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論文

Incommensurate antiferromagnetism in UTe$$_2$$ under pressure

Knafo, W.*; Thebault, T.*; Raymond, S.*; Manuel, P.*; Khalyavin, D. D.*; Orlandi, F.*; Ressouche, E.*; Beauvois, K.*; Lapertot, G.*; 金子 耕士; et al.

Physical Review X, 15(2), p.021075_1 - 021075_16, 2025/05

 被引用回数:0

The discovery of multiple superconducting phases in UTe$$_2$$ boosted research on correlated-electron physics. This heavy-fermion paramagnet was rapidly identified as a reference compound to study the interplay between magnetism and unconventional superconductivity with multiple degrees of freedom. The proximity to a ferromagnetic quantum phase transition was initially proposed as a driving force to triplet-pairing superconductivity. However, we find here that long-range incommensurate antiferromagnetic order is established under pressure. The propagation vector k$$_{rm m}$$ = (0.07, 0.33, 1) of the antiferromagnetic phase is close to a wavevector where antiferromagnetic fluctuations have previously been observed at ambient pressure. These elements support that UTe$$_2$$ is a nearly-antiferromagnet at ambient pressure. Our work appeals for theories modelling the evolution of the magnetic interactions and electronic properties, driving a correlated paramagnetic regime at ambient pressure to a long-range antiferromagnetic order under pressure. A deeper understanding of itinerant-f-electrons magnetism in UTe$$_2$$ will be a key for describing its unconventional superconducting phases.

論文

Surface and interfacial aggregation states in thin films of a polystyrene/polyrotaxane blend

田口 美岐*; 宮田 登*; 宮崎 司*; 青木 裕之; Ozawa, Satoru*; 長谷川 龍一 *; 盛満 裕真*; 川口 大輔*; 山本 悟*; 田中 敬二*

Polymer Journal, 7 Pages, 2025/03

 被引用回数:0 パーセンタイル:0.00(Polymer Science)

Polyrotaxane (PR) exhibits unique mechanical properties due to the ability of its cyclic molecules to move or slide along the axial chain. Thus, to design advanced polymer-based composite materials and organic devices, it is crucial to better understand the aggregation states at the surface and substrate interface in polymer films containing PR. Here, we report the depth profile of PR along the direction normal to the interface when it is mixed with polystyrene (PS). Neutron reflectivity and X-ray photoelectron spectroscopy revealed that PS and PR segregated at the surface and substrate interface, respectively, and that the extent of segregation depended on the length of PS. The surface enrichment of PS is driven by both energy and entropy, whereas the enrichment of PR at the substrate interface is energy driven.

論文

Water-intercalated and humidity-responsive lamellar materials by self-assembly of sodium acrylate random copolymers

堀池 優貴*; 青木 裕之; 大内 誠*; 寺島 崇矢*

Journal of the American Chemical Society, 147(8), p.6727 - 6738, 2025/02

 被引用回数:0 パーセンタイル:0.00(Chemistry, Multidisciplinary)

Herein, we report water-intercalated and humidity-responsive lamellar materials obtained from the self-assembly of sodium acrylate (ANa)/alkyl acrylate (RA) random copolymers. The random copolymers efficiently absorbed water into the hydrophilic ANa/main chain phase from the outer environment to form lamellar structures consisting of the water-intercalated hydrophilic segments and the hydrophobic side chains. The lamellar formation involves controlling the weight fraction of hydrophilic segments containing water to 40-70 wt% by the RA content, hydrophobic side chains, and the amount of absorbed water. The domain spacing can be controlled in the range of 2-6 nm. More interestingly, the lamellar materials reversibly afford expansion and contraction of the domain spacing in the sub-1 nm level via the absorption and release of water, in response to relative humidity. The multilayered lamellar formation process via the intercalation of water was analyzed in situ by neutron reflectometry and atomic force microscopy measurements under humid conditions. The polymer film further served as a moisture-sensitive actuator that macroscopically induces deformation responsive to humidity.

論文

Neutron reflectometry study on the interfacial layer of epoxy resin to improve adhesion strength

Liu, Y.*; 宮田 登*; 宮崎 司*; 春藤 淳臣*; 川口 大輔*; 田中 敬二*; 青木 裕之

ACS Applied Materials & Interfaces, 8 Pages, 2025/00

The performance of structural adhesives is strongly influenced by the interfacial structure between the adhesive and adherend. In this study, we developed a nanometric stable interfacial layer derived from an epoxy resin system containing excess hardener. This layer, formed on solid substrates, exhibited excellent structural stability, even after extensive solvent washing. Neutron reflectometry (NR) was employed to investigate its structure under both dry and humid conditions, revealing a robust and well-defined interface that suppressed moisture accumulation at the adherend interface. FT-IR spectroscopy confirmed an excess of unreacted amino groups in the adsorbed layer, enabling further curing reactions with freshly applied epoxy resin. Re-coating experiments demonstrated that the adsorbed layer remained intact after thermal curing, suggesting strong interfacial compatibility. Notably, the presence of the adsorbed layer led to a significant enhancement in adhesive performance. Lap shear tests showed that the adhesion strength of the epoxy resin nearly doubled when the adsorbed layer was introduced at the interface. This approach does not rely on external coupling agents or primers, but instead utilizes a homologous material system to tailor interfacial properties through molecular-level design. The strategy presented here offers a practical and scalable method for improving adhesion in epoxy systems. By directly engineering the adhesive interface using components intrinsic to the epoxy formulation, this method enables reliable and enhanced bonding performance without altering the bulk material.

論文

$$^{149}$$Sm synchrotron-radiation-based M$"{o}$ssbauer and $$mu^+$$SR studies of Sm$$_3$$Ru$$_4$$Ge$$_{13}$$

筒井 智嗣; 伊藤 孝; 中村 仁*; 吉田 実生*; 小林 義男*; 依田 芳卓*; 中村 惇平*; 幸田 章宏*; 東中 隆二*; 青木 大*; et al.

Interactions (Internet), 245(1), p.55_1 - 55_9, 2024/12

$$^{149}$$Sm SR-based M$"{o}$ssbauer and muon spin relaxation ($$mu^+$$SR) spectroscopies have been applied to Sm$$_3$$Ru$$_4$$Ge$$_{13}$$. The temperature dependence of the $$^{149}$$Sm SR-based M$"{o}$ssbauer spectra in the paramagnetic state implies the presence of dynamical nuclear Zeeman and/or quadrupole interactions. The time differential $$mu^+$$SR spectra also exhibit a marked temperature dependence in the paramagnetic state, indicating the presence of magnetic fluctuation in Sm$$_3$$Ru$$_4$$Ge$$_{13}$$ at least. These results in the present work infer that the dynamical hyperfine interactions observed using the mutually complementary spectroscopic methods are connected with the mechanism of the heavy fermion behavior in Sm$$_3$$Ru$$_4$$Ge$$_{13}$$.

論文

Measuring unit for synchronously collecting air dose rate and measurement position

川端 邦明; 今渕 貴志; 白崎 令人*; 鈴木 壮一郎; 伊藤 倫太郎; 青木 勇斗; 大森 崇純

ROBOMECH Journal (Internet), 11, p.11_1 - 11_11, 2024/09

This paper describes a measuring unit to realize the synchronous collection of air dose rate and measurement position for efficient dosimetry survey and data logging in a working space. The developed prototype comprises a three-dimensional light detection and ranging-based mapping part and a dosimetry part, which are integrated into a single measurement unit through an embedded computer that installs a ROS (Robot Operating System) framework. The unit can function as a standalone system with embedded batteries. Since it is portable, on-line data gathering in the workspace can be realized, thereby maintaining consistency between the air dose rate and the measurement position. In this paper, we describe the prototype system configuration and the experimental results obtained in the mockup test space and nuclear facility to discuss its performance.

論文

Influence of MC carbides on pitting corrosion resistance of weld metal in austenitic stainless steels

門井 浩太*; 冠野 裕大*; 青木 聡; 井上 裕滋*

ISIJ International, 64(9), p.1450 - 1456, 2024/07

 被引用回数:0 パーセンタイル:0.00(Metallurgy & Metallurgical Engineering)

オーステナイトステンレス鋼の溶接金属中の孔食に及ぼす化学組成の影響について検討した。クロムおよびモリブデンを多く含む試験片は、再活性化率が低いことが示された。チタンの添加は、耐孔食性を著しく低下させた。クロム欠乏領域はM$$_{23}$$C$$_{6}$$やTiCのような炭化物の近くに形成された。また、凝固時に生成したTiC相がM$$_{23}$$C$$_{6}$$析出の核となった。M$$_{23}$$C$$_{6}$$の析出により、クロムの拡散による空乏領域が発生し、耐孔食性の劣化を誘発した。

論文

In-plane movement of isolated poly(methacrylate) chains on a hydrophilic solid surface

Kawano, Masayuki*; 盛満 裕真*; Liu, Y.*; 宮田 登*; 宮崎 司*; 青木 裕之; 川口 大輔*; 山本 悟*; 田中 敬二*

Macromolecules, 57(14), p.6625 - 6633, 2024/07

 被引用回数:0 パーセンタイル:0.00(Polymer Science)

A better understanding of the dynamic behavior of polymer chains on solid surfaces is indispensable for the design and construction of high-performance polymer composites. We herein visualized the in-plane movement of isolated poly(methyl methacrylate) (PMMA) and poly(tert-butyl methacrylate) (PtBMA) single chains on hydrophilic silicon wafers under ambient conditions by atomic force microscopy. Isolated PMMA chains adsorbed to the substrate, whereas PtBMA chains diffused, the degree of which was dependent on the humidity. Neutron reflectivity revealed the formation of a layer of condensed water on the substrate. All-atomistic molecular dynamics simulations implied that the diffusivity difference of the two polymers was based on the submerged depth in which a part of a chain existed. That is, the interaction of a polymer with the surface of the hydrophilic substrate primarily governs its lateral movement, or adsorption behavior, facilitated by the presence of water.

論文

Universal access to water-compatible and nanostructured materials via the self-assembly of cationic alternating copolymers

筋田 涼太*; 青木 裕之; 竹中 幹人*; 大内 誠*; 寺島 崇矢*

ACS Macro Letters (Internet), 13(6), p.747 - 753, 2024/06

 被引用回数:2 パーセンタイル:28.80(Polymer Science)

Herein, we report the water-assisted self-assembly of alternating copolymers bearing imidazolium cations and hydrophobic groups to create water-compatible and nanostructured materials. The copolymers efficiently absorbed water into the cationic segments from the outer environments, depending on the relative humidity. The absorbed water serves as hydrophilic molecules to modulate the weight fraction of hydrophilic/hydrophobic units in the samples. Thus, the morphologies and domain spacing of the nanostructures can be controlled by not only the side chains, but also the amount of absorbed water. The self-assembly of the cationic copolymers, developed herein, afforded universal access to various morphologies, including lamella, gyroid, and cylinder, in addition to the precision control of the domain spacing at the 0.01 nm level.

論文

A Focusing supermirror for time-of-flight grazing-incidence small-angle neutron scattering measurement

山崎 大; 丸山 龍治; 青木 裕之; 花島 隆泰*; 阿久津 和宏*; 宮田 登*; 曽山 和彦

Quantum Beam Science (Internet), 9(2), p.20_1 - 20_12, 2024/06

This study developed a neutron-beam focusing supermirror for grazing-incidence small-angle neutron scattering (GISANS) measurements. It was fabricated by depositing NiC/Ti supermirror film with ion-beam sputtering on a precise elliptic surface of fused quartz figured using the elastic emission machining technique. Neutron measurements at a pulsed neutron reflectometer BL17 of MLF, J-PARC successfully demonstrated that the focusing supermirror enhances a beam intensity twentyfold compared with an optimally collimated beam, achieving the signal-to-background ratio of the focal spot as high as 500. The mirror can be readily installed and used at BL17.

論文

Hydrogenation of silicon-bearing hexagonal close-packed iron and its implications for density deficits in the inner core

森 悠一郎*; 鍵 裕之*; 青木 勝敏*; 高野 将大*; 柿澤 翔*; 佐野 亜沙美; 舟越 賢一*

Earth and Planetary Science Letters, 634, p.118673_1 - 118673_8, 2024/05

 被引用回数:1 パーセンタイル:41.61(Geochemistry & Geophysics)

水素による鉄の体積膨張に対するケイ素の効果を調べるため、高圧高温下でのhcp-Fe$$_{0.95}$$Si$$_{0.05}$$の中性子回折実験とX線回折実験を行った。中性子回折実験は重水素化hcp-Fe$$_{0.95}$$Si$$_{0.05}$$に対して13.5GPa, 900K及び12.1GPa, 300Kで行い、得られたプロファイルからリートベルト解析を用いて水素占有率を決定した。hcp-Fe-SiのP-V-T状態方程式を組み合わせることにより、hcp-Fe$$_{0.95}$$Si$$_{0.05}$$の水素による体積膨張が純粋なhcp鉄の体積膨張よりも10%大きいことを示した。得られた値を用いて、内核の密度欠損を再現できる水素量を見積もったところ、シリコンの影響がない場合に比べて50%減少した。hcp-Fe$$_{0.95}$$Si$$_{0.05}$$で内核の密度欠損を再現した場合、内核と外核で可能な水素量xはそれぞれ0.07と0.12-0.15と計算された。

論文

Field-induced insulator-metal transition in EuTe$$_2$$

竹内 徹也*; 本多 史憲*; 青木 大*; 芳賀 芳範; 木田 孝則*; 鳴海 康雄*; 萩原 政幸*; 金道 浩一*; 軽部 皓介*; 播磨 尚朝*; et al.

Journal of the Physical Society of Japan, 93(4), p.044708_1 - 044708_10, 2024/04

 被引用回数:0 パーセンタイル:0.00(Physics, Multidisciplinary)

Electrical and magnetic properties of divalent europium antiferromagnet EuTe$$_2$$ are studied on single crystals grown from Te-flux method. Antiferromagnetism occurs at 11 K with an insulating ground state. Application of magnetic field induces a sudden resistance drop leading to a phase transition to metallic state. Energy band calculations reveal the appearance of a Fermi surface pocket with Te-5p character induced by the polarized Eu moments.

論文

Reinforcement of superconductivity by quantum critical fluctuations of metamagnetism in UTe$$_2$$

常盤 欣文; Opletal, P.; 酒井 宏典; 神戸 振作; 山本 悦嗣; 木俣 基*; 淡路 智*; 佐々木 孝彦*; 青木 大*; 芳賀 芳範; et al.

Physical Review B, 109(14), p.L140502_1 - L140502_6, 2024/04

 被引用回数:6 パーセンタイル:84.81(Materials Science, Multidisciplinary)

超伝導体UTe$$_2$$の常伝導状態を$$b$$軸磁場に対するエントロピー解析によって調べた。メタ磁性揺らぎ(空間一様、$$Q=0$$)による磁場によるエントロピーの強い増加が観測された。この磁場依存性は遍歴メタ磁性の量子臨界性に関するHertz-Millis-Moriya理論によってよく記述される。特に、量子臨界領域の下界は超伝導転移温度$$T_c(B)$$の最小値の位置とよく一致する。この結果は、$$Q=0$$の揺らぎが超伝導を強めることを示唆している。

論文

Synthesis of heat-resistant living polymer particles by one-step reversible addition-fragmentation chain transfer precipitation polymerization of styrene and $$N$$-phenylmaleimide

山崎 駿*; 金子 直矢*; 加藤 敦也*; 渡邉 航平*; 青木 大輔*; 谷口 竜王*; 唐津 孝*; 上田 祐生; 元川 竜平; 大倉 滉生*; et al.

Polymer, 298, p.126846_1 - 126846_11, 2024/04

 被引用回数:5 パーセンタイル:74.19(Polymer Science)

Synthesis of heat-resistant, living polymer particles via one-step reversible addition-fragmentation chain transfer precipitation polymerization (RAFTPP) of styrene and $$N$$-phenylmaleimide is reported. Gel permeation chromatography and nuclear magnetic resonance spectroscopy confirmed that the polymerization proceeded in a living manner. The scanning electron microscopy results showed that the monodisperse P(St-PhMI) RAFTPP particles with a diameter of 1.88 micrometer were successfully synthesized. The P(St-PhMI) RAFTPP showed excellent thermal stability with a high glass transition temperature and a 5 percent weight loss temperature. The surface concentration of the RAFT groups was determined to be 0.181 groups/square-nanometer due to fragmentation of the RAFT groups exposed on the particles. The small-angle neutron scattering measurements showed the particle formation mechanism, in which the swollen, growing polymer chains were consumed for particle formation. The introduction of grafted chains by surface-initiated RAFT polymerization demonstrated the possibility of further functionalization of P(St-PhMI) RAFTPP particles by exploiting their living nature.

論文

Low reactivity of stoichiometric FeS with hydrogen at high-pressure and high-temperature conditions

高野 将大*; 鍵 裕之*; 森 悠一郎*; 青木 勝敏*; 柿澤 翔*; 佐野 亜沙美; 飯塚 理子*; 土屋 卓*

Journal of Mineralogical and Petrological Sciences (Internet), 119(1), p.240122_1 - 240122_9, 2024/00

 被引用回数:0 パーセンタイル:0.00(Mineralogy)

硫化鉄(FeS)の高圧高温下での水素化は、水素と硫黄が地球や他の地球型惑星のコアの軽元素として有望な候補であることから注目されている。これまでのFeSの水素化反応に関する報告では、出発物質の化学組成は十分に明らかにされていなかった。本研究では、Fe1.000S(トロイライト)を出発物質としたFe-S-H系の高温高圧条件下での中性子回折とX線回折のその場測定を報告する。決定された占有率は、以前の研究で報告されたものより著しく低く、FeSの水素化は硫化鉄の化学組成に強く影響されることを示している。

論文

Development of a D$$_2$$O/H$$_2$$O vapor generator for contrast-variation neutron scattering

有馬 寛*; 高田 慎一; 笠井 聡*; 大内 啓一*; 森川 利明*; 宮田 登*; 宮崎 司*; 青木 裕之; 岩瀬 裕希*; 廣井 孝介; et al.

Journal of Applied Crystallography, 56(6), p.1802 - 1812, 2023/12

 被引用回数:6 パーセンタイル:81.06(Chemistry, Multidisciplinary)

The contrast-variation technique in neutron scattering experiments plays a pivotal role in distinguishing partial structures within multi-component complexes, facilitating the elucidation of distinct sample constituents. This differentiation is achieved using different isotopes, namely hydrogen and deuterium, which possess varying neutron scattering characteristics. This study presents a novel vapor generator designed for neutron scattering experiments, enabling continuous control of the D$$_2$$O/H$$_2$$O ratio of the vapor. This feature is especially useful for contrast-variation studies. The generator features two saturators and four mass flow controllers, allowing for the rapid and independent generation of D$$_2$$O/H$$_2$$O vapors. Additionally, the incorporation of the two-temperature method ensures accurate dew point control within a margin of $$pm$$0.2$$^{circ}$$Cdp. This setup proves useful for conducting time-resolved experiments and can accelerate research on functional polymers, such as polymer electrolyte membranes for fuel cells, where water potential assumes critical importance.

論文

Microphase separation of cationic homopolymers bearing alkyl ammonium salts into sub-4 nm lamellar materials with water intercalation channels

筋田 涼太*; 今井 彩帆里*; 大内 誠*; 青木 裕之; 寺島 崇矢*

Macromolecules, 56(23), p.9738 - 9749, 2023/12

 被引用回数:5 パーセンタイル:37.67(Polymer Science)

Constructing ordered ionic nanostructures into bulk polymers and thin films is an important technique to create functional materials, such as polyelectrolytes and proton- and ion-conducting materials, for various applications. Herein, we report microphase separation of cationic homopolymers bearing alkyl ammonium bromides to create sub-4 nm lamellar materials, where an ionic phase is alternatingly layered with a hydrophobic alkyl phase and serves as a channel for water intercalation. We prepared cationic homopolymers with linear or branched alkyl pendants (octyl or 2-ethylhexyl group: C8-eicosyl or 2-octyldodecyl group: C20) via the free radical polymerization of 2-(dimethylamino)ethyl acrylate (DMAEA), followed by the quaternization of the polyDMAEA with corresponding alkyl bromides. The homopolymers carrying linear hexadecyl, octadecyl, and eicosyl groups were crystalline at room temperature, whereas the others were amorphous. The homopolymers bearing linear alkyl pendants longer than the decyl group or branched alkyl pendants larger than the 2-butyloctyl group formed lamellar structures by the self-assembly of the side chains. The domain spacing can be controlled between 2.5 and 3.7 nm by tuning the pendant structures and are smaller than that formed by the corresponding random copolymers. A cationic homopolymer bearing crystalline octadecyl groups maintained lamellar structures up to $$sim$$210 $$^circ$$C far beyond the melting temperature ($$sim$$50 $$^circ$$C). The cationic homopolymer further formed a multilayered lamellar thin film on a silicon substrate, in which the cationic layers absorbed water under humid conditions and reversibly released the water therefrom in a N$$_2$$ gas atmosphere.

論文

Longitudinal spin fluctuations driving field-reinforced superconductivity in UTe$$_2$$

徳永 陽; 酒井 宏典; 神戸 振作; Opletal, P.; 常盤 欣文; 芳賀 芳範; 北川 俊作*; 石田 憲二*; 青木 大*; Knebel, G.*; et al.

Physical Review Letters, 131(22), p.226503_1 - 226503_7, 2023/12

 被引用回数:14 パーセンタイル:85.96(Physics, Multidisciplinary)

Our measurements of $$^{125}$$Te NMR relaxations reveal an enhancement of electronic spin fluctuations above $$mu_0H^*sim15$$~T, leading to their divergence in the vicinity of the metamagnetic transition at $$mu_0H_mapprox35$$~T, below which field-reinforced superconductivity appears when a magnetic field ($$H$$) is applied along the crystallographic $$b$$ axis. The NMR data evidence that these fluctuations are dominantly longitudinal, providing a key to understanding the peculiar superconducting phase diagram in $$H|b$$, where such fluctuations enhance the pairing interactions.

論文

Impact of the Ce$$4f$$ states in the electronic structure of the intermediate-valence superconductor CeIr$$_3$$

藤森 伸一; 川崎 郁斗; 竹田 幸治; 山上 浩志; 雀部 矩正*; 佐藤 芳樹*; 清水 悠晴*; 仲村 愛*; Maruya, A.*; 本間 佳哉*; et al.

Electronic Structure (Internet), 5(4), p.045009_1 - 045009_7, 2023/11

The electronic structure of the $$f$$-based superconductor $$mathrm{CeIr_3}$$ was studied by photoelectron spectroscopy. The energy distribution of the $$mathrm{Ce}~4f$$ state was revealed by the $$mathrm{Ce}~3d-4f$$ resonant photoelectron spectroscopy. The $$mathrm{Ce}~4f$$ state was mostly distributed in the vicinity of the Fermi energy, suggesting the itinerant character of the $$mathrm{Ce}~4f$$ state. The contribution of the $$mathrm{Ce}~4f$$ state to the density of states (DOS) at the Fermi energy was estimated to be nearly half of that of the$$mathrm{Ir}~5d$$ states, implying that the $$mathrm{Ce}~4f$$ state has aconsiderable contribution to the DOS at the Fermi energy. The $$mathrm{Ce}~3d$$ core-level and $$mathrm{Ce}~3d$$ X-ray absorption spectra were analyzed based on a single-impurity Anderson model. The number of the $$mathrm{Ce}~4f$$ state in the ground state was estimated to be 0.8-0.9, which is much larger than the values obtained in the previous studies (i.e., 0-0.4).

論文

Magnetic and fermi surface properties of semimetals EuAs$$_3$$ and Eu(As$$_{1-x}$$P$$_x$$)$$_3$$

大貫 惇睦*; 軽部 皓介*; 青木 大*; 仲村 愛*; 本間 佳哉*; 松田 達磨*; 芳賀 芳範; 竹内 徹也*

Journal of the Physical Society of Japan, 92(11), p.114703_1 - 114703_12, 2023/11

 被引用回数:1 パーセンタイル:22.15(Physics, Multidisciplinary)

Single crystal samples of a series of semimetallic magnet Eu(As$$_{1-x}$$P$$_x$$)$$_3$$ have successfully grown. By measuring magnetization, Hall resistivity and de Haas-van Alphen oscillations, large anomalous Hall resistivity arising from peculiar magnetic phase diagram was identified.

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