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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.
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.
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 FeCr
S
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.
藤井 大輔; 中山 勝政*; 鈴木 渓
Physical Review D, 112(3), p.034020_1 - 034020_17, 2025/08
被引用回数：0 パーセンタイル：0.00磁場中の有限密度物質において、ディラックフェルミオンに由来するカシミール効果を理論的に解析する。特に、強い相互作用をもつディラック系における不均一な基底状態の候補として知られる「磁気二重カイラル密度波(MDCDW)相」におけるクォーク場に注目する。この相では、化学ポテンシャル・外部磁場・基底状態の空間的変調が複雑に干渉することで、カシミールエネルギーが距離に対して非自明な振動的挙動を示す。全カシミールエネルギーをランダウ準位ごとに分解することで、最低準位と高次準位のどちらが寄与するかによって、異なるタイプのカシミール効果が現れることが明らかになる。さらに、アップクォークとダウンクォークといったフェルミオンのフレーバー間の準位分裂に起因する特徴的な振る舞いも指摘する。
meson decay constants and distribution amplitudes in a self-consistent light-front quark modelArifi, A. J.; Choi, H.-M.*; Ji, C.-R.*
Physical Review D, 112(3), p.033009_1 - 033009_15, 2025/08
被引用回数：0 パーセンタイル：0.00In this study, we present a comprehensive analysis of decay constants and chiral-even and chiral-odd distribution amplitudes (DAs) up to twist 4 for the meson in the standard light-front quark model (LFQM) based on the Bakamjian-Thomas (BT) construction. For the meson, which possesses both longitudinal and transverse polarizations, two types of decay constants arises accordingly. We demonstrate that these decay constants can be self-consistently extracted from both local and nonlocal matrix elements in a manner independent of current components, polarizations, and reference frames. In particular, we emphasize the role of nonlocal matrix elements involving axial-vector and scalar currents, where mixing between two different decay constants; occurs. We show that this mixing is consistently resolved through the BT construction, ensuring the proper extraction of these decay constants. Additionally, we investigate the structure of chiral-even DAs and chiral-odd DAs beyond leading twists, and present their corresponding 
-moments and Gegenbauer moments. These results provide deeper insight into the nonperturbative structure of vector mesons and demonstrate the robustness and self-consistency of the LFQM based on the BT framework.
窪田 崇秀*; 鈴木 和也; Hirayama, Yoshiyuki*; Takahashi, Shigeki*; 高梨 弘毅
Physical Review Materials (Internet), 9(8), p.084408_1 - 084408_7, 2025/08
High-entropy alloys (HEAs) exhibit various physical properties, such as high microhardness for structured materials and high efficiency for catalysis. These features are recognized as a cocktail effect of five or more elements that stabilize a single-phase solid solution due to a high configurational entropy.
Saha, P. K.; 原田 寛之; 田村 文彦; 岡部 晃大; 吉本 政弘; 菖蒲田 義博; 沖田 英史; 小島 邦洸; 仲野谷 孝充; 畠山 衆一郎; et al.
Physical Review Accelerators and Beams (Internet), 28(7), p.074201_1 - 074201_23, 2025/07
In this research, the beam loss in the J-PARC 3-GeV Rapid Cycling Synchrotron (RCS) has been significantly mitigated at the designed 1 MW beam power. It was possible by identifying all beam loss sources and implementing appropriate measures based on numerical simulations and systematic beam studies. The major one includes of using a smaller size charge-exchange foil and optimizing the injection beam to minimize foil scattering uncontrolled beam loss, modifications of the transverse and longitudinal beam painting parameters to mitigate the high-intensity effects. The beam loss as compared to 1 MW trial operation in 2020 was 80% reduced and perfectly localized at the designated collimator area. The beam loss power is only less than 0.1 kW as compared to the collimator limit of 4 kW. As a result. the residual radiation throughout the ring is substantially reduced for achieving a sustainable operation of the RCS with nearly 99% availability.
高木 慎弥*; 有友 嘉浩*; 中島 滉太*; 岡田 和記; 廣瀬 健太郎; 西尾 勝久
Physical Review C, 112(1), p.014608_1 - 014608_7, 2025/07
被引用回数：0 パーセンタイル：0.00(Physics, Nuclear)Kinetic energy of individual fission fragment for actinide nuclei is, for example, important for evaluating the prompt-neutron spectrum in the laboratory system. It is experimentally known that kinetic energy for each fragment is constant at about 100 MeV for light fragments and that for heavy fragments decreases linearly with mass number. Most of the theoretical studies carried out so far attempted to calculate the total kinetic energy of both fragments, i.e. sum of the energies of two fragments, but the kinetic energy of each fragment was not analyzed in detail as far as we recognize. We have calculated them in thermal-neutron induced fission of 
Pu with a dynamical model using Langevin equations within a three-dimensional two-center parametrization. Also fission of 
Fm was investigated. It is calculated from the Coulomb energy at the scission point and the pre-scission kinetic energy. It is found that the pre-scission kinetic energy has about 2-4% contribution in the kinetic energy. The calculated results reproduce the trend of the experimental data.
関 祐一*; 藤森 伸一; 他10名*
Physical Review Letters, 135(4), p.046402_1 - 046402_7, 2025/07
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.
中山 昌勲*; 御手洗 光祐*; Placidi, L.*; 杉本 貴則*; 藤井 啓祐*
Physical Review Research (Internet), 7(3), p.033048_1 - 033048_9, 2025/07
Quantum machine learning has the potential to computationally outperform classical machine learning, but it is not yet clear whether it will actually be valuable for practical problems. While some artificial scenarios have shown that certain quantum machine learning techniques may be advantageous compared to their classical counterpart, evidence does not yet suggest that quantum machine learning has surpassed conventional approaches in dealing with standard classical datasets, such as the MNIST dataset. In contrast, dealing with quantum data, such as quantum states or circuits, may be the task where we can benefit from quantum methods. Therefore, it is important to develop practically meaningful quantum datasets for which we expect quantum methods to be superior. In this paper, we propose a machine learning task that is likely to soon arise in the real world: clustering and classification of quantum circuits. We provide a dataset of quantum circuits optimized by the variational quantum eigensolver.
magnetic orderings in a triangular lattice; Implications for multi- orderings in general two-dimensional latticesPark, P.*; Cho, W.*; Kim, C.*; An, Y.*; 飯田 一樹*; 梶本 亮一; Matin, S.*; Zhang, S.-S.*; Batista, C. D.*; Park, J.-G.*
Physical Review X, 15(3), p.031032_1 - 031032_29, 2025/07
Multi- magnetic structures on two-dimensional (2D) lattices provide a key route to realizing topological physics in 2D magnetism. A major experimental challenge is to unambiguously confirm their formation by excluding the possibility of topologically trivial multi-domain single- or double- magnetic orders, which cannot be distinguished using conventional diffraction techniques. Here, we propose that long-wavelength spin dynamics offers a universal diagnostic for triangular lattices: triple- orders that preserve rotational symmetry and single- or double- orders that break it exhibit qualitatively distinct anisotropies in their Goldstone mode velocities, stemming from fundamental differences in their underlying spin configurations. We validate this concept using the metallic triangular-lattice antiferromagnet Co
TaS, which hosts both a stripe-type single- state and a triple- tetrahedral ordering at different temperatures. Using inelastic neutron-scattering and spin dynamics simulations, we first refine the spin Hamiltonian by fitting the paramagnetic excitation spectra, allowing us to develop an unbiased model independent of magnetic ordering. We then show that the observed velocity profiles of the Goldstone modes agree with the high-temperature model's predictions: markedly anisotropic for the single- phase and near isotropic for the triple- phase. Importantly, this contrast persists across various exchange parameters, highlighting its model-independent nature and suggesting potential applicability to other 2D lattice systems. Beyond the long-wavelength regime, we present a substantial discrepancy between the measured and simulated magnon spectra exclusively in the triple- phase. We attribute this discrepancy to magnon energy renormalization arising from order-of-magnitude-enhanced magnon-magnon interactions in the triple- phase, due to its noncollinear configuration. This work provides universal insight into the dynamical properties of topological multi- magnetic orderings in 2D lattice structures, offering a broadly applicable diagnostic to distinguishing them from topologically trivial single- or double- counterparts. The unequivocal confirmation of the triple- structure in CoTaS further establishes it as a prominent material platform for exploring topological spin textures in the genuine 2D limit.
松下 太樹*; 小沢 耀弘*; 荒木 康史; 藤本 純治*; 佐藤 昌利*
Physical Review B, 111(24), p.245131_1 - 245131_11, 2025/06
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)We investigate the intrinsic spin Nernst effect (SNE), a transverse spin current induced by temperature gradients, in topological Dirac semimetals (TDSMs) and magnetic Weyl semimetals (MWSMs) with Ising spin-orbit coupling. The intrinsic SNE is described by the spin Berry curvature, which reflects the geometric nature of TDSMs and MWSMs. We clarified that the intrinsic SNE becomes significant when the Fermi energy is near, but slightly deviates from, the energy of the point nodes. In this situation, Bloch electrons with strong spin Berry curvature contribute to the SNE while avoiding carrier compensation between electrons and holes. We found that in TDSMs with small Fermi surfaces, the spin Nernst angle, which measures the efficiency of the SNE, is larger than that observed in heavy metals. This suggests that TDSMs with small Fermi surfaces can achieve efficient heat-to-spin current conversion. In MWSMs, variation in the magnitude of the exchange coupling with magnetic moments significantly changes the SNE, affecting both the direction and magnitude of the spin Nernst current. This implies that ferromagnetic transitions can be used to reverse the spin Nernst current. These results provide the fundamentals for future topological spin caloritronics.
町田 晃彦*; 齋藤 寛之*; 青木 勝敏*; 小松 一生*; 服部 高典; 佐野 亜沙美; 舟越 賢一*; 町田 真一*; 佐藤 豊人*; 折茂 慎一*
Physical Review B, 111(22), p.224413_1 - 224413_6, 2025/06
被引用回数：1 パーセンタイル：68.15(Materials Science, Multidisciplinary)Mn金属を高温高圧で水素化することにより形成される反強磁性Mn重水素化物、fcc
-MnDxとhcp
-MnDxの結晶構造と磁気構造をin-situ中性子粉末回折により調べた。重水素原子はfcc及びhcp金属格子の八面体格子間を部分的に占有していた。N
el温度は-MnD
で543(10)Kであった。-MnD
では、飽和磁気モーメントは0.82(1)
、Nel温度は347(3)Kであった。-MnDと-MnDについて決定されたNel温度は、以前の研究で提案されたそれぞれのSlater-Pauling曲線によって予測されたものと一致した。更新されたNel温度は、電子バンド構造計算に基づくより正確なSlater-Pauling曲線の開発に示唆を与える。
Co
)Sn studied by SRCai, Y.*; Yoon, S.*; Sheng, Q.*; Zhao, G.*; Seewald, E. F.*; Ghosh, S.*; Ingham, J.*; Pasupathy, A. N.*; Queiroz, R.*; Lei, H.*; et al.
Physical Review B, 111(21), p.214412_1 - 214412_17, 2025/06
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)We study the magnetic properties of the metallic kagome system (FeCo)Sn by a combination of muon spin relaxation (SR), magnetic susceptibility, and scanning tunneling microscopy (STM) measurements in single crystal specimens with Co concentrations 
= 0, 0.11, 0.8. In the undoped antiferromagnetic compound FeSn, we find possible signatures for a previously unidentified phase that sets in at 
~K, well beneath the Neel temperature 
~K as indicated by a peak in the relaxation rate 1/
observed in zero field (ZF) and longitudinal field (LF) SR measurements, with a corresponding anomaly in the ac and dc susceptibility, and an increase in the static width 1/
in ZF-SR measurements. No signatures of spatial symmetry breaking are found in STM down to 7~K. Related to the location and motion of muons in FeSn, we confirmed a previous report that about 40% of the implanted muons reside at a field-cancelling high symmetry site at 
~K, while an onset of thermal hopping changes the site occupancy at higher temperatures. In Fe
Co
Sn, where disorder eliminated the field-cancellation effect, all the implanted muons exhibit precession and/or relaxation in the ordered state. In Fe
Co
Sn, we find canonical spin glass behavior with freezing temperature 
~K; the ZF and LF-SR time spectra exhibit results similar to those observed in dilute alloy spin glasses CuMn and AuFe, with a critical behavior of 
at 
and 
as 
. The absence of spin dynamics at low temperatures makes a clear contrast to the spin dynamics observed by SR in many geometrically frustrated spin systems on insulating kagome, pyrochlore, and triangular lattices. The spin glass behavior of CoSn doped with dilute Fe moments is shown to originate primarily from the randomness of doped Fe moments rather than due to geometrical frustration of the underlying lattice.
野口 祐二*; 阿蘇 星侑*; 大山 研二*; 石垣 徹*; 米田 安宏; 松尾 拓紀*
Physical Review B, 111(21), p.214113_1 - 214113_13, 2025/06
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)200Kで収集した放射光X線回折データに対する最大エントロピー法(MEM)/リートベルト解析と密度汎関数理論(DFT)計算を組み合わせ、高品質なチタン酸ビスマスナトリウム(Bi
NaTiO)粉末の電子構造を解析した。その結果、Bi-O共有結合とそれに伴う強誘電性は、主にTi-3dを介したBi-6p-O3-2p軌道相互作用に起因することがわかった。
InPatel, D.*; Srivastava, P. C.*; 清水 則孝*; 宇都野 穣
Physical Review C, 111(6), p.064303_1 - 064303_13, 2025/06
被引用回数：0 パーセンタイル：0.00In同位体は陽子数50の魔法数から1つだけ少ない陽子数をもつため、陽子の一粒子エネルギーを強く反映しているとされている。これらの同位体に対し、大規模殻模型計算を行った結果、これまでは重要でないと考えられていた
軌道や
軌道の配位混合が第一励起準位を正しく得るのに大きな役割を果たすことがわかった。最近測定された磁気モーメント、四重極モーメントや、分光学的因子もよく再現されるとともに、この描像がよく成り立つことがわかった。
Sud, A.*; 山本 慧; 飯浜 賢志*; 石橋 一晃*; 深見 俊輔*; 紅林 秀和*; 水上 成美*
Physical Review Letters, 134(24), p.246704_1 - 246704_7, 2025/06
被引用回数：1 パーセンタイル：69.38(Physics, Multidisciplinary)We investigate the nonlinear coupling between acoustic (ac) and optical (op) modes in the coupled magnetization dynamics of synthetic antiferromagnets (SyAFs), utilizing current-driven resonance spectroscopy. A clear spectral splitting is evident in the ac mode when strongly excited by the radio frequency (RF) current at the driving frequency half that of the op mode resonance. The Landau-Lifshitz phenomenology aligns with the experimental observations, affirming the coupling of the RF-excited ac and op modes through three-magnon mixing. The nonlinearity enables a Rabi-like splitting in in-plane magnetized SyAF without breaking its natural symmetries. This discovery holds potential for advancing our understanding of nonlinear antiferromagnetic dynamics.
目黒 智成*; 小沢 耀弘*; 小林 浩二*; 荒木 康史; 野村 健太郎*
Physical Review Research (Internet), 7(2), p.L022065_1 - L022065_8, 2025/06
We theoretically find a topological spin-orbit torque (SOT) in the compensated ferrimagnetic Weyl semimetal TiMnAl. The topological SOT arises from all the occupied states, which is free from dissipation. However, it is negligible in metallic magnets and was not reported in Weyl semimetals. We show the enhancement of the topological SOT from the mixed Berry curvature around the Weyl points in TiMnAl. This finding provides a guiding principle for designing highly efficient SOT devices using the topological nature of ferrimagnetic Weyl semimetals.
Go, G.*; Goli, D. P.*; 江崎 蘭世; Tserkovnyak, Y.*; Kim, S. K.*
Physical Review Research (Internet), 7(2), p.L022066_1 - L022066_7, 2025/06
It remains an open question whether or not the scalar spin chirality itself can exhibit a Hall-type transport. In this work, we show that the answer is yes: The scalar spin chirality is Hall-transported in Kagome ferromagnets and antiferromagnets under an external bias, engendering a phenomenon which we dub the scalar spin chirality Nernst effect. Our findings call for the need to lift the conventional assumption that the scalar spin chirality is a static quantity in order to discover the active roles of the scalar spin chirality in transport properties.
phases in undoped and Ca-modified sodium niobates阿蘇 星侑*; 松尾 拓紀*; 米田 安宏; 森川 大輔*; 津田 健治*; 大山 研司*; 石垣 徹*; 野口 祐二*
Physical Review B, 111(17), p.174114_1 - 174114_12, 2025/05
被引用回数：1 パーセンタイル：68.15(Materials Science, Multidisciplinary)高分解能放射光X線・中性子回折、収束電子線回折、密度汎関数理論(DFT)計算を組合せた解析により、Ca修飾NaNbO
と非ドープNaNbOの結晶構造、phase転移、相安定性を調べた。その結果、Ca修飾によって反強誘電体(AFE)-相が200Kから800Kの広い温度範囲で安定化されること、NaNbOは格子膨張を伴う温度誘起等方圧によって安定化されるのに対し、Ca修飾NaNbOは格子収縮を伴う組成誘起化学圧力によって安定化されることが示された。
