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論文

Science from the initial operation of HRC

伊藤 晋一*; 横尾 哲也*; 益田 隆嗣*; 吉澤 英樹*; 左右田 稔*; 池田 陽一*; 井深 壮史*; 川名 大地*; 佐藤 卓*; 南部 雄亮*; et al.

JPS Conference Proceedings (Internet), 8, p.034001_1 - 034001_6, 2015/09

Since the installation of the High Resolution Chopper Spectrometer, HRC, experiments using the HRC are being conducted to observe the dynamics in wide range of physics. Scientific results during the period since the initial construction are summarized.

論文

Electronic excitations around the substituted atom in La$$_2$$Cu$$_{1-y}$$N$$_y$$O$$_4$$ as seen via resonant inelastic X-ray scattering

石井 賢司; 筒井 健二; 池内 和彦*; Jarrige, I.; 水木 純一郎; 平賀 晴弘*; 山田 和芳*; 遠山 貴己*; 前川 禎通; 遠藤 康夫*; et al.

Physical Review B, 85(10), p.104509_1 - 104509_5, 2012/03

 被引用回数:3 パーセンタイル:79.94(Materials Science, Multidisciplinary)

We perform a resonant inelastic X-ray scattering (RIXS) study of Ni-substituted La$$_2$$CuO$$_4$$ and Cu-substituted La$$_2$$NiO$$_4$$.Resonantly enhanced charge-transfer excitations are successfully observed by tuning the incident photon energy to the $$K$$-edge of the substituted element. These excitations display a very weak momentum dependence, evidencing their local character. We find a shift in the energy of the onset edge of these features compared with the non-substituted compounds La$$_2$$CuO$$_4$$ and La$$_2$$NiO$$_4$$. This shift is quantitatively reproduced by exact diagonalization calculations of the RIXS spectra. RIXS is shown to be a powerful tool to probe the electronic states of substituted elements and to understand their interaction with surrounding atoms.

論文

Developments of in-situ SEOP polarized $$^{3}$$He neutron spin filter in Japan

吉良 弘; 坂口 佳史; 奥 隆之; 鈴木 淳市; 中村 充孝; 新井 正敏; 遠藤 康夫; Chang, L.-J.; 加倉井 和久; 有本 靖*; et al.

Journal of Physics; Conference Series, 294, p.012014_1 - 012014_5, 2011/06

 被引用回数:8 パーセンタイル:4.31

The pulsed neutron source of J-PARC has started to operate in 2008 in Japan. To study structure of magnetic material and soft matters, polarized neutron scattering techniques are very important and powerful tools. It is urgently necessary for us to develop neutron spin polarizers for pulsed neutron scattering experiments. So we began the development of the in-situ SEOP system aiming to use it as a NSF for incident beam polarization and polarization analysis. In previous test performed by Ino et al., the $$^{3}$$He polarization reached 50% and not saturated yet. After that experiment, we began improving the SEOP system by installing the high power laser diode, the prism beam splitter and optimizing the beam-transform optics. By using this improved system, we performed the polarization test at BL10 in J-PRC and achieved the $$^{3}$$He polarization of 73%. We keep improving this in-situ SEOP system aiming to use it s an incident neutron polarizer at J-PARC.

論文

Applications of $$^{3}$$He neutron spin filters on the small-angle neutron scattering spectrometer SANS-J-II

坂口 佳史; 吉良 弘; 奥 隆之; 篠原 武尚; 鈴木 淳市; 酒井 健二; 中村 充孝; 相澤 一也; 新井 正敏; 能田 洋平; et al.

Journal of Physics; Conference Series, 294(1), p.012017_1 - 012017_7, 2011/06

 被引用回数:2 パーセンタイル:25.19

A polarized $$^{3}$$He neutron spin filter has been applied to polarization analysis on the small-angle neutron scattering spectrometer SANS-J-II at JRR-3. Measurements were taken on silver behenate, which has several coherent peaks in the small-angle region with a background of spin incoherent hydrogen scattering. Here we demonstrate that the coherent and spin incoherent scattering were successfully separated by the polarization analysis using the $$^{3}$$He spin filter on the instrument.

論文

Structure of glasses for $$^{3}$$He neutron spin filter cells

坂口 佳史; 吉良 弘; 奥 隆之; 篠原 武尚; 鈴木 淳市; 酒井 健二; 中村 充孝; 鈴谷 賢太郎; 相澤 一也; 新井 正敏; et al.

Journal of Physics; Conference Series, 294(1), p.012004_1 - 012004_7, 2011/06

 被引用回数:1 パーセンタイル:42.06

In spin-exchange optical pumping, there is unknown excess relaxation, called the X-factor, that limits attainable $$^{3}$$He polarization. It is known that the X-factor depends on the glass containers. Hence, it is expected that there are cell-to-cell variations in microscopic structure among the cells and that these variations affect the attainable $$^{3}$$He polarization. However, microscopic structure of the glasses for $$^{3}$$He neutron spin filters has not been clarified yet. In this paper, we have performed precise X-ray diffraction measurements for the glasses at SPring-8 using synchrotron radiation. The structural differences are observed between several types of glasses, and also, between the GE180 glass pieces with different thermal treatment. Based on the results, the structural influence on the performance of $$^{3}$$He neutron spin filters is discussed.

論文

Development and test of SEOP neutron spin filter in Japan

吉良 弘; 坂口 佳史; 奥 隆之; 鈴木 淳市; 中村 充孝; 新井 正敏; 加倉井 和久; 遠藤 康夫; 有本 靖*; 猪野 隆*; et al.

Physica B; Condensed Matter, 406(12), p.2433 - 2435, 2011/06

 被引用回数:8 パーセンタイル:55.78(Physics, Condensed Matter)

Polarized neutron scattering techniques are very important and powerful tools to study the fundamental structures of magnetic materials and soft matters. $$^{3}$$He has a very large absorption cross section for only neutrons in opposite spin state to that of the $$^{3}$$He nucleus. The scattering cross section of $$^{3}$$He is small. These two features allow nuclear spin polarized $$^{3}$$He gas to work as a NSF. Compared with other spin filters such as Heusler alloys and magnetic supermirrors, the $$^{3}$$He gas NSF have following advantages: it can polarize various energy of neutron such as cold, thermal and hot neutrons, it can work for broadband neutrons and it can be used for wide area and large divergence neutron beams. These characteristics of polarized $$^{3}$$He are convenient in use with J-PARC as NSF. We began the development of the on beam SEOP system aiming to use it s a NSF for incident beam polarisation and polarisation analysis. In this paper, we report the current development of SEOP system in Japan.

論文

Research on glass cells for $$^{3}$$He neutron spin filters

坂口 佳史; 吉良 弘; 奥 隆之; 篠原 武尚; 鈴木 淳市; 酒井 健二; 中村 充孝; 鈴谷 賢太郎; 相澤 一也; 新井 正敏; et al.

Physica B; Condensed Matter, 406(12), p.2443 - 2447, 2011/06

Polarized $$^{3}$$He neutron spin filters have attracted much attention because of their available wide energy range for polarizing neutrons and their large solid-angle. To use $$^{3}$$He neutron spin filters for the experiments, it is necessary to produce glass cells with good quality. For this purpose, we made research on the glass cells from several aspects. Firstly, we investigated on the microscopic structure for several glasses by means of X-ray diffraction measurement and tried to find a good measure of evaluating the quality of the cells in terms of their structure. Secondly, we investigated on the glass window, which the laser beam passes through for optical pumping. Thirdly, the cells should be optimized for the polarized neutron scattering experiments and the background from the cells needs to be evaluated. The scattered intensity from the cell in small-angle neutron scattering will also be presented.

論文

Research on glass cells for $$^{3}$$He neutron spin filters

坂口 佳史; 吉良 弘; 奥 隆之; 篠原 武尚; 鈴木 淳市; 酒井 健二; 中村 充孝; 鈴谷 賢太郎; 相澤 一也; 新井 正敏; et al.

Physica B; Condensed Matter, 406(12), p.2443 - 2447, 2011/06

 被引用回数:1 パーセンタイル:92.65(Physics, Condensed Matter)

Glass cells play an important role in polarized $$^{3}$$He neutron spin filters. To evaluate the scattering and absorption contribution from glass cells during neutron scattering experiments, we measured small-angle scattering and neutron transmission in GE180 and other glasses. To pursue the possibility of being a structural influence on $$^{3}$$He spin relaxation in GE180 glass cells, we performed precise X-ray diffraction measurement using synchrotron radiation at SPring-8. From these measurements, a structural difference was observed among GE180 glasses with different thermal treatments.

論文

Polarization-analyzed resonant inelastic X-ray scattering of the orbital excitations in KCuF$$_3$$

石井 賢司; 石原 純夫*; 村上 洋一*; 池内 和彦*; 葛下 かおり*; 稲見 俊哉; 大和田 謙二; 吉田 雅洋; Jarrige, I.; 多々見 央*; et al.

Physical Review B, 83(24), p.241101_1 - 241101_4, 2011/06

 被引用回数:18 パーセンタイル:30.21(Materials Science, Multidisciplinary)

We report a Cu $$K$$-edge resonant inelastic X-ray scattering (RIXS) study of orbital excitations in KCuF$$_3$$. By performing the polarization analysis of the scattered photons, we disclose that the excitation between the $$e_g$$ orbitals and the excitations from $$t_{2g}$$ to $$e_g$$ exhibit distinct polarization dependence. The polarization dependence of the respective excitations is interpreted based on a phenomenological consideration of the symmetry of the RIXS process that yields a necessary condition for observing the excitations. In addition, we show that the orbital excitations are dispersionless within our experimental resolution.

論文

Characterization of glasses for $$^{3}$$He neutron spin filter cells

坂口 佳史; 吉良 弘; 奥 隆之; 篠原 武尚; 鈴木 淳市; 酒井 健二; 中村 充孝; 鈴谷 賢太郎; 新井 正敏; 武田 全康; et al.

Nuclear Instruments and Methods in Physics Research A, 634(1, Suppl.), p.S122 - S125, 2011/04

Polarized $$^{3}$$He neutron spin filters are promising neutron polarizers in polarized neutron scattering experiments at facilities with two-dimensional detectors and pulsed neutron source. Although they are now operational at several institutions, it is still desired to be developed. Among required factors for the development, the study on the glasses in the filters is one of the important issues. In this paper, we report our recent investigation on the glass cells such as X-ray diffraction measurements and the measurements of the degree of circular polarization of the transmitted laser light through the glass window in the filter.

論文

Resonant inelastic X-ray scattering of La$$_2$$Cu$$_{0.95}$$Ni$$_{0.05}$$O$$_4$$

石井 賢司; 池内 和彦*; Jarrige, I.; 水木 純一郎; 平賀 晴弘*; 山田 和芳*; 筒井 健二; 遠山 貴己*; 前川 禎通*; 遠藤 康夫*; et al.

Physica C, 470(Suppl.1), p.S155 - S157, 2010/12

 パーセンタイル:100(Physics, Applied)

Substitution of a specific element for a component is often used to elucidate its role in the superconductors. For a complete understanding of the substitution effect not only on the superconductivity but also on the electronic states, element-selective experiments are required. In this respect, resonant inelastic X-ray scattering (RIXS) has proven to be a powerful experimental technique enabling element-selective diagnosis of charge excitations. By tuning the incident photon energy to a given absorption edge of the element, the excitations involving the element are resonantly enhanced. In addition, RIXS has the advantage that momentum dependence can be measured. Using RIXS, we have measured the electronic excitations at the substituting sites in La$$_2$$Cu$$_{0.95}$$Ni$$_{0.05}$$O$$_4$$ and La$$_2$$Ni$$_{0.95}$$Cu$$_{0.05}$$O$$_4$$. Near the absorption edge of the substituting element, namely the Ni $$K$$-edge for La$$_2$$Cu$$_{0.95}$$Ni$$_{0.05}$$O$$_4$$ and the Cu $$K$$-edge for La$$_2$$Ni$$_{0.95}$$Cu$$_{0.05}$$O$$_4$$, charge transfer excitations from the 2$$p$$ level of neighboring oxygen to the upper Hubbard band of the substituted Ni/Cu are observed. Experimental spectra are qualitatively reproduced by a theoretical calculation based on a $$d$$-$$p$$ model.

論文

Temperature dependence of the electronic structure of Sr$$_{14}$$Cu$$_{24}$$O$$_{41}$$ studied by resonant inelastic X-ray scattering

吉田 雅洋; 石井 賢司; 池内 和彦*; Jarrige, I.; 村上 洋一*; 水木 純一郎; 筒井 健二; 遠山 貴己*; 前川 禎通*; 工藤 一貴*; et al.

Physica C, 470(Suppl.1), p.S145 - S146, 2010/12

 被引用回数:4 パーセンタイル:73.14(Physics, Applied)

Sr$$_{14-x}$$Ca$$_x$$Cu$$_{24}$$O$$_{41}$$ (SCCO), which is composed of two-leg ladders and edge-sharing chains, is the first superconducting cuprate without CuO$$_2$$ planes. By substituting Ca for Sr, holes are transferred from the chains to the ladders. It was recently shown that charge ordering (CO) along the leg direction in the ladder occurs at $$x=0$$ and the periodicity is five times the unit length along the c axis. In order to investigate the electronic excitations associated with the CO, we carried out resonant inelastic X-ray scattering (RIXS) experiments for SCCO ($$x=0,6$$). Cu-$$K$$ RIXS can directly probe the momentum-dependent electronic excitations related to the Cu site, which are resonantly enhanced by tuning the incident photon energy to the Cu $$K$$-edge. We measured the q dependence of the intraband excitations, which is associated with the dynamics of doped holes in the Zhang-Rice singlet band. The intensity is enhanced at the momentum $${bf q}=(q_{rm rung},q_{rm leg})=(0,2pi/5)$$ corresponding to the periodicity of the CO in $$x=0$$, while the temperature dependence of the enhancement is different for $$x=0$$ and $$x=6$$. We discuss the relationship between our experimental results and the occurrence of the CO.

論文

Nematic-to-smectic transition of magnetic texture in conical state

武田 全康; 遠藤 康夫; 加倉井 和久; 小野瀬 佳文*; 鈴木 淳市; 十倉 好紀*

Journal of the Physical Society of Japan, 78(9), p.093704_1 - 093704_4, 2009/09

 被引用回数:14 パーセンタイル:31.64(Physics, Multidisciplinary)

Fe$$_{0.7}$$Co$$_{0.3}$$Siの長距離磁気秩序状態が示す複雑な磁気相転移の様子を低温,外部磁場下で中性子小角散乱によって調べた。リング状,三日月状,ぼやけた回折線など、温度と外部磁場によってさまざまな散乱パターンが現れた。この結果は、磁化を液晶の配向ベクトルとみなすことで、液晶で見られる相転移との類似性を明らかにした。

論文

Momentum-resolved charge excitations in high-$$T$$$$_{rm c}$$ cuprates studied by resonant inelastic X-ray scattering

石井 賢司; Hoesch, M.*; 稲見 俊哉; 葛下 かおり*; 大和田 謙二; 坪田 雅己; 村上 洋一; 水木 純一郎; 遠藤 康夫; 筒井 健二*; et al.

Journal of Physics and Chemistry of Solids, 69(12), p.3118 - 3124, 2008/12

 被引用回数:3 パーセンタイル:78.44(Chemistry, Multidisciplinary)

Resonant inelastic X-ray scattering (RIXS) in the hard X-ray regime is a new spectroscopic technique to measure electronic excitations utilizing brilliant synchrotron radiation. It has the great advantage that the momentum dependence can be measured unlike conventional optical methods. As inelastic neutron scattering gives spin or lattice dynamics, inelastic X-ray scattering can be a tool to measure charge dynamics in solids through the coupling of photon to the charge of the electron. Here, I would like to present our RIXS studies on high-$$T_c$$ cuprates and related materials which were performed in close collaboration with theorists. In doped Mott insulators, an interband excitation across the Mott gap and an intraband excitation below the gap are observed in the low energy region of RIXS spectra. Momentum and carrier-doping dependence of the excitations will be discussed.

論文

Momentum-dependent charge excitations of a two-leg ladder; Resonant inelastic X-ray scattering of (La,Sr,Ca)$$_{14}$$Cu$$_{24}$$O$$_{41}$$

石井 賢司; 筒井 健二*; 遠山 貴己*; 稲見 俊哉; 水木 純一郎; 村上 洋一*; 遠藤 康夫*; 前川 禎通*; 工藤 一貴*; 小池 洋二*; et al.

Physical Review B, 76(4), p.045124_1 - 045124_7, 2007/07

 被引用回数:18 パーセンタイル:33.76(Materials Science, Multidisciplinary)

(La,Sr,Ca)$$_{14}$$Cu$$_{24}$$O$$_{41}$$は銅酸化物高温超伝導体との関連で注目されている物質である。ほとんどの銅酸化物超伝導体の共通ユニットであるCuO$$_2$$面を持たないにもかかわらず、Sr$$_{0.4}$$Ca$$_{13.6}$$Cu$$_{24}$$O$$_{41}$$は高圧下で超伝導体となる。銅の$$K$$吸収端で行った(La,Sr,Ca)$$_{14}$$Cu$$_{24}$$O$$_{41}$$の共鳴非弾性X線散乱の結果について報告する。モットギャップを越えるバンド間励起とギャップ内に現れるバンド内励起の運動量依存性がホール濃度に対してどのように変化するかに注目する。得られた実験結果は理論の予想と一致している。

論文

Momentum dependence of Mott gap excitations in optimally doped YBa$$_2$$Cu$$_3$$O$$_{7-delta}$$ studied by resonant inelastic X-ray scattering

石井 賢司; 筒井 健二*; 遠藤 康夫*; 遠山 貴己*; 葛下 かおり; 稲見 俊哉; 大和田 謙二; 前川 禎通*; 増井 孝彦*; 田島 節子*; et al.

AIP Conference Proceedings 850, p.445 - 446, 2006/09

共鳴非弾性X線散乱により最適ドープにある高温超伝導体YBa$$_2$$Cu$$_3$$O$$_{7-delta}$$($$T_{c}$$=93K)の研究を行った。非双晶の結晶を用いることでab面内における異方的なスペクトルを観測することができた。一次元CuO鎖からの励起は$$b^{*}$$方向のゾーン端で2eVあたりに強度が増大するのに対し、1.5-4eVにあるCuO$$_2$$面からの励起は運動量にほとんど依存しない。一次元及び二次元ハバードモデルに基づく理論計算では、異なったクーロンエネルギーを取り入れることで、観測したスペクトルを再現することができる。CuO鎖のモットギャップの大きさはCuO$$_2$$面に比べて小さいことが明らかになった。

論文

Doping Momentum dependence of charge dynamics in Nd$$_{2-x}$$Ce$$_{x}$$CuO$$_4$$ (x=0, 0.075, and 0.15) studied by Resonant inelastic X-ray scattering

石井 賢司; 筒井 健二*; 遠藤 康夫*; 遠山 貴己*; 前川 禎通*; Hoesch, M.; 葛下 かおり; 稲見 俊哉; 坪田 雅己; 山田 和芳*; et al.

AIP Conference Proceedings 850, p.403 - 404, 2006/09

共鳴非弾性X線散乱(RIXS)による電子ドープ型高温超伝導体Nd$$_{1.85}$$Ce$$_{0.15}$$CuO$$_4$$の電荷励起の研究について報告する。低エネルギーにある電荷励起を観測できるように実験条件を適切にあわせることで、フェルミエネルギーを越えるバンド内励起とバンド間励起を初めて分離することができた。バンド内励起では幅に運動量($${mathbf q}$$)依存があるような分散関係が現れるのに対し、バンド間励起では強度がゾーン中央で2eV付近に集中する。これらの実験結果は、ハバードモデルに基づくRIXSスペクトルの理論的な計算と一致している。

論文

Electronic excitations in hole-doped La$$_{1-x}$$Sr$$_{x}$$MnO$$_{3}$$ studied by resonant inelastic X-ray scattering

石井 賢司; 稲見 俊哉; 大和田 謙二; 葛下 かおり; 水木 純一郎; 村上 洋一; 石原 純夫*; 遠藤 康夫*; 前川 禎通*; 廣田 和馬*; et al.

Journal of Physics and Chemistry of Solids, 66(12), p.2157 - 2162, 2005/12

 パーセンタイル:100(Chemistry, Multidisciplinary)

La$$_{1-x}$$Sr$$_{x}$$MnO$$_{3}$$(x=0.2,0.4)についてMnのK吸収端での共鳴X線非弾性散乱法により電子励起の研究を行った。ホールドープで金属化したことによるギャップの消失がLa$$_{0.6}$$Sr$$_{0.4}$$MnO$$_{3}$$において観測できた。また、温度により金属絶縁体転移を示すLa$$_{0.8}$$Sr$$_{0.2}$$MnO$$_{3}$$では、散乱強度の温度変化に顕著な異方性が見られており、これはMn酸化物に特有の軌道自由度を反映した異方的な電子状態の変化を捉えたものと考えられる。

論文

Momentum dependence of charge excitations in the electron-doped superconductor Nd$$_{1.85}$$Ce$$_{0.15}$$CuO$$_4$$; A Resonant inelastic X-ray scattering study

石井 賢司; 筒井 健二*; 遠藤 康夫*; 遠山 貴己*; 前川 禎通*; Hoesch, M.; 葛下 かおり; 坪田 雅己; 稲見 俊哉; 水木 純一郎; et al.

Physical Review Letters, 94(20), p.207003_1 - 207003_4, 2005/05

 被引用回数:62 パーセンタイル:10.34(Physics, Multidisciplinary)

共鳴非弾性X線散乱(RIXS)による電子ドープ型高温超伝導体Nd$$_{1.85}$$Ce$$_{0.15}$$CuO$$_4$$の電荷励起の研究について報告する。低エネルギーにある電荷励起を観測できるように実験条件を適切にあわせることで、フェルミエネルギーを越えるバンド内励起とバンド間励起を初めて分離することができた。バンド内励起では幅に運動量($${mathbf q}$$)依存があるような分散関係が現れるのに対し、バンド間励起では強度がゾーン中央で2eV付近に集中する。これらの実験結果は、ハバードモデルに基づくRIXSスペクトルの理論的な計算と一致している。

論文

Mott gap excitations in twin-free YBa$$_2$$Cu$$_3$$O$$_{7-delta}$$ ($$T_{c}$$ = 93 K) studied by resonant inelastic X-ray scattering

石井 賢司; 筒井 健二*; 遠藤 康夫*; 遠山 貴己*; 葛下 かおり; 稲見 俊哉; 大和田 謙二; 前川 禎通*; 増井 孝彦*; 田島 節子*; et al.

Physical Review Letters, 94(18), p.187002_1 - 187002_4, 2005/05

 被引用回数:37 パーセンタイル:17.57(Physics, Multidisciplinary)

共鳴非弾性X線散乱により最適ドープにある高温超伝導体YBa$$_2$$Cu$$_3$$O$$_{7-delta}$$($$T_{c}$$=93K)の研究を行った。非双晶の結晶を用いることでab面内における異方的なスペクトルを観測することができた。一次元CuO鎖からの励起は$$b^{*}$$方向のゾーン端で2eVあたりに強度が増大するのに対し、1.5-4eVにあるCuO$$_2$$面からの励起は運動量にほとんど依存しない。一次元及び二次元ハバードモデルに基づく理論計算では、異なったクーロンエネルギーを取り入れることで、観測したスペクトルを再現することができる。CuO鎖のモットギャップの大きさはCuO$$_2$$面に比べて小さいことが明らかになった。

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