検索対象:     
報告書番号:
※ 半角英数字
 年 ~ 
 年
検索結果: 97 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 ...

選択した検索結果をダウンロード

論文

Effect of inner wall cracking on the cavitation bubble formation in the mercury spallation target at J-PARC

有吉 玄; 猿田 晃一; 粉川 広行; 二川 正敏; 前野 航希*; Li, Y.*; 筒井 喜平*

Proceedings of 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20) (Internet), p.1407 - 1420, 2023/08

水銀を核破砕標的とするパルス中性子源では、陽子線励起圧力波による標的容器のキャビテーション損傷が問題視されている。このような損傷の抑制手法として、旋回流式気泡注入器で水銀中に微小He気泡を混合し、その圧縮性効果を用いる手法や、標的容器内側に流路壁を追加した二重壁流路構造を設ける手法が採用されている。本研究では、二重壁流路体系において内壁部に生じ得るキャビテーション由来の貫通損傷を標的容器外部から検出する異常診断技術の確立を目指す。本論文では、貫通損傷が生じた場合の水銀流れを有限要素法に基づく流動解析で明らかにし、流体励起・音響振動の観点から、損傷の影響を評価した結果を報告する。

論文

Investigation of the phonon dispersion associated with superlattice reflections in the BiS$$_{2}$$-based superconductor LaBiS$$_{2}$$O$$_{0.5}$$F$$_{0.5}$$

玉造 博夢; 長谷川 巧*; 佐賀山 基*; 水牧 仁一朗*; 村上 洋一*; 梶谷 丈*; 東中 隆二*; 松田 達磨*; 青木 勇二*; 筒井 智嗣*

Physical Review B, 107(2), p.024303_1 - 024303_8, 2023/01

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

The phonon dispersion of a BiS$$_{2}$$-based superconductor LaBiS$$_{2}$$O$$_{0.5}$$F$$_{0.5}$$ is investigated by first-principles calculations and inelastic X-ray scattering experiments. The origin of superlattice (SL) reflections arising from transverse-type lattice modulation, which were recently reported in [J. Kajitani $textit{et al}$., J. Phys. Soc. Jpn. ${bf 90}$, 103601 (2021)], is discussed in terms of lattice dynamics. Our first-principles calculations of phonon dispersion and the Fermi surfaces (FSs) demonstrate that the phonon mode corresponding to the transverse-type lattice modulation is unstable, and the propagation vector corresponding to the SL reflections is close to the FS nesting vector, which suggests that the phonon softening originates from the FS nesting. Against these calculated expectations, measured phonon dispersion in LaBiS$$_{2}$$O$$_{0.5}$$F$$_{0.5}$$ along the Z-A direction, where the SL point is located, shows no remarkable temperature dependence, and there are no steeply declining branches accompanied with a softening around the SL point. Based on these results, we discuss the two possibilities for the transverse lattice modulation in LaBiS$$_{2}$$O$$_{0.5}$$F$$_{0.5}$$: the order-disorder type structural transition and the displacive structural transition with an overdamped mode, for both of which the local structure distortion or the short range correlation within the BiS$$_{2}$$ plane would be essential.

論文

Phonon softening in Lu(Pt$$_{1-x}$$Pd$$_x$$)$$_2$$In close to a zero-temperature structural instability

Gruner, T.*; Lucas, S.*; Geibel, C.*; 金子 耕士; 筒井 智嗣*; Schmalzl, K.*; Stockert, O.*

Physical Review B, 106(11), p.115142_1 - 115142_6, 2022/09

 被引用回数:1 パーセンタイル:18.86(Materials Science, Multidisciplinary)

The disappearance of a charge-density-wave (CDW) transition in Lu(Pt$$_{1-x}$$Pd$$_x$$)$$_2$$In is thought to be closely linked to a maximum of the superconducting transition temperature in the system. We studied the superstructure and the phonon softening in Lu(Pt$$_{0.5}$$Pd$$_{0.5}$$)$$_2$$In by means of neutron and high-resolution inelastic X-ray scattering. A full phonon softening at $$q_{textrm{CDW}}$$ = (0.5, 0.5, 0) with the appearance of superstructure peaks could be clearly identified. The large tail of the superstructure intensity above the CDW transition indicates the importance of critical fluctuations.

論文

Sm valence determination of Sm-based intermetallics using $$^{149}$$Sm M$"{o}$ssbauer and Sm L$$_{rm III}$$-edge X-ray absorption spectroscopies

筒井 智嗣; 東中 隆二*; 中村 頼人*; 藤原 孝将*; 中村 仁*; 小林 義男*; 伊藤 孝; 依田 芳卓*; 加藤 和男*; 新田 清文*; et al.

Hyperfine Interactions, 242(1), p.32_1 - 32_10, 2021/12

 被引用回数:1 パーセンタイル:84.42

$$^{149}$$Sm synchrotron-radiation-based M$"{o}$ssbauer spectroscopy was performed in Sm-based intermetallics having a cubic crystal structure, Sm$$_{3}Tr_{4}$$Ge$$_{13}$$, SmB$$_{6}$$, SmBe$$_{13}$$, and Sm$$Tr_{2}$$Al$$_{20}$$ ($$Tr$$ = transition metals). In spite of the difference of the local structure around the Sm sites, the observed M$"{o}$ssbauer spectra consist of a single line at 300 K. On the other hand, Sm L$$_{rm III}$$-edge X-ray absorption spectra consist of two components, suggesting Sm$$^{2+}$$ and Sm$$^{3+}$$ states. Difference of the number of the spectral components between the M$"{o}$ssbauer spectroscopy and X-ray absorption spectroscopy is caused by the difference of the time window in the scattering process of these measurements. Correlation between the isomer shifts in the M$"{o}$ssbauer spectroscopy and average Sm valence states estimated from the X-ray absorption spectroscopy exhibits a linear correlation.

論文

Lattice dynamics in CePd$$_2$$Al$$_2$$ and LaPd$$_2$$Al$$_2$$

Dole$v{z}$al, P.*; Cejpek, P.*; 筒井 智嗣*; 金子 耕士; Legut, D.*; Carva, K.*; Javorsk$'y$, P.*

Scientific Reports (Internet), 11(1), p.20878_1 - 20878_10, 2021/10

 被引用回数:0 パーセンタイル:0(Multidisciplinary Sciences)

The interaction between phonons and 4f electrons, which is forming a new quantum state (quasi-bound state) beyond Born-Oppenheimer approximation, is very prominent and lattice dynamics plays here a key role. There is only a small number of compounds in which the experimental observation suggest such a scenario. One of these compounds is CePd$$_2$$Al$$_2$$. The inelastic X-ray scattering technique was used for mapping the phonon modes at X and Z points as well as in L and D directions, where the symmetry analysis of phonon modes was performed. The measured spectra are compared with the theoretical calculation, showing very good agreement. The results are discussed with respect to the magneto-elastic interaction. The phonon mode symmetry A1g was found to be unaffected by the interaction, which is in contrast to previous assumptions.

論文

Nature of structural instabilities in superconducting Sr$$_3$$Ir$$_4$$Sn$$_{13}$$

金子 耕士; Cheung, Y. W.*; Hu, Y.*; 今井 正樹*; 谷奥 泰明*; 金川 響*; 村川 譲一*; 森山 広大*; Zhang, W.*; Lai, K. T.*; et al.

JPS Conference Proceedings (Internet), 30, p.011032_1 - 011032_6, 2020/03

A quantum critical point appears as a second-order phase transition which takes place at zero temperature. In contrast to heavy-fermion systems in which magnetism often plays a vital role, recent studies revealed that structural instabilities can drive a system to a quantum critical point as well. In quasi-skutterudite (Ca,Sr)$$_3T_4$$Sn$$_{13}$$ ($$T$$=Rh, Ir), Sr$$_3$$Ir$$_4$$Sn$$_{13}$$ exhibits superconductivity around $$T_{rm sc}$$$${sim}$$5 K and a structural transition at $$T^*{simeq}$$147 K. Applying physical or chemical pressure on Sr$$_3$$Ir$$_4$$Sn$$_{13}$$ suppresses $$T^*$$ rapidly, and a quasi-linear $$T$$ dependence of electrical resistivity, signature of non-Fermi liquid behavior, was observed where $$T^*$$ extrapolates to 0 K. The isomorphs (Ca$$_x$$Sr$$_{1-x}$$)$$_3$$Rh$$_4$$Sn$$_{13}$$ exhibits similar behavior, where the criticality can be reached by $$x{sim}$$0.9 without external pressure. Neutron scattering experiments in Sr$$_3$$Ir$$_4$$Sn$$_{13}$$ evidences the second order nature of the structural transition at $$T^*$$ by the observation of a continuous evolution of superlattice peak below $$T^*$$ and a gradual increase of critical scattering upon approaching to $$T^*$$ by cooling. Increase of $$x$$ in (Ca$$_x$$Sr$$_{1-x}$$)$$_3$$Rh$$_4$$Sn$$_{13}$$ toward the quantum critical point leads to the systematic variation of the critical exponents of the order parameter. In addition, this substitution induces the phonon softening around the M point towards zero energy revealed by inelastic X-ray scattering experiment. We will present systematic variations in both elastic and inelastic channels upon approaching to the quantum critical point.

論文

Evidence of a structural quantum critical point in (Ca$$_x$$Sr$$_{1-x}$$)$$_3$$Rh$$_4$$Sn$$_{13}$$ from a lattice dynamics study

Cheung, Y. W.*; Hu, Y. J.*; 今井 正樹*; 谷奥 泰明*; 金川 響*; 村川 譲一*; 森山 広大*; Zhang, W.*; Lai, K. T.*; 吉村 一良*; et al.

Physical Review B, 98(16), p.161103_1 - 161103_5, 2018/10

 被引用回数:19 パーセンタイル:67.65(Materials Science, Multidisciplinary)

Approaching a quantum critical point has been an effective route to stabilize superconductivity. While the role of magnetic QCPs has been extensively discussed, similar exploration of a structural QCP is scarce. Using inelastic X-ray scattering, we examine the phonon spectrum of the nonmagnetic quasi-skutterudite (Ca$$_x$$Sr$$_{1-x}$$)$$_3$$Rh$$_4$$Sn$$_{13}$$, which represents a precious system to explore the interplay between structural instabilities and superconductivity by tuning the Ca concentration x. We unambiguously detect the softening of phonon modes around the M point on cooling towards the structural transition. Intriguingly, at x = 0:85, the soft mode energy squared at the M point extrapolates to zero at -5.7 K, providing the first compelling microscopic evidence of a structural QCP in (Ca$$_x$$Sr$$_{1-x}$$)$$_3$$Rh$$_4$$Sn$$_{13}$$. The enhanced phonon density-of-states at low energy provides the essential ingredient for realizing strong-coupling superconductivity near the structural QCP.

論文

Effect of $$B$$-site randomness on the antiferroelectric/relaxor nature of the ground state; Diffuse and inelastic X-ray scattering study of Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_3$$

大和田 謙二*; 塚田 慎也*; 福田 竜生; 筒井 智嗣*; Baron, A. Q. R.*; 水木 純一郎*; 大和 英弘*; 安田 直彦*; 寺内 暉*

Physical Review B, 98(5), p.054106_1 - 054106_10, 2018/08

 被引用回数:3 パーセンタイル:15.79(Materials Science, Multidisciplinary)

The effect of $$B$$-site randomness on the antiferroelectric/relaxor nature of the ground state was investigated by studying diffuse and inelastic X-ray scattering from ordered and disordered Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_3$$ (O- and D-PIN) single crystals. The diffuse scattering measurement of O-PIN (antiferroelectric at $$T<T_N$$) shows the existence of ferroelectrically interactive local polarization above $$T_N$$. Inelastic X-ray scattering shows that the transverse-acoustic (TA) and transverse-optic (TO) modes are dominant at $$Tsim$$800 K, while the central peak (CP) and TA modes are coupled and majorly contribute to the critical behavior of the diffuse scattering at $$T_N$$. Upon these results, the $$B$$-site randomness is discussed in terms of suppressing the antiferroelectric instability and enhancing the polarization fluctuation.

論文

Inelastic X-ray scattering of $$RT$$Al$$_3$$ ($$R$$ = La, Ce, $$T$$ = Cu, Au)

筒井 智嗣*; 金子 耕士; Pospisil, J.; 芳賀 芳範

Physica B; Condensed Matter, 536, p.24 - 27, 2018/05

 被引用回数:3 パーセンタイル:15.79(Physics, Condensed Matter)

Inelastic X-ray scattering (IXS) experiments of RTAl$$_3$$ ($$R$$ = La Ce, $$T$$ = Cu, Au) were carried out at 300 and 5.5 K. The spectra between LaCuAl$$_3$$ and CeCuAl$$_3$$ (LaAuAl$$_3$$ and CeAuAl$$_3$$) are nearly identical at both temperatures except for temperature factors such as temperature dependence of Bose factor in IXS spectra and effect on thermal expansion. This means that no evident temperature dependence of IXS spectra was observed in CeTAl$$_3$$ ($$T$$ = Cu, Au).

論文

Second-order structural transition in (Ca$$_{0.5}$$Sr$$_{0.5}$$)$$_3$$Rh$$_4$$Sn$$_{13}$$

Cheung, Y. W.*; Hu, Y. J.*; Goh, S. K.*; 金子 耕士; 筒井 智嗣; Logg, P. W.*; Grosche, F. M.*; 金川 響*; 谷奥 泰明*; 今井 正樹*; et al.

Journal of Physics; Conference Series, 807(3), p.032002_1 - 032002_4, 2017/04

BB2016-0329.pdf:0.86MB

 被引用回数:5 パーセンタイル:83.85

(Ca$$_{0.5}$$Sr$$_{0.5}$$)$$_3$$Rh$$_4$$Sn$$_{13}$$ is a member of the substitution series (Ca$$_{x}$$Sr$$_{1-x}$$)$$_3$$Rh$$_4$$Sn$$_{13}$$ which has recently been argued to feature a structural quantum critical point at $$x_c$$ = 0.9. In the stoichiometric compound Sr$$_{3}$$Rh$$_{4}$$Sn$$_{13}$$, the structural transition at $$T^*$$ $$approx$$ 138 K has been shown to be a second-order phase transition. Moving towards xc, we examine the character of the structural transition in (Ca$$_{0.5}$$Sr$$_{0.5}$$)$$_3$$Rh$$_4$$Sn$$_{13}$$ (i.e. $$x$$ = 0.5, $$T^*$$ $$approx$$ 55 K) using electrical resistivity, heat capacity and X-ray scattering. The absence of the thermal hysteresis in specific heat around $$T^*$$, and the continuous evolution of the superlattice reflection detected by X-ray diffraction are consistent with the scenario that the structural transition associated with a modulation vector $$q$$ = (0.5, 0.5, 0) in (Ca$$_{0.5}$$Sr$$_{0.5}$$)$$_3$$Rh$$_4$$Sn$$_{13}$$ remains second-order on approaching the quantum critical point.

論文

Impurity effects in the microscopic elastic properties of polycrystalline Mg-Zn-Y alloys with a synchronised long-period stacking ordered phase

細川 伸也*; 木村 耕治*; 山崎 倫昭*; 河村 能人*; 吉田 亨次*; 乾 雅祝*; 筒井 智嗣*; Baron, A. Q. R.*; 川北 至信; 伊藤 晋一*

Journal of Alloys and Compounds, 695, p.426 - 432, 2017/02

 被引用回数:3 パーセンタイル:16.87(Chemistry, Physical)

Inelastic X-ray scattering (IXS) was performed on polycrystalline Mg$$_{97}$$Zn$$_1$$Y$$_2$$ and Mg$$_{85}$$Zn$$_6$$Y$$_9$$ alloys with synchronized long-period stacking ordered (LPSO) phase for investigating the impurity effects in the microscopic elastic properties. Inelastic neutron scattering (INS) was also carried out on the former alloy. LA modes were clearly observed in the IXS spectra of both the LPSO alloys, while TA modes can mainly be detected in the second Brillouin zone. Broader inelastic signals and larger quasielastic peaks are characteristic due to the phonon scattering by the Zn/Y impurities. Only the TA excitation energies increase by adding the impurities, which indicates a harder stiffness of the bond angles relating to the L1$$_2$$-type clusters in the LPSO alloys. New dispersion-less excitation modes are observed at about 10 meV by adding the Zn/Y impurities. By comparing with the INS data, the contributions of the impurities to these excitations are discussed using differences in the scattering cross-sections between neutrons and X-rays.

論文

Numerical simulation on molten metal collision behavior using SPH method combined with fractal analysis on morphology of stacking pattern

二川 正敏; 筒井 喜平*; 粉川 広行; 直江 崇

Key Engineering Materials, 715, p.203 - 209, 2016/11

世界的関心の寄せられる様々な科学技術を展開しうる大強度陽子加速器施設では、加速器から出射されるMW級の大強度陽子線に耐えつつ、効率よく2次粒子を生成する標的が要求される。固体金属標的は、大強度の陽子線が入射することによって非常に高い熱流束が負荷され、場合によっては瞬時に溶融することが推測される。実際、J-PARC(Japan Proton Accelerator Research Complex)では、金の固体標的が局所的に溶融し、溶融金が噴出する事象が生じた。溶融金ジェットは真空を隔てるフランジ板に衝突して飛散すると共に、一部はフランジ板に付着した。この挙動を粒子法による数値解析で再現し、フランジ板上の付着痕の様相と衝突速度との相関について、フラクタル解析を導入して定量評価を試みた。その結果、フラクタル次元は衝突速度に依存し、局所衝撃力や飛散挙動を評価する指標として有効であることが分かった。

論文

Effect of magnetism on lattice dynamics in SrFe$$_2$$As$$_2$$ 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

 被引用回数:7 パーセンタイル:34.33(Materials Science, Multidisciplinary)

Phonon spectra of detwinned SrFe$$_2$$As$$_2$$ 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$$_N$$, and the measured phonon linewidth, we set a lower bound on the mean magnetic fluctuation frequency above T$$_N$$ at 210 K.

論文

M$"o$ssbauer spectroscopy of actinide compounds

筒井 智嗣

M$"o$ssbauer Effect Reference and Data Journal, 38(4), p.105 - 111, 2015/06

アクチノイド化合物のメスバウアー分光は日本でも海外でも実施可能な施設は限られる。日本におけるアクチノイドのメスバウアー分光の研究は1990年代に先端基礎研究センターにおいて開始された。本稿では、1996年に先端基礎研究センターで開始されたU-238メスバウアー分光及び東北大学金属材料研究所で開始されたネプツニウム金属間化合物のメスバウアー分光に関する研究成果について纏めた。また、これらのアクチノイドのメスバウアー分光の研究成果のレビューを行うとともに、その発展に寄与された故那須三郎阪大名誉教授の貢献に関してまとめたものである。

論文

X-ray absorption spectroscopy and novel electronic properties in heavy fermion compounds YbT$$_{2}$$Zn$$_{20}$$ (T: Rh and Ir)

本多 史憲*; 広瀬 雄介*; 三宅 厚志*; 水牧 仁一朗*; 河村 直己*; 筒井 智嗣*; 綿貫 徹; 渡辺 真仁*; 竹内 徹也*; 摂待 力生*; et al.

Journal of Physics; Conference Series, 592(1), p.012021_1 - 012021_5, 2015/03

 被引用回数:2 パーセンタイル:61.05

重い電子系化合物YbT$$_{2}$$Zn$$_{20}$$(T: Rh and Ir)について、X線吸収分光法によりYb価数観察を行った。いずれの化合物でもYb価数は温度依存性を示し、約100K以下で冷却とともにYb価数が減少する変化が見られた。これは、同型化合物であるYbCo$$_{2}$$Zn$$_{20}$$において温度依存性が見られないこととは対照的な結果である。

論文

Zirconia membrane ECP electrode for water chemistry experiments in the JMTR

塙 悟史; 端 邦樹; 柴田 晃; 知見 康弘; 笠原 茂樹; 筒井 伸行*; 岩瀬 彰宏*; 西山 裕孝

Proceedings of 2014 Nuclear Plant Chemistry Conference (NPC 2014) (USB Flash Drive), 9 Pages, 2014/10

腐食電位(ECP)センサーは照射下における材料の腐食環境を測定できる唯一の計測器である。高い耐久性を有するECPセンサーをJMTRで実施する水化学実験で使用するために、ジルコニア隔膜型ECPセンサーを開発した。ジルコニア及び金属筐体の材料選定とそれらの最適な組み合わせを検討し、ジルコニアにはイットリア安定化ジルコニアを、金属筐体には42合金を採用した。また、ジルコニア/金属の接合部への欠陥の発生を防止するために金属筐体の構造最適化を図った。ECPセンサーの性能はオートクレーブで評価し、理論的に求まる電位に準ずる電極電位を示すとともに電極電位は水質環境の変化に対しても安定であることを確認した。また、ECPセンサーへの照射影響としてジルコニアへの照射誘起伝導の影響を評価し、ジルコニアに照射誘起伝導は生じるもののECPセンサー機能には影響を及ぼさないことを示した。

論文

Anharmonic Pr guest modes in Pr(Os$$_{1-x}$$Ru$$_x$$)$$_4$$Sb$$_{12}$$ investigated by inelastic X-ray scattering

筒井 智嗣; 金子 耕士; 宮崎 亮一*; 東中 隆二*; 青木 勇二*; 小林 理気*; 脇本 秀一; Baron, A. Q. R.*; 菅原 仁*; 佐藤 英行*

JPS Conference Proceedings (Internet), 3, p.011060_1 - 011060_5, 2014/06

We have investigated the Ru/Os concentration dependence of the Pr guest mode in Pr(Os$$_{1-x}$$Ru$$_x$$)$$_4$$Sb$$_{12}$$ and its variation with temperature. The Pr guest mode at 3.2 meV in PrOs$$_4$$Sb$$_{12}$$ at the N point linearly shifts to a higher energy with the substitution of Ru into the Os site. The energy of the Pr guest mode decreases with decreasing temperature for all compositions, indicating the presence of an anharmonic potential at the Pr site. The slope of the temperature dependence of the guest mode energy is steeper for pure PrOs$$_4$$Sb$$_{12}$$ than for the other Pr(Os$$_{1-x}$$Ru$$_x$$)$$_4$$Sb$$_{12}$$ compounds we measured. The present results imply the importance of the transition metal in determining anharmonicity in Pr(Os$$_{1-x}$$Ru$$_x$$)$$_4$$Sb$$_{12}$$.

論文

Multi-spin-state dynamics during insulator-metal crossover in LaCoO$$_3$$

土居 篤典*; 藤岡 淳*; 福田 竜生; 筒井 智嗣*; 奥山 大輔*; 田口 康二郎*; 有馬 孝尚*; Baron, A. Q. R.*; 十倉 好紀*

Physical Review B, 90(8), p.081109_1 - 081109_4, 2014/01

 被引用回数:17 パーセンタイル:58.59(Materials Science, Multidisciplinary)

The phonon dynamics of spin-state crossover for perovskite LaCoO$$_3$$ was investigated using infrared and inelastic X-ray spectroscopy. We observed that the Co-O bond stretching phonons couples to the thermally excited spin-state. The momentum dispersion of the optical mode is anomalously dispersionless (less than 3 meV), and this supports the spin-state disproportionation scenario. The steep enhancement of spin-state fluctuation compared to the charge gap suggests the density dependent spin state disproportionation; a simple low spin (LS)/high spin (HS)- or LS/intermediate spin (IS)-state disproportionation is realized at the initial stage with dilute HS- (or IS-) state density, while the complex spin-state disproportionation involving all of the LS-, IS- and HS-state is formed when the density of HS- (or IS-) state is enhanced.

論文

Temperature and magnetic field dependent Yb valence in YbRh$$_2$$Si$$_2$$ observed by X-ray absorption spectroscopy

中井 裕人*; 海老原 孝雄*; 筒井 智嗣*; 水牧 仁一朗*; 河村 直己*; 道村 真司*; 稲見 俊哉; 中村 俊幸*; 近藤 晃弘*; 金道 浩一*; et al.

Journal of the Physical Society of Japan, 82(12), p.124712_1 - 124712_5, 2013/12

 被引用回数:8 パーセンタイル:50.87(Physics, Multidisciplinary)

重い電子化合物であるYbRh$$_2$$Si$$_2$$のYb価数の温度磁場依存性をX線吸収分光で観測した。測定からは、何れも突然の変化なしに、Yb価数が2Kから200Kの範囲で温度の下降に伴い減少することと、0Tから33Tの範囲で磁場の増加に伴い増加することが明かになった。Ybの価数は、磁場と温度に依存して、2.92から2.96の範囲であった。価数が2Kでは0Tで2.92で33Tで2.93である点で、YbRh$$_2$$Si$$_2$$は価数揺動状態にあることがわかり、高磁場でも整数価数に届かない。これらの結果はYbの価数が整数価数の3+に非常に近く、降温に伴い減少し、磁場の印加に伴い3+に近づくというこれまでの知識を支持するものである。

論文

Study of exotic uranium compounds using $$^{238}$$U M$"o$ssbauer spectroscopy

筒井 智嗣; 中田 正美

M$"o$ssbauer Spectroscopy; Applications in Chemistry, Biology, and Nanotechnology, p.123 - 140, 2013/10

先端基礎研究センターで行われたウラン金属間化合物に関する$$^{238}$$Uメスバウア分光の結果に関してレビューを行った。われわれの研究以前には、$$^{238}$$U核の第1励起状態の核磁気モーメントの大きさが未知で、内部磁場を用いた磁性に関する定量分析は行うことができなかった。そこで、われわれは$$^{235}$$U NMRと$$^{238}$$Uメスバウア分光によるUO$$_{2}$$の内部磁場から$$^{238}$$U核の第1励起状態の核磁気モーメントを決定した。その後、種々のウラン金属間化合物、特に重い電子的振舞や2次元フェルミ面物質など、強相関電子系に分類される物質群についての$$^{238}$$Uメスバウア分光を行い、その物性の微 視電子状態について議論を行った。

97 件中 1件目~20件目を表示