樹*; 福田竜生; 内山裕士*; 筒井智嗣*; 石川大介*; 小林達也*; 中村博樹; 町田昌彦; 中島正道*; 宮坂茂樹*; et al.

no journal, ,

鉄系超伝導体の母物質であるSrFeAsは約200Kで磁気相転移を伴った正方晶から斜方晶への構造相転移を示す。我々は、一軸圧の印加により非双晶化されたSrFeAsに対して非弾性X線散乱実験を行い、磁気・構造転移に伴う特異なフォノン異方性の有無を調べた。本講演では観測された強いフォノン異方性の詳細について議論する。

口頭

Magneto-elastic coupling in detwinned Sr(Fe $_{1-x}$ Co)As by inelastic X-ray scattering

村井直樹*; 福田竜生; 中島正道*; 小林達也*; 内山裕士*; 筒井智嗣*; 石川大介*; 中村博樹; 町田昌彦; 宮坂茂樹*; et al.

no journal, ,

We present phonon dispersion measurements from detwinned single crystals of Sr(Fe $_{1-x}$ Co)As with different doping levels(=0 and 0.08) using inelastic X-ray scattering with 1.5 meV resolution at SPring-8. The crystals were detwinned by application of in-plane uniaxial stress. This allowed us to measure single domain phonon structure in the magnetically ordered state. We clearly identified the change in the phonon dispersion induced by the onset of magnetic order, with phonon energies depending on orientation of the phonon wave vector relative to the Fe moment. We compare our results to pseudo potential calculations: Magnetic calculations give better agreement than non-magnetic calculations, but in most parts of the Brillouin zone investigated, they overestimate the magnitude of the mode splitting and in fact often fail to predict even the correct sign of the splitting.

口頭

Effect of magnetism on lattice dynamics of SrFe $_{2}$ As $_{2}$ via high-resolution inelastic X-ray scattering

村井直樹; 福田竜生; 小林達也*; 中島正道*; 内山裕士*; 石川大介*; 筒井智嗣*; 中村博樹; 町田昌彦; 宮坂茂樹*; et al.

no journal, ,

高分解能非弾性X線を用いた鉄系超伝導体SrFe $_{2}$ As $_{2}$ のフォノン分散の測定結果を報告する。結晶の非双晶化により、二方向の等価な移行運動量方向におけるフォノン分散の異方性の観測に初めて成功した。しかしこの観測結果は、密度汎関数法が予想する異方性よりもかなり小さいものである。実験と計算結果との比較から、磁気揺らぎのフォノンへの寄与を想定し、その効果を現象論的に取り込んだモデルを提唱した。そのモデルから得られた計算により磁気転移点上下のフォノンの振る舞いを非常に良く再現することに成功した。