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Chen, J.*; 山本 慧; 他13名*
Physical Review Letters, 136(5), p.056702_1 - 056702_8, 2026/02
The recently developed van der Waals magnets provide a promising platform for spintronics and magnonics. Here, we report the observation of surface magnon propagation in the van der Waals antiferromagnet CrSBr. We find a nearly unidirectional propagation of antiferromagnetic magnon modes, which emerge near the anticrossing of the optical and acoustic magnon bands, in agreement with our theory of magnetostatic waves in antiferromagnets. The propagation direction can be reversed by switching the magnetic field. The observed antiferromagnetic magnons operate in the gigahertz regime due to the weak interlayer exchange coupling. Our results open the pathway for nonreciprocal magnonic applications based on van der Waals antiferromagnets at easily-accessible microwave frequencies.
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
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.
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
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、5
300K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。
-wave 
baryonsSu, N.*; Chen, H.-X.*; Gubler, P.; 保坂 淳
Physical Review D, 113(1), p.016005_1 - 016005_7, 2026/01
Using the QCD sum rule method, we investigate the mass splitting for the spin-orbit partner states of the 
baryon assuming that it is a -wave excitation with 
. This study is an extension of a previous work, in which the masses of these states were estimated with uncertainties too large to extract the reliable mass splitting. In the present study, by directly formulating a sum rule for the mass splitting, we obtain an improved prediction, 
MeV. This result provides a more quantitative insight into the spectrum of -wave baryons and serves as a useful reference for future experiments.
quartz irradiated with swift heavy ions; Thickness and edge effects石川 法人; 田口 富嗣*; 小河 浩晃; Toimil-Molares, M. E.*; Trautmann, C.*
Physical Review Materials (Internet), 10(1), p.016001_1 - 016001_7, 2026/01
結晶性SiO(石英)試料に1.64GeVおよび200MeVのAuイオンを照射し、イオントラック形成に由来する照射誘起ナノ構造を透過型電子顕微鏡(TEM)を用いて調査した。解析の結果、通常観察される均一な非晶質イオントラックだけでなく、同心円状のコア-ハロー構造(イオン飛跡に沿った低密度コアとハロー損傷領域)を持つトラックも観察された。後者のタイプのトラックは、厚さが50nm未満の薄い試料領域でのみ確認され、こうした低密度コアを持つトラックの形成には薄い試料が必要条件であることが示唆された。さらに、試料端部ではクレーター状の構造を持つピット状トラックも確認された。表面を含む試料の形態が、複雑なナノ構造の形状に影響を与えていることが強く示唆された。これらの結果について、電子スパッタリングなどの表面現象や、試料の厚さおよび試料端効果の観点から議論した。
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
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.
Ou-Yang, Z.-X.*; Gubler, P.; 岡 眞*; Wang, G.-J.*; Wu, J.-J.*
Physical Review D, 112(11), p.114034_1 - 114034_13, 2025/12
We propose an extension of the QCD sum rules, termed the resonance sum rules, to access resonance poles in the complex energy plane. By strategically introducing a contour in the complex plane and conformal mapping, the method intends to reach resonance poles on the second Riemann sheet. To validate this approach, we apply resonance sum rules to the square-well potential model, for which the pole locations are known. The analysis demonstrates a successful extraction of the pole positions and residues for both the S-wave and P-wave resonances. The results are in good agreement with the analytic solutions, with discrepancies within 5% for the pole positions and 20% for the residues. This framework provides a basis for future applications to realistic hadronic resonances, promising new insights into spectral properties of QCD.
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
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.
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
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.
藤井 大輔; 岩中 章紘*; 田中 満*
Physical Review D, 112(9), p.094051_1 - 094051_12, 2025/11
本研究では、トップダウンホログラフィックQCDにおいて得られる重力形状因子を用いて、パイオン内部のエネルギー密度および応力分布を解析する。特に、核子においてインスタント形式で示されていたように、閉じ込め圧力がQCDのスケール異常によって支配されるという特徴が、パイオンにおいてもライトフロント形式で成り立つことを示す。さらに、このホログラフィック模型で記述されるラージ
極限においては、スカラーグルーボールが閉じ込め圧力を媒介する役割を担っていることが明らかになる。これらの結果は、ハドロンの安定性におけるスケール異常の普遍的な役割を支持するものである。
Arifi, A. J.; 鈴木 渓
Physical Review D, 112(9), p.094013_1 - 094013_18, 2025/11
本研究では、構成子クォーク模型を用いて、強磁場下における重いクォーコニウムの構造変化の解析を行う。磁場中のクォークのダイナミクスを記述する模型として、スピン固有状態の混合効果とクォークのランダウ準位の効果を取り込んだ非相対論的ハミルトニアンを採用する。2体シュレーディンガー方程式は、磁場中で現れる円筒対称性を尊重した円筒型ガウス展開法を用いて数値的に解く。ライトフロント波動関数(LFWF)密度を計算することで、その横方向および縦方向の構造を解析し、横方向運動量の広がりなどの特徴的な性質を明らかにする。縦方向の構造は模型の範囲ではわずかに変化するだけだが、そこで大きな影響を与える可能性のある補正についても説明する。さらに、励起状態の構造変化について説明し、LFWF密度の顕著な変化と、回避交差付近の状態再シャッフルを示す。これらの結果は、ハドロン構造が外部磁場に敏感であることを示し、相対論的なアプローチへの理解を深めるのに役立つ。
高木 慎弥*; 原田 壮太*; 有友 嘉浩*; 廣瀬 健太郎; 西尾 勝久
Physical Review C, 112(4), p.044607_1 - 044607_9, 2025/10
Actinide nucleus shows mass-asymmetric fission in low energy due to shell structure. The fission fragment mass distributions at high energy tend to have a symmetric shape due to smearing of the shell. On the other hand, the distribution can be changed by the neutron emission before fission, as it decreases the excitation energy of fissioning nucleus, thus revives the shell structure. In the so called multichance fission, neutron emission is considered at the ground state shape, and competition between fission and neutron emission is determined in the framework of statistical model. In the present work, we describe fission in the Langevin equations, and the neutron emission is treated all over the fission process. The calculation demonstrated experimentally observed mass distribution, characterized by the peak-to-valley ratio, for wide range of initial compound-nucleus excitation energy up to 60MeV. The results show that, while neutron emission dominates at the ground state shape, it occurs along the shape evolution down to the scission point.
江崎 蘭世; Go, G.*; Kim, S. K.*
Physical Review B, 112(10), p.104440_1 - 104440_10, 2025/09
In this study, we theoretically demonstrate that thermally excited magnons can induce scalar spin chirality (SSC) even in collinear spin systems. We show both numerically and analytically that the SSC increases with the magnitude of DMI and temperature and reveal that the magnon-induced SSC can achieve a magnitude comparable to those observed in non-coplanar spin configurations. These findings suggest that SSC plays a significant role even in collinear spin systems, providing new insights into the chiral physics of magnetic materials.
O
Prokhnenko, O.*; Nikitin, S. E.*; 金子 耕士; 田端 千紘; 廣瀬 雄介; 常盤 欣文; 芳賀 芳範; 藤田 全基; 野尻 浩之*; Anovitz, L. M.*; et al.
Physical Review B, 112(9), p.094402_1 - 094402_7, 2025/09
被引用回数：0 パーセンタイル：0.00The spin dynamics in the natural mineral aegirine, NaFeSiO, a member of the pyroxene family, was studied using elastic and inelastic neutron scattering. Magnetization and specific heat measurements as well as single-crystal neutron diffraction maps confirm two successive magnetic transitions at 8.8 and 5.8~K, consistent with previous studies. The observed spin-wave excitations emerge from the incommensurate magnetic Bragg peaks corresponding to the propagation vector 
, and extend up to energies of about 1.5 meV. In the low-temperature helical phase, the spin dynamics of the Fe
ions is well described by a simple linear spin-wave model. The observed excitations can be modeled using a spin Hamiltonian that includes three primary exchange interactions. Our results show that no single exchange interaction dominates the spin dynamics. The similar strengths of the intrachain and interchain couplings point to the fact that the magnetic interactions in aegirine are three-dimensional, rather than being confined along one direction. As a result, the system cannot be considered quasi-one-dimensional, as previously suggested, and calls for further investigations.
S
studied by X-ray magnetic circular dichroismVerma, V. K.*; 芝田 悟朗; 藤森 淳*; 他8名*
Physical Review B, 112(10), p.104444_1 - 104444_8, 2025/09
We have investigated the element specific magnetic characteristics of single-crystal FeCrS
using X-ray magnetic circular dichroism (XMCD). We have found that the Fe L2,3-edge XAS spectra do not exhibit clear multiplet structures, indicating strong hybridization between the Fe 3d and S 3p orbitals, leading to delocalized rather than localized electronic states. The Fe 3d and Cr 3d spin moments are antiferromagnetically coupled, consistent with the Goodenough-Kanamori rule. The orbital magnetic moments of Fe and Cr are determined to be -0.23 and -0.017 
B/ion, respectively. The large orbital magnetic moment of Fe is due to the d6 configuration under the relatively weak tetrahedra crystal field at the Fe site, and the delocalized Fe electrons maintain the orbital degree of freedom in spite of their itinerant nature. On the other hand, the octahedral crystal-field splitting of the Cr 3d level is large enough to result in the quenching of the orbital moment of the Cr ion in FeCrS.
岡田 和記; 和田 隆宏*; Carjan, N.*
Physical Review C, 112(3), p.034613_1 - 034613_11, 2025/09
Transport coefficients in the Langevin equation are essential for the dynamical analysis of nuclear fission. Two primary methods for calculating these coefficients exist: macroscopic and microscopic. Here we study the fission of 
U using a five-dimensional Langevin equation with a Cassini shape parameterization to examine how the choice of transport coefficients affects the distributions of fission fragment mass, quadrupole (
), octupole (
) and total kinetic energy (TKE). The results indicate that microscopic transport coefficients generate fragments with a broader range of deformation, which improves the agreement with experimental mass distributions for asymmetric fission modes. This improvement is found to be primarily due to the microscopic inertia tensor. To assess the effectiveness of the five-dimensional parameterization, the results are compared with those from lower-dimensional calculations. The Cassini parameter set 
is shown to properly describe both mass asymmetry and super-long symmetric fission. Furthermore, a rare type of hot fission is observed for heavy fragment masses of 
, characterized by a super-elongated, neck-shaped light fragment.
/
for the 19.40-MeV state in 
Be for studying the 
Be(
,
)Li
reaction relevant to the cosmological lithium problem岩佐 直仁*; 西尾 勝久; 廣瀬 健太郎; 牧井 宏之; Orlandi, R.; 洲嵜 ふみ; Smallcombe, J.; 他7名*
Physical Review C, 112(3), p.035801_1 - 035801_6, 2025/09
The Li(
He,
)Be(
)Li reaction was measured at 
(He) = 28 MeV for studying the Be(,)Li reaction, which is a Be destruction reaction in the big bang nucleosynthesis. Resonant states at 18.9
20.1 MeV in Be were populated by the Li(He,)Be reaction and decay protons to the ground (
) and first-excited states () in Li were well separated and measured. The resonance width 
and branching ratio / for the 19.40-MeV state in Be were deduced to be 342
112 keV and 11.2 3.5 5.0 (syst.)%, respectively. The 
Be(,)Li reaction cross section was deduced.
田中 満*; 藤井 大輔; 川口 眞実也*
Physical Review D, 112(5), p.054048_1 - 054048_18, 2025/09
本研究では、核子の重力形状因子、特に
形状因子と、それに関連する応力分布および内部力構造に対するQCDスケール異常の影響を解析する。解析には、スケール対称なカイラル摂動理論に基づいて構築されたスカーミオン模型を用いる。この模型では、現在のクォーク質量の効果を担うパイオンと、グルーオンの量子的寄与を反映するスカラー中間子の両方を組み込んでいる点が特徴である。スカラー中間子の質量を変化させることで、スケール異常のグルーオン成分が核子の力学的性質にどのように影響するかを調べる。その結果、グルーオンに由来するスケール異常は、核子の安定性条件を満たすうえで本質的な役割を果たし、閉じ込め圧力の生成にも寄与することが示された。また、の運動量移動依存性も計算し、その振る舞いが格子QCDの結果とよく一致することを確認した。
常盤 欣文; Opletal, P.; 酒井 宏典; 久保 勝規; 神戸 振作; 山本 悦嗣; 木俣 基; 淡路 智*; 佐々木 孝彦*; 青木 大*; et al.
Physical Review Letters, 135(13), p.136502_1 - 136502_6, 2025/09
UTeにおける軸方向の容易軸メタ磁性クロスオーバーが超伝導に及ぼす影響を、交流磁化率、磁化、および磁気熱量効果の測定によって調べた。高品質な単結晶試料において、5.6Tで超伝導状態内におけるメタ磁性に駆動された磁場誘起相転移を確認した。この相転移により高磁場超伝導状態が形成され、上部臨界磁場は12Tまで大幅に増大する。転移点でのエントロピーの急激な増加は秩序変数の自己再構成を示唆しており、多成分超伝導状態が外部摂動に適応するメカニズムを示している。
- and 
-decay spectroscopy of 
AuMi
t, J.*; Andel, B.*; Andreyev, A. N.; 他61名*
Physical Review C, 112(2), p.024328_1 - 024328_16, 2025/08
An - and -decay study of laser-ionized and mass-separated Au (
=79, 
=103) was conducted at the ISOLDE Decay Station at CERN. 
- analysis significantly extended the level scheme of the daughter nucleus Pt, identifying 125 new levels and 336 new -ray transitions. The -decay scheme of Au was also extended, an -decay branching ratio of 0.129(11)% was measured and a spin-parity assignment for the 
Ir ground state was proposed.
