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Wu, C.*; Qiu, X.*; 田中 万也; 谷 幸則*; Lloyd, J. R.*; Yu, Q.*
Bioresource Technology, 456, p.134916_1 - 134916_9, 2026/09
被引用回数：0マンガン酸化菌は環境中においてMn(II)を酸化することでMn(IV)酸化物を形成する。こうしたバイオミネラリゼーションにより形成するMn(IV)酸化物は環境中の放射性核種の挙動に影響を与える。近年、環境中での人為的なナノプラスチック(NP)の汚染が進んでおり、本研究ではNPがバイオミネラリゼーションに与える影響を調べた。その結果、低濃度NPは形成するMn(IV)酸化物の結晶性に影響を与え、高濃度NPではMn(II)酸化が阻害されることが分かった。こうしたNPによるバイオミネラリゼーションへの影響は、環境中での金属元素や放射性核種の挙動に影響を与える可能性がある。
alteration phases under chemically complex conditionsMei, H.*; 青柳 登; 高木 聖也; 斉藤 拓巳*
Journal of Hazardous Materials, 514, p.142804_1 - 142804_11, 2026/08
The study examines how uranium dioxide, a key component of spent nuclear fuel and Fukushima fuel debris, alters under oxidizing conditions relevant to storage and accident environments. Factors such as boric acid, hydrogen peroxide, seawater, and cement leachates were included to simulate realistic chemical conditions. After five months, the alteration products were analyzed using X ray diffraction and cryogenic time resolved laser fluorescence spectroscopy. X-ray diffraction detected only small amounts of metaschoepite in simple systems and failed to identify products in more complex environments. In contrast, cryogenic fluorescence spectroscopy successfully identified uranium six phases in all samples and revealed detailed chemical forms that X ray methods could not detect. Two distinct fluorescent components of uranium were identified, both linked to metaschoepite. The results highlight the importance of advanced spectroscopy methods for detecting subtle uranium phases that control early reactivity and release. These findings improve understanding of uranium behavior in nuclear waste systems and contribute to safer management strategies for Fukushima debris and long term storage of spent nuclear fuel.
南 晶子*; 松野 治貴*; 森田 恭平*; 松木 麟太朗*; 小手川 恒*; 播磨 尚朝*; 芳賀 芳範; 山本 悦嗣; 大貫 惇睦*; 藤 秀樹*
Journal of the Physical Society of Japan, 95(7), p.074711_1 - 074711_11, 2026/07
We performed 
Be-NMR measurements on UBe to probe its superconducting state. The Knight shift behavior indicates spin-triplet pairing with anisotropic spin susceptibility reduction below 
, providing strong evidence for a triplet state. The 
data support a multiband, fully gapped model, and symmetry analysis suggests an 
order parameter, consistent with a fully gapped spin-triplet topological superconductor.
紅林 秀和*; 山本 慧; 関 剛斎*; 他9名*
Nature Materials, 25(7), p.1167 - 1174, 2026/07
被引用回数：0 パーセンタイル：0.00(Chemistry, Physical)Spin transfer torques (STTs) control magnetisation by electric currents, enabling a range of nano-scale spintronic applications. They can destabilise the equilibrium magnetisation state by counteracting magnetic relaxation. Here, we maximise the STT effect through a dedicated growth-annealing protocol for CoFeB thin films, such that magnetic anisotropies originating from the interface and shape almost cancel each other. The nearly isotropic magnets enable low-current dynamical stabilisation of the magnetisation in the direction opposite to an applied magnetic field, thereby realising a spintronic analogue of the Kapitza pendulum. In an intermediate current regime, the STT drives large magnetisation vector fluctuations that cover the entire Bloch sphere. The continuous variable associated with the stochastic magnetisation direction may serve as a resource for probabilistic computing and neuromorphic hardware. Our results establish isotropic magnets as a platform to study as-yet-uncharted, far-from-equilibrium spin dynamics including anti-magnonics, with promising implications for unconventional computing paradigms.
神田 聡太郎*; 池戸 豊*; 大石 裕*; 下村 浩一郎*; 髭本 亘; 伊藤 孝; 中沢 雄河*; 林 幹稀*; 足立 匡*
JPS Conference Proceedings (Internet), 45, p.011044_1 - 011044_9, 2026/06
Muons serve as a highly sensitive local magnetic probe in materials science. While traditional 
SR relies on 4 MeV surface muons, investigations of thin films and interfacial phenomena demand precisely controlled low-energy muon beams. At J-PARC MLF MUSE, the U1 beamline delivers ultra-slow muons (USM) via laser ionization of thermal muonium. In the U1A experimental area, a muon spin spectrometer has been installed for USM-SR measurements. The spectrometer is mounted on a high-voltage platform for implantation energy control from nearly zero to 30 keV. Comprehensive beam characterization has demonstrated a spatial beam profile of 4 mm FWHM and a temporal width of 2 ns at the spectrometer's sample position. Commissioning of the spectrometer has demonstrated stable beam alignment and high time resolution in positron detection. In this work, we report these commissioning results and discuss potential upgrades for expanding the instrument's capabilities for future user programs.
Cd
廣瀬 雄介; 土塔 寛*; 竹内 徹也*; 三宅 厚志*; 徳永 将史*; 仲村 愛*; 本間 佳哉*; 青木 大*; 本多 史憲*; 摂待 力生*
Journal of Physics; Condensed Matter, 38(24), p.245601_1 - 245601_11, 2026/06
被引用回数：0The electronic state of UPdCd, which exhibits a magnetic transition at 
5 K, is investigated by means of transport, high-field magnetization up to 55 T, specific heat in magnetic fields, and de Haas-van Alphen (dHvA) measurements, and compared with the non-5f compound ThPdCd. A metamagnetic transition is observed at 
15-20 T, which continuously connects to in the H-T phase diagram. Although the magnetization reaches large values at high fields, the ordered magnetic moment is estimated to be small from small anomalies in specific heat at and in magnetization at 
. The observed dHvA frequencies reveal enhanced cyclotron effective masses of 30 
, which are much heavier than those in ThPdCd. These experimental results indicate that 5f-derived bands contribute to the large electronic specific heat coefficient of 670 mJ/mol K
, demonstrating the dual localized-itinerant character of 5f electrons in UPdCd.
-decay of 
TeCox, I.*; Grzywacz, R.*; King, T. T.*; Rykaczewski, K. P.*; 西尾 勝久; 他30名*
Nature, 654(8117), p.52 - 56, 2026/06
被引用回数：0 パーセンタイル：0.00(Multidisciplinary Sciences)The radioactivity of the particle is among the most compelling evidence for the existence of cluster structures in atomic nuclei. During the decay process, a preexisting particle tunnels through the potential barrier formed by the residual nucleus. The degree of preformation of the particle, a strongly bound system of two protons and two neutrons, is extracted from the data by dividing the -decay probability by the barrier penetrability for a given particle energy. The preformation probability changes rapidly near nuclear shell closures, which is direct evidence that clustering is connected to nuclear structure. Enhanced preformation was observed in the lightest -particle emitters, spherical tellurium and xenon isotopes decaying to magic isotopes of tin. Here we show the most extreme case of -particle preformation from the measurement of the decay of tellurium-104 (Te). With a half-life of 7.2
ns, Te is the fastest ground-state -emitting nucleus known so far. The deduced preformation demonstrates that the enhancement is greater for Te than for any other nucleus. One nuclear model that can explain our observation postulates that the particle can exist only in the low-nuclear-matter-density regions on the surface of the nucleus. The uniquely high preformation for Te is attributed to its relation to doubly magic tin-100 (
Sn), creating conditions conducive to form an particle.
大島 真澄*; 早川 岳人*; 浅井 雅人; 後藤 淳*; 篠原 宏文*
日本原子力学会誌ATOMO
, 68(6), p.361 - 365, 2026/06
多数の放射性同位元素を含む放射線スペクトルを、従来の分析法よりも高精度に解析する革新的な手法「スペクトル定量法(SDM法)」を開発した。この手法を、Ge検出器やシンチレーション検出器で測定された
線スペクトル、液体シンチレーションカウンターで測定された
線スペクトル、そして-同時計数スペクトルに適用した。更に、これらのスペクトルを統合し、その統合スペクトルにSDM法を適用することで、解析結果の精度が大幅に向上することを明らかにした。
SR studies of ion dynamics in the light of extended Kubo-Toyabe model伊藤 孝; 門野 良典*
Journal of Physics; Conference Series, 3222(1), p.012009_1 - 012009_7, 2026/05
The dynamical Kubo-Toyabe (dKT) function is extended to describe the spin relaxation under the coexisting dynamical and static internal magnetic fields. A detailed re-evaluation of the previous 
SR data in Na
CoO
using this function disfavors the conventional interpretation based on sodium-ion diffusion and instead supports the 
self-diffusion scenario. This also resolves the long-standing inconsistencies in the dKT-function-based SR studies on ion diffusion from the viewpoint of classical over-barrier-jump mechanism.
山本 将隆*; 日高 宏之*; 柳澤 達也*; 田端 千紘; 中尾 裕則*; 下村 晋*; 小野寺 秀也*; 網塚 浩*
Journal of the Physical Society of Japan, 95(5), p.053703_1 - 053703_4, 2026/05
被引用回数：0 パーセンタイル：0.00(Physics, Multidisciplinary)We report on the negative magnetization (NM) phenomenon characterized by a spontaneous magnetization antiparallel to an applied magnetic field in an antiferromagnetic (AFM) carbide TbNiC. The NM phenomenon in this compound is observed in the AFM state with a field cooling process at low magnetic fields below 500 Oe. The monotonic decrease in magnetization below the Neel temperature of 25 K observed in temperature dependence measurement of magnetization for TbNiC cannot be explained by Neel's classical theory of ferrimagnetism. We propose a novel ferrimagnetic model in which the NM originates from phase coupling between charge density wave and AFM orders.
Kreinder, B.; Cox, I.*; Grzywacz, R.*; 西尾 勝久; 他24名*
Nuclear Instruments and Methods in Physics Research A, 1085, p.171298_1 - 171298_7, 2026/05
被引用回数：0 パーセンタイル：0.00(Instruments & Instrumentation)In recent experiments, inorganic scintillators have been used to study the decays of exotic nuclei, providing an alternative to silicon detectors and enabling measurements that were previously impossible. However, proper use of these materials requires us to understand and quantify the scintillation process, specifically in response to very heavy nuclei. In this work, we show a simplified method based on the models of Birks (1951) and Meyer and Murray (1962) to parametrize the light output of inorganic scintillators in response to beams of energetic heavy ions over a broad range of energies. We test the accuracy of our parametrization approach by calculating light output and quenching factors for various ions and comparing them with experimental data from Lutetium Yttrium Orthosilicate (LYSO:Ce), a common inorganic scintillator. The Meyer-Murray model suggests that, for sufficiently heavy ions at high energies, the majority of the light output is associated with the creation of delta electrons, which are induced by the passage of the beam through the material. These delta electrons dramatically impact the response of detection systems when subject to ions with velocities typical of beams in modern fragmentation facilities. To illustrate this, we also present a qualitative estimate of the effects of delta rays on overall light output using the Birks-Meyer-Murray parametrization. The approach presented herein will serve as a basic framework for further, more rigorous studies of scintillator response to heavy ions. This work is a crucial first step in planning future experiments where energetic exotic nuclei are interacting with scintillator detectors.
石 禎浩*; 上杉 智教*; 森 義治*; 西尾 勝久
Physical Review Accelerators and Beams (Internet), 29(5), p.050101_1 - 050101_14, 2026/05
被引用回数：0 パーセンタイル：0.00(Physics, Nuclear)In heavy-ion accelerators used for radioactive isotope production, the accelerated beam is typically directed onto a target and then discarded in a beam dump. To make more efficient use of the beam, recycling of the beam passed through the target is proposed in the framework of the so-called energy recovery internal target (ERIT). In the ERIT system, the target is irradiated by a circulating beam, while the energy lost in the target is recovered using rf cavities. So far, such a system has been realized only for proton beams. Here, an ERIT system for heavy-ion beams is demonstrated for the first time. A major challenge is the circulation of ions with multiple atomic charge states. After passing through the target, ions rapidly reach an equilibrated charge-state distribution, independent of the initial charge state. This stochastic charge-state conversion (SCSC) leads to rapid beam-emittance growth. To mitigate this effect, we develop a method to match the closed orbits and betatron functions of different charge states at the target location, based on a scaling fixed-field alternating-gradient (FFA) lattice. We present the design of such an FFA ring and show, through 6D beam-tracking simulations, that the transverse emittance growth induced by SCSC can be significantly reduced over a practical number of turns, whereas longitudinal emittance growth remains significant and is discussed separately.
川田 拓哉*; 山本 慧; 河野 浩*; 林 将光*
Proceedings of SPIE, Vol.14081, p.140810M_1 - 140810M_6, 2026/05
In this work, we show both experimentally and theoretically that the electromagnetic fields dominate the charge current response of a ferromagnet/heavy metal multilayer deposited on top of a LiNbO
substrate under SAW excitation. Despite travelling much slower than the light in vacuum, the SAW-induced evanescent electric field turns out to have a transverse component that remains unscreened by conduction electrons and permeates through the film stack, causing a sizable ac electric current. The ac spin current generated through the spin-Hall effect combined with a magnetoelastic oscillation of magnetization leads to a rectified dc voltage signal of order 10 uV. The transverse electric field is naturally accompanied by a magnetic field, which is calculated to be as large as 1 uT. We clarify the relation between the validity of electrostatic approximation and the presence of non-negligible transverse fields. The work reveals the electromagnetic origin of acoustic spin-Hall effect and sheds light on the potential relevance of piezoelectricity in spintronic applications.
Sb with an ordered honeycomb network今津 毅士; 古谷 直也*; 足立 匡*; 工藤 一貴*; 今井 剛樹*; 御領 潤*
Journal of the Physical Society of Japan, 95(4), p.044704_1 - 044704_7, 2026/04
被引用回数：0 パーセンタイル：0.00(Physics, Multidisciplinary)空間反転対称性を破る結晶構造をもつ蜂の巣格子超伝導体BaPtAsSbは超伝導転移温度のx依存性が非単調な振る舞いを示す。更にミューオンスピン緩和実験によりSbエンド(
=1)において自発磁場が観測され、時間反転対称性を破る超伝導状態が実現している可能性がある。BaPtAs(=0), BaPtSb(=1)の第一原理計算を行い、バンド構造を再現する有効強束縛模型を用いてギャップ方程式と凝縮エネルギーの解析を行い、安定となる超伝導対称性を議論した。その結果、BaPtAs(=0)では時間反転対称性のある従来型のs波超伝導とf波超伝導が安定化し、BaPtSb(=1)では時間反転対称性を破るカイラルd波状態が広く安定化することがわかった。この結果はミューオンスピン緩和実験とも整合する。また本論文で得られた知見は六方晶におけるカイラル超伝導相の探索に重要な指針を与える。
森 道康; 小椎八重 航*; 前川 禎通*
Physical Review B, 113(13), p.134505_1 - 134505_8, 2026/04
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)Josephson diode effect between two singlet superconductors separated by the Rashba system is studied theoretically. The coupling energy of two superconductors is analytically calculated using a tunneling Hamiltonian with a one-dimensional model. In a magnetic field perpendicular to an applied current, we obtain a coupling energy proportional to the applied current and magnetic field. This makes the critical current asymmetric with respect to the current or the magnetic field, i.e., Josephson diode effect. More importantly, depending on a distance between the superconducting electrodes 
, the Josephson diode effect changes its magnitude and sign. The magnitude is inversely proportional to a band split caused by the spin-orbit interaction. Since is experimentally controllable, the Josephson diode effect can be optimized by tuning of .
徳永 陽; 鈴木 通人*; Kr
mer, S.*; 酒井 宏典; 神戸 振作; 播磨 尚朝*; 青木 大*; Horvati
, M.*; Sheikin, I.*
Physical Review B, 113(14), p.L140406_1 - L140406_7, 2026/04
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)We report low-temperature 
In nuclear magnetic resonance (NMR) study of the prototypical heavy-fermion compound CeIrIn in high magnetic fields applied close to the crystallographic 
axis. For this orientation, a field-induced transition was previously reported to take place at about 28~T. Although we do not observe any change of the NMR spectrum above the transition, the intensity of the NMR lines drastically decreases as a consequence of a considerable shortening of the 
relaxation time. In addition, shows a pronounced maximum at the transition. Taking into account previous high-field de Haas-van Alphen results in conjunction with band-structure calculations, our NMR results are most naturally explained by the field-induced transition into an antiferromagnetic state with the propagation vector 
and magnetic moments aligned antiferromagnetically along the axis.
Briscoe, A. D.*; Smallcombe, J.; 他60名*
Physical Review C, 113(4), p.044317_1 - 044317_10, 2026/04
被引用回数：0 パーセンタイル：0.00(Physics, Nuclear)The production of 
Os and Re was investigated in experiments performed at the Accelerator Laboratory of the University of Jyvaskyla. New decay chains assigned to 
Os were identified at beam energies of 310 and 330 MeV. These findings are compared with previous studies claiming the observation of Os and 
W.
Zn北澤 崇文; 志村 恭通*; 鬼丸 孝博*; 土田 駿*; 久保 勝規; 芳賀 芳範; 酒井 宏典; 常盤 欣文; 神戸 振作; 徳永 陽
Physical Review Research (Internet), 8(2), p.023009_1 - 023009_14, 2026/04
We investigated electron-nuclear spin entanglement in the paramagnetic ground state of the Ho-based cubic compound HoCoZn. From analyses of magnetization and specific heat data, we determined the cubic crystalline electric field (CEF) parameters, the magnetic exchange constant, and the hyperfine coupling constant between the 4
magnetic moment and the 
Ho nuclear spin. Our results show that the 
CEF ground state is split by the hyperfine coupling, with an energy width of 1.3~K at 0~T, and that the true paramagnetic ground state is a quasi-sextet arising primarily from entanglement between the -electron effective spin 
and the Ho nuclear spin 
. We further demonstrate that, depending on the CEF parameters, the paramagnetic ground state can switch to an electron-nuclear coupled dectet. These findings underscore the importance of accurately identifying the electron-nuclear level scheme for understanding the low-temperature properties of rare-earth compounds containing spin-active nuclei.
Rn/At generator田中 皐*; 清水 悠介*; 井田 朋智*; 鷲山 幸信*; 西中 一朗*; 浅井 雅人; 瀬川 麻里子; 横山 明彦*
Radiochimica Acta, 114(3), p.221 - 229, 2026/04
被引用回数：0 パーセンタイル：0.00(Chemistry, Inorganic & Nuclear)医療用放射性同位元素Atを製造・供給するためのRn/Atジェネレータシステムを開発している。本研究では、Rn/AtジェネレータシステムにおけるRnの気相回収条件を調査するため、溶液中のRnの溶解状況を解析した。硝酸-塩酸混合液中でのBiターゲットの溶解とそれに続く中和により、Rn回収効率が向上することが示された。気相Rn回収率は88%に達し、利用可能なAtの50%が回収されており、今後さらなる向上が期待される。
榊原 涼太郎*; 寺澤 知潮; 河内 泰三*; 福谷 克之; 伊藤 孝寛*; 乗松 航*
Small Methods, 10(8), p.e01889_1 - e01889_12, 2026/04
被引用回数：0 パーセンタイル：0.00(Chemistry, Physical)Fabrication of two-dimensional (2D) transition metal oxides has gained considerable attention due to their unique crystal structures and physical properties distinct from their bulk counterparts. Intercalation of foreign elements into the graphene/SiC(0001) interface is a possible approach for achieving this, as it enables the confinement and arrangement of atoms within the 2D interface. However, while various 2D metals and their compounds have been synthesized at the graphene/SiC interface, the fabrication of 2D transition metal compounds remains challenging. This difficulty arises from the high reactivity of transition metals such as Fe, Co, and Ni, which readily form carbides and silicides with the host material. In this work, the successful fabrication of a uniform 2D iron oxide at the graphene/SiC interface is demonstrated through the simultaneous intercalation of Fe and O. Direct observation using atomic-resolution electron microscopy revealed that the crystalline 2D iron oxide is encapsulated by graphene and forms a sharp interface with the SiC substrate. M
ssbauer spectroscopy measurements suggest that the 2D iron oxide exhibits a magnetic ordering at low temperatures. These findings suggest another strategy for synthesizing 2D transition metal oxides, opening new avenues for the advancement of 2D magnetic materials.
