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Cd
廣瀬 雄介; 本多 史憲*; 土塔 寛*; 河村 直己*; Kvashnina, K. O.*; Amidani, L.*; Uhl
ov
, K.*; Koloren
, J.*; Havela, L.*
Physical Review B, 113(24), p.L241103_1 - L241103_6, 2026/06
The regime of valence fluctuations, known from anomalous rare-earth systems with slow fluctuations between two different fn states, has not yet been identified by microscopic techniques at any Uranium compound. The reason may be in the predominant band character of U intermetallic compounds. Here we present U-L3 and M4 X-ray absorption spectra taken on UPdCd, which is a heavy-Fermion antiferromagnet. Although it has only one type of U site, the spectra obtained in the High Energy Resolution Fluorescence Detection mode display two edges, each associated with different valence states, 5f2 and 5f3. This is strongly suggestive of slow f2 - f3 fluctuations on the timescale longer than the characteristic time of the spectroscopy technique. Unlike 4f systems in which such fluctuations lead to a destruction of magnetism due to involvement of one non-magnetic state, the f2 and f3 states in U are both possibly magnetic, allowing for the magnetic ordering in the fluctuating state. Such a new situation can bring more light into emergent phenomena observable in U systems at the verge of 5f localization.
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：0In 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.
magnetic order with spatially alternating spin scalar chirality in overdoped Co
TaSCho, W.*; Park, P.*; Kim, C.*; An, Y.*; 飯田 一樹*; 梶本 亮一; Matin, S.*; Sibille, R.*; Crooker, S. A.*; Park, J.-G.*
Physical Review B, 113(17), p.174410_1 - 174410_14, 2026/05
被引用回数：0Co
TaS (
) exhibits a spontaneous Hall effect from spin texture in antiferromagnets, with a tetrahedral triple-Q () order and uniform spin scalar chirality. Upon Co overdoping (
), it undergoes a shift in magnetic ordering vectors from 
to 
. Interestingly, the spontaneous Hall effect disappeared in the overdoped regime, which was originally attributed to the loss of order. However, a question remains whether a new type of order can exist with alternating chirality in the overdoped regime. To address this, we investigated CoTaS using inelastic neutron scattering (INS), neutron diffraction, and optical dichroism, and found that INS data and spin-wave simulations support a order with alternating chirality. Moreover, neutron diffraction data show field-independent Bragg peaks, while linear dichroism detects no in-plane anisotropy, consistent with threefold rotation symmetry. Our data support the scenario of an alternating-chirality order in CoTaS, cancelling the spontaneous Hall effect. This study highlights a combined neutron-optical approach to identify complex spin textures.
-iron at high pressures determined using 
neutron diffraction青木 勝敏*; 高野 将大*; 福山 鴻*; 鍵 裕之*; 町田 晃彦*; 齋藤 寛之*; 服部 高典; 佐野 亜沙美; 舟越 賢一*
Physical Review B, 113(18), p.184440_1 - 184440_6, 2026/05
被引用回数：1体心立方(bcc)-鉄の磁気モーメントの温度依存性をその場中性子粉末回折法を用いて、約2GPaおよび6GPaの圧力下で300
950Kの範囲において調べた。磁気散乱の相対寄与を高めるため、中性子散乱長が天然Feの約半分である
Fe同位体が用いられた。キュリー温度(
)は、2.1GPa, 6.0GPa, 6.7GPaでそれぞれ946(30)K、838(50)K、740(40)Kと決定され、(K) = 1043 - 49(7)
+ 1.3(1.2)
で表される磁気相境界が決定された。6.7GPaで加熱すると、磁気転移に続いて
構造転移が観測された。この結果は、磁気相境界が相境界の低温側に位置することを示している。したがって、転移は、常磁性bcc鉄から常磁性fcc鉄への構造変化に対応する。
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：0We 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.
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：0We studied the cubic double perovskite BaCaOsO
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.
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 .
Prestwood, D.*; 吉川 貴史; 齊藤 英治; 他15名*
Physical Review B, 113(13), p.134410_1 - 134410_12, 2026/04
被引用回数：1 パーセンタイル：0.00(Materials Science, Multidisciplinary)We study a thin-film yttrium iron garnet sample that exhibits magnetic stripe domains due to a small perpendicular magnetic anisotropy. Using wide-field magneto-optic Kerr effect measurements we reveal the domain pattern evolution as a function of applied field and discuss the role of cubic anisotropy in the domain formation. Rich magnon spectra are observed in the stripe domain states, with a range of excitation conditions providing distinct spectra. The measurements are interpreted using micromagnetic simulations to provide the spatial profiles of each resonance mode. We further simulate domain patterns and resonance spectra accounting for the cubic anisotropy, with good correlation to experiment. This study highlights how noncollinear magnetic domain structures can host complex resonant behavior in a low-damping magnetic material, with potential use in future magnonic applications.
松村 拓輝*; 徳永 陽; 酒井 宏典; 神戸 振作; 木俣 基; 他14名*
Physical Review B, 113(9), p.094506_1 - 094506_12, 2026/03
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)Spin-triplet superconductivity is an intriguing quantum coherent state with both spin and orbital degrees of freedom, which holds significant potential for future applications in quantum technology. However, how the spin of the triplet pairs responds to an external magnetic field remains poorly understood. This is mainly due to the absence of suitable spin-triplet superconductors. Here, we report results of Knight-shift and ac-susceptibility measurements on UTe. We demonstrate that the spin susceptibility, which slightly decreases compared to the normal-state value below the superconducting transition temperature 
, is rapidly restored and nearly recovers to the normal-state values around 5 T, well below the SC upper critical field 
when the magnetic field is applied along the axis.
Valet, T.*; 山本 慧; Pigeau, B.*; de Loubens, G.*; Klein, O.*
Physical Review B, 113(10), p.L100410_1 - L100410_6, 2026/03
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)In the context of a growing interdisciplinary interest in the angular momentum of wave fields, the spin-wave case has yet to be fully explored, with the extensively studied notion of spin transport being only part of the broader picture. Here we report experimental evidence for non-zeromagnon orbital angular momentum inside magnetic disk, by resolving the frequency splitting between magnon modes with counter-rotating wavefronts and thereby avoiding formation of azimuthal standing waves. This requires an unambiguous formulation of spin and orbital angular momenta for spin waves, which we provide in full generality taking advantage of a systematic application of quantum field theory techniques as detailed in an associated article. The results unequivocally establish magnetic dipole-dipole interactions as a magnetic-field controllable spin-orbit interaction for magnons. Our findings open a new research direction, leveraging the spectroscopic readability of angular momentum for azimuthal spin waves and other related systems.
Valet, T.*; 山本 慧; Pigeau, B.*; de Loubens, G.*; Klein, O.*
Physical Review B, 113(10), p.104437_1 - 104437_17, 2026/03
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)In the context of an ever-expanding experimental and theoretical interest in the magnetization dynamics of mesoscopic magnetic structures, both in the classical and quantum regimes, we formulate a low-energy field theory for the linear spin waves in finite and textured ferromagnets and we perform its constrained canonical quantization. The introduction of a manifestly gauge invariant Lagrangian enables a straightforward application of the Noether's theorem. Taking advantage of this in the context of a broad class of axisymmetric ferromagnets of special conceptual and experimental relevance, a general expression of the conserved and quantized spin-wave total angular momentum is rigorously derived, while separate conservation and quantization of its orbital and spin components are established for a more restricted class of uniaxial exchange ferromagnets. Further particularizing this general framework to the case of axially saturated magnetic thin disks, we develop a semi-analytic theory of the low frequency part of the exchange-dipole azimuthal spin-wave spectrum, providing a powerful theoretical platform for the analysis and interpretation of magnetic resonance experiments on magnetic microdots as further demonstrated in a joint paper.
藤原 理賀; 萩原 雅人; 石角 元志*; Sari, D. P.*; 渡邊 功雄*; 髭本 亘; 田端 千紘; 金子 耕士
Physical Review B, 113(6), p.064409_1 - 064409_8, 2026/02
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)We report a field-induced quantum first-order transition in the antiferromagnet KCoPO
HO. Using highly oriented microcrystals with 
, polarized neutron diffraction directly reveals coexistence of an incommensurate cycloid and a commensurate collinear state, together with a discontinuous jump of the ordering wave vector from incommensurate to commensurate. Magnetization and specific heat show a step and a collapse of the 
anomaly near 
~T with no measurable hysteresis, while LF-
SR detects two-component relaxation and slow fluctuations around 
. The 
-
phase diagram exhibits a narrow coexistence region. Symmetry of space group 
constrains the DM vector to the 
plane and, together with XY anisotropy, nearly degenerates the incommensurate and commensurate states, enabling a first-order switch in field. KCoPOHO thus serves as a platform for quantum first-order transitions in frustrated magnets.
Fe
O
Lenander, E. Y.*; Nielsen, F. B.*; Lass, J.*; Hansen, U. B.*; Krighaar, K. M. L.*; Preuss, A.*; Weber, T.*; Enderle, M.*; Jacobsen, H.*; Stuhr, U.*; et al.
Physical Review B, 113(1), p.014424_1 - 014424_14, 2026/01
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)The frustrated magnet BiFeO has been reported to exhibit complex spin dynamics coexisting with conventional spin wave excitations. The magnetic Fe
(
) ions are arranged into a distorted two-dimensional Cairo pentagonal lattice with weak couplings between the layers, developing long-ranged noncollinear antiferromagnetic order below 245 K. In order to enable studies and modeling of the complex dynamics close to 
, we have reexamined the magnetic excitations across the complete energy scale (
meV) at 10 K. We discover two distinct gaps, which can be explained by introducing, respectively, easy axis and easy plane anisotropy on the two unequivalent Fe sites. We develop a refined spin Hamiltonian that accurately accounts for the dispersion of essentially all spin-wave branches across the full spectral range, except around 40 meV, where a splitting and dispersion are observed. Polarization analysis shows that the system has magnetic anisotropic fluctuations, consistent with our model. A continuum of scattering is observed above the spin wave branches and is found to principally be explained by an instrumental resolution effect. The full experimental mapping of the excitation spectrum and the refined spin Hamiltonian provides a foundation for future quantitative studies of spin waves coexisting with unconventional magnetic fluctuations in this frustrated magnet found at higher temperatures.
H
studied by 
Fe nuclear resonant inelastic scattering河智 史郎*; 平賀 晴弘*; 山浦 淳一*; 飯村 壮史*; 中村 博樹; 筒井 智嗣*; 依田 芳卓*; 町田 昌彦; 細野 秀雄*; 小林 寿夫*
Physical Review B, 113(2), p.024519_1 - 024519_7, 2026/01
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)LaFeAsOH (
)の高濃度水素化物イオン置換領域における鉄のフォノンダイナミクスを調べるため、Fe核共鳴非弾性散乱測定を、超伝導および反強磁性の基底状態をそれぞれ示す
と0.51の2種類の多結晶試料に対して、5300Kの広い温度範囲で実施した。得られた非弾性散乱スペクトルは、両組成間に顕著な差異を示した。Feのフォノン状態密度(PDOS)は、では15meVに顕著なピークを示す一方、
ではこのピークが消失している。密度汎関数理論(DFT)計算により、この15meVのPDOSピークはAs原子を介した最近接方向に沿ったFe原子の光学振動モードに関連していることが支持された。さらに計算は、で15meVのPDOSピークが抑制される原因が面内の電子的不等価性に起因することを示唆している。これらの結果は、磁気および構造秩序を示す組成では、広い温度範囲にわたり電子ネマティシティの兆候が持続する可能性がある一方、超伝導を示す組成ではその兆候がほとんど存在しないことを示唆している。
山根 結太*; 中根 丈太郎*; 荒木 康史; 家田 淳一
Physical Review B, 113(1), p.014421_1 - 014421_7, 2026/01
被引用回数：1 パーセンタイル：0.00(Materials Science, Multidisciplinary)We theoretically investigate emergent impedance induced by domain-wall dynamics in antiferromagnets. Emergent impedance, arising from a combined action of spin-transfer torque and spinmotive force, was previously predicted and observed in spiral magnets. Here we develop a formalism for the electrical response of an antiferromagnetic domain wall under ac currents, and obtain analytical expressions for the resulting emergent impedance. We find that two dynamical modes play separate roles in the emergent impedance: Translational motion of the domain-wall center generates a contribution proportional to its velocity, analogous to that arising from the corresponding motion of a spiral magnet. Another contribution, unique to antiferromagnetic domain walls, originates from the time-dependent canting of the sublattice magnetizations localized within the moving domain wall, whose magnitude is inversely proportional to the antiferromagnetic exchange coupling constant. The competition between these two distinct contributions determines the sign and magnitude of the imaginary part of the emergent impedance at sub-resonant frequencies. Our results provide a fundamental insight into electron transport in antiferromagnets, and open avenues for novel antiferromagnet-based spintronics devices.
清水 悠晴*; 橘高 俊一郎*; 河野 洋平*; 中村 翔太*; 芳賀 芳範; 山本 悦嗣; 町田 一成*; 網塚 浩*; 榊原 俊朗*
Physical Review B, 112(24), p.245157_1 - 245157_10, 2025/12
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)We report the results of high-resolution dc magnetization and specific heat measurements on the unconventional superconductor UBe.Suppression of the non-Fermi-liquid behavior under field and a nontrivial fifth-order magnetic susceptibility were observed at low temperatures, suggesting the Fermi-surface reconstruction accompanying the crossover from non-Fermi-liquid to Fermi-liquid state in UBe.
Spitz, L.*; Razpopov, A.*; Biswas, S.*; Lane, H.*; Nikitin, S. E.*; 飯田 一樹*; 梶本 亮一; 藤田 全基*; 新井 正敏*; Mourigal, M.*; et al.
Physical Review B, 112(18), p.184302_1 - 184302_18, 2025/11
被引用回数：1 パーセンタイル：36.38(Materials Science, Multidisciplinary)CuGeO has long been studied as a prototypical example of the spin-Peierls transition in a 
Heisenberg chain. Despite intensive investigation of this quasi-one-dimensional material, systematic measurements and calculations of the phonon excitations in the dimerized phase have not to date been possible, leaving certain aspects of the spin-Peierls phenomenon unresolved. We perform state-of-the-art density functional theory (DFT) calculations to compute the electronic structure and phonon dynamics in the low-temperature dimerized phase. We also perform high-resolution neutron spectroscopy to measure the full phonon spectrum over multiple Brillouin zones. We find excellent agreement between our numerical and experimental results that extend to all measurement temperatures. Notable features of our phonon spectra include a number of steeply dispersive modes, nonmonotonic dispersion features, and specific phonon anticrossings, which we relate to the mode eigenvectors. By calculating the magnetic interactions within DFT and studying the effects of different phonon modes on the superexchange paths, we discuss the possibility of observing spinphonon hybridization effects in experiments performed both in and out of equilibrium.
玉造 博夢; 小澤 竜也*; 満田 節生*; 藤原 理賀; 金城 克樹*; 那波 和宏*; Wu, H.-C.*; 佐藤 卓*; 矢野 真一郎*
Physical Review B, 112(18), p.184115_1 - 184115_8, 2025/11
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)Recently, applying a uniaxial stress 
of only 40 MPa along the 
axis to a single domain structure of MnP has been found to modify the fractional coordinates of each ion irreversibly with respect to , leading to the formation of crystal domains rotated by 
around the 
axis. To reveal the process of this unusual domain formation, we measure time evolution of magnetization due to the crystal domain formation and perform neutron diffraction measurements under . Threshold stress causing domain formation increases as temperature () decreases, and magnetization along the axis (
) increases over time on the order of hours with a -dependent relaxation time. These results suggest that this domain formation by is thermally activated. Based on these results, we achieve controlling the crystal domain formation by regulating and . Moreover, although increases on the order of hours, spatial disorder is not observed during the change in the fractional coordinates of each ion in the neutron diffraction measurement. This work paves the new way for a crystal domain engineering method by using , affecting both fundamental material science and the industrial utilization of materials.
吉村 宣倖*; 外山 毅*; 菖蒲田 義博
Physical Review Accelerators and Beams (Internet), 28(10), p.101003_1 - 101003_39, 2025/10
被引用回数：0 パーセンタイル：0.00(Physics, Nuclear)大強度陽子加速器施設(J-PARC)の主リング加速器(MR)の安定運転において、陽子ビームの横方向振動数の色収差と振動安定化のためのフィードバック用パラメータの最適化が重要である。特に、MRのような広い色収差を持つ陽子ビームの場合、ビーム自身の相互作用(空間電荷効果)の影響も考慮する必要がある。今回、色収差と空間電荷効果の関係を調査するため、ビームを構成する粒子がそろった運動とばらばらな運動を繰り返す現象に注目し、その振動周期を調査した。その結果、空間電荷効果が色収差を介してその周期に大きな影響を与える一方で、色収差とその最大振動数の関係は空間電荷効果の影響を受けないことが理論的・実験的に明らかになった。これらの知見は、陽子ビームが直接相互作用する直接的空間電荷効果、加速器の真空容器を介して相互作用する間接的空間電荷効果、ビームの不安化を引き起こす抵抗性真空容器との効果、全てを考慮したシミュレーションでも確認できた。さらに、空間電荷効果と抵抗性真空容器が引き起こす振動モードを調査した結果、直接的空間電荷効果だけではビームは不安定化するが、間接的空間電荷効果を含めて考慮するとビームを安定化できることを明らかにできた。これにより、「空間電荷効果はビームを安定化するのか不安定化するのか」というビーム力学的課題に一定の結論を得た。なお、本論文は、米国物理学会の卓越した論文に選出された。
B日高 宏之*; 柳澤 達也*; 田端 千紘; 今 布咲子*; 網塚 浩*; 清水 悠晴*; 青木 大*
Physical Review B, 112(14), p.144418_1 - 144418_6, 2025/10
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)A uranium-based metallic compound UNiB with orthorhombic structure exhibits an antiferromagnetic (AFM) ordering at 
= 20.4 K. Although an electric current-induced magnetization below has been observed in this compound [H. Saito et al., J. Phys. Soc. Jpn. 87, 033702 (2018)], its underlying mechanism remains controversial. In this study, we measured thermal expansion and magnetostriction along the a-axis under magnetic field up to 14 T applied within the -plane to investigate rotational symmetry of a magnetic field-temperature phase diagram in UNiB. From the phase diagrams constructed under various -angles between and , it is suggested that the - phase diagram practically exhibits six-fold rotational symmetry in the plane despite the orthorhombic crystal structure, which would be attributed to quasi-hexagonal structure formed by U ions with small orthorhombic distortion.
