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As studied by X-ray magnetic circular dichroismWan, Y.*; 芝田 悟朗; 竹田 幸治*; 岡根 哲夫; 斎藤 祐児; 山上 浩志; 藤森 淳*; 他10名*
Physical Review Materials (Internet), 10(5), p.054402_1 - 054402_8, 2026/05
被引用回数：1 パーセンタイル：0.00(Materials Science, Multidisciplinary)In order to unveil the nature of the ferromagnetism in (Ba,K)(Zn,Mn)As, its magnetization process has been studied by X-ray magnetic circular dichroism (XMCD) at the Mn 
edge in a wide range of temperature and magnetic field. The average magnetization of the Mn atoms as a function of magnetic field (
-
curves) at various temperatures could be successfully explained by a mixture of paramagnetic (PM), superparamagnetic (SPM), and ferromagnetic (FM) components as previously reported for GaMnAs, revealing the complex nature of the ferromagnetism in (Ba,K)(Zn,Mn)As. The average magnetization of the SPM clusters of different sizes and the FM regions were found to be small compared to those in GaMnAs, which we attribute to the antiferromagnetic interaction between nearest-neighbor Mn atoms in (Ba,K)(Zn,Mn)As on the basis of recent theoretical predictions.
CaOsO
assessed by X-ray magnetic dichroism measurements芝田 悟朗; 藤森 淳; 他10名*
Physical Review B, 113(16), p.165151_1 - 165151_7, 2026/04
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)We studied the cubic double perovskite Ba
CaOsO
containing the Os
(
) ions, which exhibits a phase transition to a `hidden order' below 
K, by X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) at the Os edge. The cubic ligand-field splitting between the 
and 
levels of Os 
was deduced by XAS to be 
eV. The temperature dependence of the XMCD spectra was consistent with a 
meV residual cubic splitting of the lowest 
multiplet state into the non-Kramers 
doublet ground state and the 
triplet excited state. Ligand-field (LF) multiplet calculation under fictitious strong magnetic fields indicated that the exchange interaction between nearest-neighbor octupoles should be as strong as 
meV if a ferro-octupole order is stabilized in the `hidden-ordered' state, consistent with the exchange interaction of 
meV previously predicted theoretically using model and density functional theory calculations.
Cao, T.*; Wei, D.*; Gong, W.; 川崎 卓郎; Harjo, S.; 他10名*
Materials Science & Engineering A, 940, p.148534_1 - 148534_16, 2025/09
被引用回数：3 パーセンタイル：64.95(Nanoscience & Nanotechnology)The thermal stability of microstructure and mechanical performance is crucial for the industrial application of laser powder bed fusion (LPBF) superalloy components in gas turbines and jet engines. This work investigated the microstructural evolution and strengthening mechanism of LPBF Mar-M509 cobalt-based superalloy before and after thermal exposure at 1200 
C using multi-scale microstructural characterization and in situ neutron diffraction tensile testing. The as-built Mar-M509 superalloy exhibited a heterogeneous microstructural features with coarse columnar and fine equiaxed grains, both containing dendritic and cellular substructures enriched with nanoscale carbides and high-density dislocations. The ultra high strength of the as-built sample was primarily attributed to dislocation-precipitation synergistic strengthening. After thermal exposure at 1200 C for 4 h, the dendritic and cellular substructures disappeared and the dislocation density decreased significantly. This study reveals the microstructural evolution and instability of LPBF Mar-M509 superalloy under high-temperature exposure and the impacts on mechanical properties, which provides critical support for the development of cobalt-based superalloys in high-temperature application fields.
関 祐一*; 藤森 伸一; 他10名*
Physical Review Letters, 135(4), p.046402_1 - 046402_7, 2025/07
被引用回数：1 パーセンタイル：41.22(Physics, Multidisciplinary)In transition-metal compounds, the transition-metal d electrons play an important role in their physical properties; however, the effects of the electron correlation between the ligand p electrons have not been clear yet. In this Letter, the Ru 4d and O 2p partial density of states (PDOS) in transition-metal oxide SrRuO involving Weyl fermions are investigated by resonant photoemission spectroscopy. The observations demonstrate that the O 2p PDOS is distorted from that predicted by first-principles calculations than the Ru 4d PDOS. The results indicate that the electron correlation in the ligand orbitals will be important to understand the electronic structure of the p-d hybridized state in strongly correlated electron systems, even with topological states.
田中 裕久*; 松村 大樹; 他10名*
International Journal of Hydrogen Energy, 141, p.1088 - 1097, 2025/06
被引用回数：1 パーセンタイル：23.08(Chemistry, Physical)Global efforts are being made to decarbonize the energy sector. Liquefied (cryogenic) hydrogen is suitable for large-scale storage and transportation due to its high storage density, so it is likely to play a fundamental role in the future hydrogen economy. The STACY project, "Towards the Safe Storage and Transport of Cryogenic Hydrogen", is investigating safety aspects of liquid hydrogen in order to overcome potential safety risks. Research is being conducted into passive autocatalytic recombiners using cutting-edge catalyst technology to enable them to be used in conditions where liquid hydrogen escapes, evaporates and forms a cold (
50C) explosive gas mixture with the ambient air. To this end, the crystal structure of the catalyst was designed at the atomic level, an actual catalyst was prototyped, and repeated tests were carried out on a laboratory scale and in a large reaction vessel. Progress has been made in developing catalysts that can oxidize hydrogen even at very low temperatures, high expansion, and low-oxygen environments, are resistant to catalyst poisons, and can prevent spontaneous unintended ignition. The tested catalyst technologies use different carrier materials (alumina and ceria) to control the surface state of precious metals and suppress hydrogen ignition through a multilevel configuration.
濱田 翔太*; 松村 大樹; 他10名*
SAE Technical Paper 2025-01-8476 (Internet), 6 Pages, 2025/04
In order to comply with the tightening of global regulations on automobile exhaust gas, further improvements to exhaust gas control catalysts and upgrades to on-board diagnostics (OBD) systems must be made. Currently, oxygen storage capacity (OSC) is monitored by front and rear sensors before and after the catalyst, and deterioration is judged by a decrease in OSC, but it is possible that catalyst deterioration may cause the rear sensor to detect gas that has not been sufficiently purified. It is important to observe the activity changes when the catalyst deteriorates in more detail and to gain a deeper understanding of the catalyst mechanism in order to create guidelines for future catalyst development. In this study, we used a 
-TG (micro thermogravimetric balance) to analyze in detail how differences in design parameters such as the type of precious metal, detection temperature, and mileage (degree of deterioration) affect the OSC rate in addition to the OSC of the ceria-based composite oxide of the entire catalyst. It was found that CZY has better durability in terms of both OSC rate and amount than CZ. Furthermore, by comparing the results of experiments using time-resolved dispersive X-ray absorption fine structure (DXAFS) using synchrotron radiation, the reduction behavior of ceria was analyzed in more detail.
堀 順一*; 佐野 忠史*; 高宮 幸一*; 福谷 哲*; 中村 詔司; 名内 泰志*; 他3名*; 他10名*
KURNS-EKR-21, p.10 - 14, 2025/01
本プロジェクト研究「原子炉施設廃止措置に関する基礎的研究」は、原子炉施設の廃止措置を安全且つ効率的に実施するために必要な基盤データの整備及び測定技術の開発を行うことによって、今後の京大研究炉の廃止措置作業に活用すると共に、福島第一原子力発電所で生じた燃料デブリの管理を含めた廃止措置全般の技術開発に資することを目的して、令和4年度から3か年にわたり実施された。本研究プロジェクトは、目的達成のために、7研究課題から構成されており、京都大学および他機関がそれぞれ分担して実施してきた。原子力機構は、「廃止措置における放射性廃棄物核種の核的特性に関する研究」を分担し、廃止措置で問題になる核種の生成量を評価するのに資する中性子断面積データの取得を目的として、数核種を選定してそれらの中性子捕獲断面積の導出に成功した。
小杉 美央子*; 吉川 貴史; 齊藤 英治; 他10名*
ACS Applied Materials & Interfaces, 16(46), p.64190 - 64196, 2024/11
被引用回数：4 パーセンタイル：34.77(Nanoscience & Nanotechnology)Atom-vacancy-defects present in various materials yield numerous interesting physical phenomena, even obstructing high performance in some cases. On the other hand, their valuable applications to novel devices, such as nitrogen vacancy centers in diamond for quantum bits, have gathered significant attention. In particular, these tendencies become more substantial in two-dimensional (2D) (atomically) thin van der Waals layers. However, correlations with various kinds of atom defects are still under exploration. Herein, we find the stochastic behaviors of large hysteresis loops with strong photoresponse in the static electrical properties in few-atom layer semiconductors, molybdenum disulfide (MoS). The temperature dependence and transmission electron microscopy reveal that they arise from pairs of two neighboring in-plane S-vacancy defects, which predominantly present only around the interface at the MoS flake/substrate, with activation energies similar to 0.35 eV. The low-frequency (
) (LF) noise measurements clarify a high f shift in the two 1/ 2-dependent regimes, implying stochastic behaviors of electric charges through the S-vacancy pairs with high-speed charge(spin) transitions across low kinetic energy barriers between narrow discrete states. The shallow energy sates are formed from the highly uniform S-vacancy pairs interacting with Mo atoms, which act like quantum dots. The observed stochastic operation holds promise for various application, particularly for probabilistic neuromorphic computation in artificial intelligence.
Kiliyankil, V. A.*; 福谷 克之; 他10名*
Journal of Materials Chemistry A, 12(42), p.28731 - 28743, 2024/10
被引用回数：5 パーセンタイル：34.77(Chemistry, Physical)The hydrogen evolution reaction (HER) on platinum (Pt) electrocatalysts involves the generation of hydrogen atoms and the formation of hydrogen molecules. It is commonly believed that the sites on the surfaces of the terrace (111, 110, and 100) domains are responsible for the formation of hydrogen molecules. However, the electrochemistry of the hydrogen atom generation is not well understood. We created edge-rich platinum electrocatalysts using nano-fabrics comprising entire single-walled carbon nanotubes (SWCNTs) as templates and supports. We then conducted the HER on the edge-rich Pt/SWCNT hybridized electrocatalysts and gained new insights into the electrochemical properties and functions of the edge sites. We propose that the edge sites are oxidized and serve two important functions: they act as atomic barriers, allowing electrons to accumulate within the terrace (111, 110, and 100) domains, and they transfer the electrons to the hydronium ions in the electrical double layer through discharge. Enhancing the discharge capability of the electrocatalysts is an efficient way to reduce the amount of platinum required, and this can be applied to various precious metal-based electrocatalysts to enhance their electrocatalytic activities and durability.
Mo, 
Mo, and 
MoKumar, V.*; Chapman, R.*; Ollier, J.*; Orlandi, R.; Smith, J. F.*; Spohr, K.-M.*; Torres, D. A.*; Wady, P.*; 他10名*
Physical Review C, 110(4), p.044308_1 - 044308_18, 2024/10
被引用回数：4 パーセンタイル：66.07(Physics, Nuclear)Excited states of the molybdenum isotopes 
Mo were populated in two experiments which used fusion-fission and binary grazing reactions. In the first experiment, the GASP array of Ge detectors was used to detect 
rays from fusion-fission products from the 
S + 
Yb reaction at 230 MeV. In the multinucleon transfer experiment, a 530-MeV beam of 
Zr ions was incident on a thin 
Sn target; projectile-like ejectiles were detected and identified using the PRISMA magnetic spectrometer and their associated rays detected using the CLARA array of Clover detectors. Previously known bands were extended in all isotopes, and a new g
band was established in Mo. The observed level schemes were compared with shell-model calculations, which reproduce the general features of the energy spectrum of excited states of Mo, Mo, and Mo, although not in detail. For the h
negative-parity decay sequences of the three isotopes studied, evidence is presented for nuclear shape changes with increasing neutron number.
= 82 shell closureZhang, W. Q.*; Andreyev, A. N.; 他10名*
Physical Review C, 110(4), p.044301_1 - 044301_7, 2024/10
被引用回数：0 パーセンタイル：0.00(Physics, Nuclear)Based on the 
values deduced from the linear extrapolations along isotopic chains and on the universal decay law, the proton- and 
-decay partial half-lives are calculated for odd-, even-
neutron-deficient Bi-Pa isotopes. Eight proton-emission states in five new isotopes are suggested. The calculated half-lives for the 1/2
states in 
Bi and 
At are around 100 ns, too short to be studied using the recoil separator setups, which strongly encourages the development of new experimental techniques and devices to search for new submicrosecond proton-emitting nuclei.
U and 
ThFilipescu, D.*; Gheorghe, I.*; Goriely, S.*; 西尾 勝久; 宇都宮 弘章*; 洲嵜 ふみ; 廣瀬 健太郎; 他10名*
Physical Review C, 109(4), p.044602_1 - 044602_23, 2024/04
被引用回数：5 パーセンタイル：73.54(Physics, Nuclear)New measurements of photofission and photoneutron reactions on U and Th in the Giant Dipole Resonance (GDR) energy region have been performed at the laser Compton-scattering -ray source of the NewSUBARU synchrotron radiation facility. The photoneutron (
) with 
= 1-3 and photofission (
) reactions have been discriminated by considering a Gaussian distribution of prompt-fission-neutron (PFN) multiplicities predicted by the theory of evaporation in sequential neutron emission from excited fission fragments. We report experimental (
), (
), (
) and () cross sections, average energies of PFNs and of(, 
) photoneutrons, as well as the mean number of PFNs per fission and the width of the PFNs multiplicity distribution. Based on these primary experimental results and combined with reasonable assumptions, we extract also the first- and second-chance fission contributions.
Ahn, J. K.*; 長谷川 勝一; 今井 憲一*; 佐甲 博之; 佐藤 進; 谷田 聖; 他10名*
Nuclear Instruments and Methods in Physics Research A, 1047, p.167775_1 - 167775_13, 2023/02
被引用回数：2 パーセンタイル：25.06(Instruments & Instrumentation)We have constructed a conduction-cooled superconducting dipole magnet for the Hyperon spectrometer at Japan Proton Accelerator Research Complex (J-PARC). The magnet is a Helmholtz-type dipole magnet with two circular coils with a radius of 500 mm separated by 500 mm. It provides a uniform magnetic field of 1.0 T or higher in a volume of 
mm 
600 mm, covering the drift region of a time projection chamber (TPC). Owing to the target location inside the TPC, the Hyperon spectrometer has a broad angular coverage with a nearly 
solid angle. We have successfully excited the magnet up to 1.3 T. At 1.0 T, we operated it stably for more than 1 week in single-magnet configuration and double-magnet configuration with a normal-conducting 0.7-T dipole magnet located 30 cm apart. The measured magnetic field distribution in the TPC volume is consistent with the calculated field map.
nuclear modification at backward and forward rapidity in 
, Al, and Au collisions at 
GeVAcharya, U. A.*; 長谷川 勝一; 今井 憲一*; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他310名*
Physical Review C, 105(6), p.064912_1 - 064912_15, 2022/06
被引用回数：22 パーセンタイル：91.53(Physics, Nuclear)Suppression of the 
nuclear-modification factor has been seen as a trademark signature of final-state effects in large collision systems for decades. In small systems, the nuclear modification was attributed to cold-nuclear-matter effects until the observation of strong differential suppression of the state in 
collisions suggested the presence of final-state effects. Results of and measurements in the dimuon decay channel are presented here for , Al, and Au collision systems at GeV. The results are predominantly shown in the form of the nuclear-modification factor, 
, the ratio of the invariant yield per nucleon-nucleon collision in collisions of proton on target nucleus to that in collisions. Measurements of the and nuclear-modification factor are compared with shadowing and transport-model predictions, as well as to complementary measurements at Large-Hadron-Collider energies.
Mg
Ni
Mn
O (0 
x 0.07) from electrochemical and muon spin relaxation studiesMa, L. A.*; 杉山 純; 他10名*
Physical Chemistry Chemical Physics, 23(42), p.24478 - 24486, 2021/11
被引用回数：12 パーセンタイル：56.22(Chemistry, Physical)Sodium transition metal oxides with a layered structure are one of the most widely studied cathode materials for Na ion batteries. Since the mobility of Na in such cathode materials is a key factor that governs the performance of material, electrochemical and muon spin rotation and relaxation techniques are here used to reveal the Na ion mobility in a P2-type P2-type NaMgNiMnO (x = 0, 0.02, 0.05 and 0.07) cathode material. Combining electrochemical techniques such as galvanostatic cycling, cyclic voltammetry with SR, we have successfully extracted both self-diffusion and chemical-diffusion under a potential gradient, which are essential to understand the electrode material from an atomic-scale viewpoint. The results indicate that a small amount of Mg substitution has strong effects on the cycling performance and the Na mobility.
clarified with high-pressure 
SR杉山 純; 他10名*
Physical Review B, 101(17), p.174403_1 - 174403_10, 2020/05
被引用回数：11 パーセンタイル：44.14(Materials Science, Multidisciplinary)ミュオンスピン緩和法により、擬一次元スピン系BaVSの粉末試料における磁気的性質を研究した。常圧では
=31K以下で不整合反強磁性秩序状態を示す。は、圧力が増加してもほぼ一定であるが、1.4GPa以上において急激に減少する。最終的には1.8GPaで消滅し、それ以上では金属相が安定化する。このは1.4GPa以上で生じる圧力誘起金属絶縁体転移温度に相当する。
Oset, E.*; 他10名*; 岡 眞
Acta Physica Polonica B, 47(2), p.357 - 365, 2016/02
被引用回数：3 パーセンタイル：24.55(Physics, Multidisciplinary)メソン複数個を含むエキゾチックハドロンに関する研究成果をレビューした。未発見の状態については、今後の実験による探索を示唆した。
Thalmeier, R.*; 谷田 聖; 他102名*
Journal of Instrumentation (Internet), 11(1), p.C01044_1 - C01044_10, 2016/01
被引用回数：2 パーセンタイル：9.56(Instruments & Instrumentation)The upgrade of the Belle II experiment plans to use a vertex detector based on two different technologies, DEPFET pixel (PXD) technology and double side silicon microstrip (SVD) technology. The vertex electronics are characterized by the topology of SVD bias that forces to design a sophisticated grounding because of the floating power scheme. The complex topology of the PXD power cable bundle may introduce some noise inside the vertex area. This paper presents a general overview of the EMC issues present in the vertex system, based on EMC tests on an SVD prototype and a study of noise propagation in the PXD cable bundle based on Multi-conductor transmission line theory.
都留 智仁; Lobzenko, I.; 椎原 良典*; Wei, D.*; 山下 真一郎; 板倉 充洋; 他10名*
no journal, ,
ハイエントロピー合金(HEA)は、5元素またはそれ以上の成分が高濃度で混合した結晶構造を持つ合金として定義される。FCC構造とBCC構造でそれぞれCoCrFeNiMn(Cantor)合金とZrNbTaTiHf(Senkov)合金という強度と延性を両立した合金系が発見されており、これらの組成を軸にさらに優れた合金系の開発が行われている。力学特性の向上に対する機構は、格子の局所ひずみに対応する平均二乗原子変位(MSAD)による効果に加えて、FCC構造では双晶形成、BCC構造では特異な転位運動が重要な役割を果たしている。本研究では、FCC構造とBCC構造を有するHEAを対象に、第一原理計算に基づくシミュレーションを用いて欠陥構造の諸特性について検討する。MoNbTaVWとZrNbTaTiHfの2つのBCC-HEAにおけるRandom構造と800KのMC計算から得られた短距離秩序を有する構造に対して、135のサイトに転位双極子が導入された際のエネルギーの分布を評価した。その結果、2つの合金ではMSADが大きく異なっており、格子のひずみが大きなZrNbTaTiHfでは転位の形成エネルギーが小さくなることがわかった。
越智 康太郎; 森下 祐樹; 中間 茂雄; 眞田 幸尚; 他10名*
no journal, ,
To evaluate the emergency radiation monitoring capabilities of various countries, a coordinated field exercise involving Japan, France, the Republic of Korea, and Canada was conducted near the Fukushima Daiichi Nuclear Power Sation. Under standardized conditions, manborne, carborne, and airborne surveys were performed using different detector systems to assess ambient dose equivalent rates (air dose rates). JAEA employed CsI(Tl) detectors for manborne and carborne surveys, and LaBr
(Ce) scintillation detectors for airborne surveys using an unmanned helicopter. Despite differences in equipment and analysis methods, all teams observed consistent trends in air dose rate distributions. These results demonstrate the feasibility of producing internationally comparable dose rate maps and emphasize key factors such as shielding and energy response in dose rate assessments.
