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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.
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.
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.
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.
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。
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.
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。
Labib, F.*; 杉本 貴則*; 高倉 洋礼*; 石川 明日香*; 田村 隆治*
Physical Review B, 111(17), p.174409_1 - 174409_9, 2025/05
被引用回数：3 パーセンタイル：92.31(Materials Science, Multidisciplinary)The structural and physical properties of two single-grain Au-Al-Gd 1/1 approximant crystals (ACs) with analyzed compositions Au
Al
Gd
and Au
Al
Gd
were thoroughly investigated. The two variants are isostructural, undergoing sharp antiferromagnetic (AFM) transitions at 
= 9.6 K and = 8.3 K, respectively. Specific-heat measurements in both samples evidenced sharp jump at , associated with the AFM transition, accompanied by broad Schottky-type anomalies at lower temperatures. Strikingly, the two 1/1 ACs exhibited markedly different responses to applied magnetic fields: one displayed a pronounced metamagnetic anomaly while the other did not. In this regard, variational calculations with adiabatic transformation of the magnetic field in realistic structural models identified the existence of two possible AFM phases: the cuboc phase with a metamagnetic anomaly and the cluster Neel phase without it, thereby clearly revealing the possible magnetic structures of the present AFM variants.
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。
山 正樹*; 松尾 衛; 加藤 岳生*
Physical Review B, 111(14), p.144416_1 - 144416_20, 2025/04
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)We theoretically study Rashba-Edelstein magnetoresistance (REMR) in a two-dimensional electron gas (2DEG) system with Rashba and Dresselhaus spin-orbit interactions.
玉造 博夢; 内原 猛*; 満田 節生*; 石井 祐太*; 中尾 裕則*; 竹端 寛治*; 今中 康貴*
Physical Review B, 111(13), p.134403_1 - 134403_9, 2025/04
被引用回数：1 パーセンタイル：68.15(Materials Science, Multidisciplinary)In multiferroic CuFe
Al
O, applying uniaxial pressure 
generates a magnetoferroelectric phase distinct from the well-studied spin-driven ferroelectric phase associated with helical magnetic ordering in this system. Using a four-circle neutron diffractometer, the magnetic structure of the -induced magnetoferroelectric phase is determined as the collinear sinusoidal type, which itself does not break the inversion symmetry in this system. Additionally, synchrotron radiation X-ray diffraction experiments are conducted to investigate how the triangular lattice in CuFeAlO is distorted by applied . Although lattice distortion during the magnetic phase transition in CuFeAlO is mitigated by the substitution of nonmagnetic Al, the application of along the conjugate direction revives the "latent" spin-lattice coupling, causing the triangular lattice to distort during magnetic phase transition. The application of a magnetic filed considerably reduces -induced ferroelectric polarization, but does not affect lattice distortion. These results indicate that -induced ferroelectric polarization is not a consequence of the piezoelectric effect. Instead, the sinusoidal magnetic structure would contribute to the emergence of -induced ferroelectric polarization through spin-lattice coupling.
under hydrostatic pressure; A Combined neutron, X-ray, Raman, and first-principles calculation studyEfthimiopoulos, I.*; Klotz, S.*; Kunc, K.*; Baptiste, B.*; Chauvigne, P.*; 服部 高典
Physical Review B, 111(13), p.134103_1 - 134103_13, 2025/04
被引用回数：1 パーセンタイル：68.15(Materials Science, Multidisciplinary)X線回折、中性子回折、ラマン散乱、第一原理計算を用いて、ReOの高圧力下での挙動を15GPaまで包括的に調べた。常圧
=3
構造は0.7GPaで空間群
=3の立方晶相に連続的に相転移し、その後少なくとも15GPaまで安定であることがわかった。過去この圧力領域で報告されていた単斜晶
構造や菱面体晶=3
構造への転移は、試料に高輝度放射光X線を照射したことによる試料の劣化によるものであり、人工的なものであることが分かった。また今回、=3相の構造の圧力依存性と正確な状態方程式および天然試料と同位体濃縮
O試料のラマン散乱データを示した。このデータから、リジッドなReO八面体が圧力とともに回転することによって、相転移および高密度化が起こることが分かった。
= 
antiferromagnetic tetramer compound YbSiO
長谷 正司*; 金子 耕士; 田端 千紘; 山内 宏樹; 辻井 直人*; D
nni, A.*
Physical Review B, 111(9), p.094403_1 - 094403_9, 2025/03
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)We studied magnetic properties of YbSiO having pseudospins of = using magnetization, specific heat, and inelastic neutron scattering (INS) measurements. We observed cluster-like excitations in the INS measurements. We determined that the spin system in YbSiO is the = AFM tetramer with two exchange interactions of 
and 
~meV. The spin tetramer can explain the excitation energies, 
, magnetic specific heat at 
~K, and the magnitude of the scattering vector (
) dependence of the intensity [
] at 0.7 and 1.2 meV. The spin tetramer, however, cannot explain well at 1.9 meV and 
of the three excitations probably due to effects of weak inter-tetramer interactions.
Sb with a honeycomb network足立 匡*; Ogawa, Taiki*; 小宮山 陽太*; 須村 拓也*; Saito-Tsuboi, Yuki*; Takeuchi, Takaaki*; Mano, Kohei*; Manabe, Kaoru*; 川端 幸樹*; 今津 毅士*; et al.
Physical Review B, 111(10), p.L100508_1 - L100508_6, 2025/03
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)Chiral superconductivity exhibits the formation of novel electron pairs that breaks the time-reversal symmetry and has been actively studied in various quantum materials in recent years. However, despite its potential to provide definitive information, effects of disorder in the crystal structure on the chiral superconductivity has not yet been clarified, and therefore the investigation using a solid-solution system is desirable. We report muon-spin-relaxation (SR) results of layered pnictide BaPtAsSb with a honeycomb network composed of Pt and (As, Sb). We observed an increase of the zero-field SR rate in the superconducting (SC) state at the Sb end of 
, suggesting the occurrence of a spontaneous magnetic field due to the time-reversal symmetry breaking in the SC state. On the other hand, a spontaneous magnetic field was almost and completely suppressed for the As-Sb mixed samples of 
and 0.2, respectively, suggesting that the time-reversal symmetry-breaking SC state in is sensitive to disorder. The magnetic penetration depth estimated from transverse-field SR measurements at and 0.2 behaved like weak-coupling 
-wave superconductivity. These seemingly incompatible zero-field and transverse-field SR results of BaPtAsSb with could be understood in terms of chiral 
-wave superconductivity with point nodes on the three-dimensional Fermi surface.
with 
= 2.1 K revealed by 
Te NMR松村 拓輝*; 徳永 陽; 酒井 宏典; 神戸 振作; 他13名*
Physical Review B, 111(9), p.094507_1 - 094507_9, 2025/03
被引用回数：2 パーセンタイル：85.69(Materials Science, Multidisciplinary)To investigate the intrinsic magnetic properties of UTe, we performed Te-NMR measurements on the ultra-clean single-crystalline UTe with superconducting transition temperature = 2.1 K and compared the results with those of the = 1.6 K sample. The broadening of the linewidth of the NMR spectrum in the a-axis magnetic field and the low-temperature magnetic fluctuations observed in the 1.6 K sample are suppressed in the ultra-clean sample, indicating that such magnetic properties originate from a tiny amount of U deficiency. The present results suggest that the magnetic properties in UTe are sensitive to the U deficiency. We also observed a peculiar angular dependence of the NMR quantities due to large magnetic anisotropy with the a-axis as the magnetic easy axis.
with geometrically frustrated orthogonal antiferromagnetic dimer目時 直人; 山内 宏樹; 萩原 雅人; 綿貫 竜太*; 河村 聖子; 古府 麻衣子*; 中島 健次; 松田 雅昌*
Physical Review B, 111(10), p.104424_1 - 104424_9, 2025/03
被引用回数：1 パーセンタイル：68.15(Materials Science, Multidisciplinary)フラストレートしたシャストリ・サザランド格子を有するNdBの磁気転移を理解する目的で中性子非弾性散乱実験を行った。
と
による準四重項状態が磁気秩序相で4つに分裂する。スペクトルは磁気相互作用
、磁気
と四極子
の結合、そして一軸的な結晶場により説明される。この
電子状態により、主たる秩序変数である面内磁気モーメント
と結く誘起された2次的な秩序変数
を説明することができた。幾何学的フラストレーションによってハイゼンベルグ相互作用が打ち消し合う状況で、磁気と四極子の結合が本質的な役割をすることが明らかになった。
Fe
O
Ba, Y.*; 山本 慧; 他6名*
Physical Review B, 111(10), p.104401_1 - 104401_15, 2025/03
被引用回数：1 パーセンタイル：68.15(Materials Science, Multidisciplinary)Ferrimagnet insulator yttrium iron garnet (YFeO, YIG) attracts much interest in magnonics and microwave applications due to its relatively low magnetic damping and long magnon relaxation time. The magnetoelastic interaction between YIG magnetization and surface acoustic waves (SAWs) has been the basis in the development of acoustic-surface-wave isolators. However, the investigation of SAW-driven magnetic resonance in YIG is limited by the low compatibility of YIG and SAW devices. In this work, we demonstrate nonreciprocal resonant SAW absorption in an on-chip YIG-SAW device integrated by the focused ion beam technique. We observed two distinct SAW absorption signals attributed to the perpendicular standing spin waves (PSSW). Furthermore, the large observed nonreciprocity is compared to theoretical predictions incorporating the influence of asymmetric surface conditions on PSSW mode profiles and nonreciprocal magnon-SAW coupling. The strongly nonreciprocal SAW attenuation in YIG offers a promising opportunity for highly efficient rf signal processing technologies.
船戸 匠*; 木下 俊一郎*; 棚橋 典大*; 中村 真*; 松尾 衛
Physical Review B, 111(6), p.L060403_1 - L060403_7, 2025/02
被引用回数：1 パーセンタイル：68.15(Materials Science, Multidisciplinary)We study nonequilibrium spin dynamics in differentially rotating systems, deriving an effective Hamiltonian for conduction electrons in the comoving frame. In contrast to conventional spin current generation mechanisms that require vorticity, our theory describes spins and spin currents arising from differentially rotating systems regardless of vorticity. We demonstrate the generation of spin currents in differentially rotating systems, such as liquid metals with Taylor-Couette flow. Our alternative mechanism will be important in the development of nanomechanical spin devices.
Jin, H.*; Choi, E. S.*; Wu, H.-C.*; Curro, N. J.*; 那波 和宏*; 佐藤 卓*; 鬼柳 亮嗣; 大原 高志; Klavins, P.*; Taufour, V.*
Physical Review B, 111(3), p.035103_1 - 035103_7, 2025/01
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)We report on neutron diffraction, magnetoresistance, magnetization and magnetic torque measurements under high magnetic field in the helical antiferromagnet CeVGe. This compound exhibits Kondo lattice coherence and helical antiferromagnetic (AFM) ordering at ambient pressure, similar to the well-studied CeRhIn. Our measurements reveal that CeVGe undergoes a magnetic transition from an incommensurate (ICM) AFM state to an up-up-down-down commensurate (CM) AFM structure, followed by a transition to a novel phase at higher fields. A quantum phase transition occurs around 21.3 T. This rich magnetic field phase diagram closely resembles that of CeRhIn. Furthermore, angle-dependent magnetoresistance measurements reveal that all transitions in CeVGe occur from the field component along the ab plane. These findings highlight the intricate interplay among exchange interactions, crystal field effects, ground state properties, and crystalline symmetries.
