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論文

Crystal structures of ReO$$_3$$ under hydrostatic pressure; A Combined neutron, X-ray, Raman, and first-principles calculation study

Efthimiopoulos, 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

https://doi.org/10.1103/PhysRevB.111.134103
 被引用回数：0

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$$_3$$の高圧力下での挙動を15GPaまで包括的に調べた。常圧$$Pm$$=3$$m$$構造は0.7GPaで空間群$$Im$$=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$$C2/c$$構造や菱面体晶$$R$$=3$$c$$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、$$Im$$=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$$^{18}$$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$$_6$$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。

論文

Magnetoferroelectric phase transition induced by latent spin-lattice coupling in the geometrically frustrated magnet $$mathrm{CuFe_{0.95}Al_{0.05}O_{2}}$$

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

https://doi.org/10.1103/PhysRevB.111.134403
 被引用回数：0

In multiferroic CuFe$$_{0.95}$$Al$$_{0.05}$$O$$_{2}$$, applying uniaxial pressure $$p$$ 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 $$p$$-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 CuFe$$_{0.95}$$Al$$_{0.05}$$O$$_{2}$$ is distorted by applied $$p$$. Although lattice distortion during the magnetic phase transition in CuFe$$_{0.95}$$Al$$_{0.05}$$O$$_{2}$$ is mitigated by the substitution of nonmagnetic Al$$^{3+}$$, the application of $$p$$ 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 $$p$$-induced ferroelectric polarization, but does not affect lattice distortion. These results indicate that $$p$$-induced ferroelectric polarization is not a consequence of the piezoelectric effect. Instead, the sinusoidal magnetic structure would contribute to the emergence of $$p$$-induced ferroelectric polarization through spin-lattice coupling.

論文

Mechanical multiplexer of nuclear spin states

中堂 博之; 横井 直人*; 松尾 衛; 針井 一哉*; 鈴木 淳*; 今井 正樹; 佐藤 正寛*; 前川 禎通*; 齊藤 英治*

Physical Review Letters, 134(13), p.130603_1 - 130603_5, 2025/04

https://doi.org/10.1103/PhysRevLett.134.130603
 被引用回数：0

A spin 1/2 is the simplest system that has been believed to support a single two-level quantum system, represented by a single resonance. We experimentally demonstrate that a spin-1/2 nucleus of $$^{19}$$F in C$$_{6}$$F$$_{6}$$ exhibits an extra resonance corresponding to the emergence of the states, by mechanically rotating a sample and a coil in nuclear magnetic resonance (NMR) measurements. On the basis of the Floquet formalism, we identify the emergence of the extra two-level state due to the temporal periodicity generated by the mechanical rotation (mechanical spin multiplexing) and derive an operator algebra analogous to the planar rotor algebra in an effective description of the system. The observed multiplexing allows a single spin 1/2 to carry more than two states and potentially enabling the processing of multiple quantum bits on a single spin.

論文

Nonreciprocal resonant surface acoustic wave absorption in Y$$_{3}$$Fe$$_{5}$$O$$_{12}$$

Ba, Y.*; 山本 慧; 他6名*

Physical Review B, 111(10), p.104401_1 - 104401_15, 2025/03

https://doi.org/10.1103/PhysRevB.111.104401
 被引用回数：0

Ferrimagnet insulator yttrium iron garnet (Y$$_{3}$$Fe$$_{5}$$O$$_{12}$$, 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.

論文

Spin-singlet ground state with spin gap in $$S_{rm eff}$$ = $$frac{1}{2}$$ antiferromagnetic tetramer compound Yb$$_2$$SiO$$_5$$

長谷 正司*; 金子 耕士; 田端 千紘; 山内 宏樹; 辻井 直人*; D$"o$nni, A.*

Physical Review B, 111(9), p.094403_1 - 094403_9, 2025/03

https://doi.org/10.1103/PhysRevB.111.094403
 被引用回数：0

We studied magnetic properties of Yb$$_2$$SiO$$_5$$ having pseudospins of $$S_{rm eff}$$ = $$frac{1}{2}$$ 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 Yb$$_2$$SiO$$_5$$ is the $$S_{rm eff}$$ = $$frac{1}{2}$$ AFM tetramer with two exchange interactions of $$J_1 = 0.74$$ and $$J_2 = 0.95$$~meV. The spin tetramer can explain the excitation energies, $$chi (T)$$, magnetic specific heat at $$T < 15$$~K, and the magnitude of the scattering vector ($$Q$$) dependence of the intensity [$$I(Q)$$] at 0.7 and 1.2 meV. The spin tetramer, however, cannot explain well $$I(Q)$$ at 1.9 meV and $$I(T)$$ of the three excitations probably due to effects of weak inter-tetramer interactions.

論文

Magnetic and quadrupole coupling emerging in NdB$$_4$$ 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

https://doi.org/10.1103/PhysRevB.111.104424
 被引用回数：0

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$$_4$$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。$$|pm frac{5}{2}rangle$$と$$|pm frac{7}{2}rangle$$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$$langle J_x rangle J_x$$、磁気$$J_x$$と四極子$$O_{zx}$$の結合、そして一軸的な結晶場により説明される。この$$f$$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$$m_perp=langle J_x rangle$$と結く誘起された2次的な秩序変数$$m_c=langle J_z rangle$$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。

論文

Spontaneous magnetic field and disorder effects in BaPtAs$$_{1-x}$$Sb$$_x$$ 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

https://doi.org/10.1103/PhysRevB.111.L100508
 被引用回数：0

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 ($$mu$$SR) results of layered pnictide BaPtAs$$_{1-x}$$Sb$$_x$$ with a honeycomb network composed of Pt and (As, Sb). We observed an increase of the zero-field $$mu$$SR rate in the superconducting (SC) state at the Sb end of $$x=1.0$$, 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 $$x=0.9$$ and 0.2, respectively, suggesting that the time-reversal symmetry-breaking SC state in $$x=1.0$$ is sensitive to disorder. The magnetic penetration depth estimated from transverse-field $$mu$$SR measurements at $$x=1.0$$ and 0.2 behaved like weak-coupling $$s$$-wave superconductivity. These seemingly incompatible zero-field and transverse-field $$mu$$SR results of BaPtAs$$_{1-x}$$Sb$$_x$$ with $$x=1.0$$ could be understood in terms of chiral $$d$$-wave superconductivity with point nodes on the three-dimensional Fermi surface.

論文

Intrinsic low-temperature magnetic properties on ultraclean UTe$$_2$$ with $$T_c$$ = 2.1 K revealed by $$^{125}$$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

https://doi.org/10.1103/PhysRevB.111.094507
 被引用回数：0

To investigate the intrinsic magnetic properties of UTe$$_2$$, we performed $$^{125}$$Te-NMR measurements on the ultra-clean single-crystalline UTe$$_2$$ with superconducting transition temperature $$T_c$$ = 2.1 K and compared the results with those of the $$T_c$$ = 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$$_2$$ 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.

論文

Production and in-medium modification of $$phi$$ mesons in proton-nucleus reactions from a transport approach

Gubler, P.; 市川 真也; Song, T.*; Bratkovskaya, E.*

Physical Review C, 111(3), p.034908_1 - 034908_12, 2025/03

https://doi.org/10.1103/PhysRevC.111.034908
 被引用回数：0

Production and in-medium modification of hidden strange $$phi$$ mesons are studied in proton-nucleus reactions: p+C, p+Cu, and p+Pb at 12 GeV/c, partially measured by the KEK E325 Collaboration via the dilepton decay mode. This work is based on the off-shell microscopic parton-hadron-string dynamics transport approach, and especially makes it possible to simulate in-medium off-shell dynamics of the $$phi$$ meson in the reactions studied. Different in-medium scenarios for the modification of the $$phi$$ meson spectral function in nuclear matter are investigated: (i) dropping pole mass, (ii) collisional broadening, and (iii) simultaneous dropping pole mass and collisional broadening. Even though the $$phi$$ meson production in p+A reactions occurs only at densities around or below normal nuclear matter density $$rho_0$$, we find visible modifications of the generated dilepton spectra for the in-medium scenarios compared to the vacuum distribution.

論文

Transverse asymmetry of individual $$gamma$$ rays in the $$^{139}$$La($$overrightarrow{n},gamma$$)$$^{140}$$La reaction

奥泉 舞桜*; Auton, C. J.*; 遠藤 駿典; 藤岡 宏之*; 広田 克也*; 猪野 隆*; 石崎 貢平*; 木村 敦; 北口 雅暁*; 古賀 淳*; et al.

Physical Review C, 111(3), p.034611_1 - 034611_6, 2025/03

https://doi.org/10.1103/PhysRevC.111.034611
 被引用回数：0

The observed enhancement of Parity Violation in the vicinity of p-wave compound nuclear resonances for a variety of medium-heavy nuclei can be understood using the sp-mixing model. The sp-mixing model predicts several neutron energy-dependent angular correlations between the spin and momentum of neutron and $$gamma$$-ray emitted from (n,$$gamma$$) reactions. In this work, the correlation term $$overrightarrow{sigma_textrm{n}}cdot(overrightarrow{k_textrm{n}}timesoverrightarrow{k_gamma})$$ in the $$^{139}$$La($$overrightarrow{n}$$,$$gamma$$)$$^{140}$$La$$^ast$$ reaction was measured precisely and a significant transverse asymmetry was found in the transition to the excited states of $$^{140}$$La.

論文

Comprehensive Bayesian machine learning approach to estimating the total nuclear capture rate of a negative muon

岩元 大樹; 新倉 潤*; 水野 るり恵*

Physical Review C, 111(3), p.034614_1 - 034614_13, 2025/03

https://doi.org/10.1103/PhysRevC.111.034614
 被引用回数：0

1$$s$$軌道上の負ミューオンは原子核に捕獲され、原子核崩壊過程を引き起こす。負ミューオンの全核捕獲率は、地球化学、宇宙核物理学、半導体デバイス開発などの分野できわめて重要であるが、現在の物理理論モデルによる正確な予測は依然として困難である。本研究では、ベイズ統計の枠組みで物理理論の情報と実験データを統合し、負ミューオンの全核捕獲率を推定する包括的な機械学習(ML)モデルを開発することを目的とした。本研究では、ガウス過程回帰に基づくMLモデルを採用し、不確かさが評価された実験データを学習データとして用いた。このモデルは事前情報としてGoulard-Primakoffの式を取り入れ、特にデータが乏しい領域での推定を可能にするために、転移学習の方法を適用した。開発したMLモデルは、精度と包括性の両方において物理理論モデルを上回ることが示され、モデル性能をさらに向上させるための重要な実験が特定された。本研究で生成された推定値は、ミューオン核データに組み込まれ、様々な研究分野に応用される予定である。

論文

Physical properties of intergrowth compound Eu$$_{2}$$CuZn$$_{2}$$P$$_{3}$$

May, A. F.*; 田端 千紘; Okamoto, Satoshi*; Ortiz, B. R.*; Christianson, A. D.*; Yan, J.*; 金子 耕士; McGuire, M. A.*

Physical Review Materials (Internet), 9(2), p.024406_1 - 024406_13, 2025/02

https://doi.org/10.1103/PhysRevMaterials.9.024406
 被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)

The physical properties of single crystalline Eu$$_{2}$$CuZn$$_{2}$$P$$_{3}$$ were inspected via thermodynamic, transport, and neutron diffraction measurements. Eu$$_{2}$$CuZn$$_{2}$$P$$_{3}$$ is composed of EuCuP and EuZn$$_{2}$$P$$_{2}$$ motifs stacked in a one-to-one ratio. The magnetic response of Eu$$_{2}$$CuZn$$_{2}$$P$$_{3}$$ is similar to that of EuZn$$_{2}$$P$$_{2}$$ in its A-type antiferromagnetic (semiconducting) form.

論文

Multiple metamagnetic transitions in the helical antiferromagnet CeVGe$$_{3}$$

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

https://doi.org/10.1103/PhysRevB.111.035103
 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$$_{3}$$. This compound exhibits Kondo lattice coherence and helical antiferromagnetic (AFM) ordering at ambient pressure, similar to the well-studied CeRhIn$$_{5}$$. Our measurements reveal that CeVGe$$_{3}$$ 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$$_{5}$$. Furthermore, angle-dependent magnetoresistance measurements reveal that all transitions in CeVGe$$_{3}$$ 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.

論文

Theory of the spin Seebeck effect influenced by crystal-field excitations in Tb$$_3$$Fe$$_5$$O$$_{12}$$

森 道康; Tomasello, B.*; Ziman, T.*

Physical Review B, 111(1), p.014407_1 - 014407_12, 2025/01

https://doi.org/10.1103/PhysRevB.111.014407
 被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)

The spin Seebeck effect (SSE) is a phenomenon of thermoelectric generation that occurs within a device consisting of a bilayer of a metal and a ferromagnet. When Tb$$_3$$Fe$$_5$$O$$_{12}$$ (TbIG) is substituted for the ferromagnet, the effect goes to zero at low temperatures, yet it increases to positive values with the application of a magnetic field. This is opposite to the expectation that the SSE should be suppressed by a magnetic field due to the increase in ${the}$ magnon gap. In this paper, the crystal-field excitations (CFE) in TbIG are calculated within a mean field theory exploiting the parameters of Terbium Gallium Garnet Tb$$_3$$Fe$$_5$$O$$_{12}$$ (TGG) from the neutron-scattering experimental literature. Like TGG, the primitive cell of TbIG hosts twelve Tb sites with six inequivalent magnetic sublattices, but due to the net $$[111]$$-molecular field from the tetrahedral and octahedral Fe ions, these can be classified into two distinct groups, the $$mathbf{C}$$ and the $$mathbf{C'}$$ sites, which account for the "double umbrella" magnetic structure. We show that when an external magnetic field is applied along the [111] direction of the crystal, the lowest CFE of the $$mathbf{C}$$ sublattices decreases. As a consequence of the magnetic field dependence of the lowest CFE, we find that at low temperatures the SSE in TbIG can result enhanced by an applied magnetic field.

論文

Observation of nonreciprocal diffraction of surface acoustic wave

新居 陽一*; 山本 慧; 菅野 将誠*; 前川 禎通*; 小野瀬 佳文*

Physical Review Letters, 134(2), p.027001_1 - 027001_5, 2025/01

https://doi.org/10.1103/PhysRevLett.134.027001
 被引用回数：1 パーセンタイル：91.89(Physics, Multidisciplinary)

While the rectification phenomenon caused by the simultaneous breaking of time reversal and spatial inversion symmetries has been extended to a wide range of (quasi)particles and waves, the nonreciprocal diffraction, which is the imbalance of upward and downward deflections, was previously observed only for photons and remained to be extended to other (quasi)particles. Here, we present evidence of the nonreciprocal diffraction of surface acoustic wave (SAW) utilizing a magnetoelastic grating on a SAW device. Asymmetric diffraction intensities were observed when the ferromagnetic resonance was acoustically excited. Based on a theoretical model, we ascribe the microscopic origin of this phenomenon to the resonant scattering involving ferromagnetic resonance excitations. The novel property may pave an avenue to further development of SAW devices for various purposes including microwave communications and quantum engineering applications.

論文

Possible field-induced quantum state in a rhombic lattice antiferromagnet KCoPO$$_{4}$$$$cdot$$H$$_{2}$$O

藤原 理賀; 萩原 雅人; 幸田 章宏*; 中村 惇平*; 松尾 晶*; 金道 浩一*; 石角 元志*

Physical Review Materials (Internet), 9(1), p.014406_1 - 014406_9, 2025/01

https://doi.org/10.1103/PhysRevMaterials.9.014406
 被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)

We reported the magnetic behavior of a rhombic lattice quantum antiferromagnet KCoPO$$_{4}$$$$cdot$$H$$_{2}$$O. The rhombic lattice model is equivalent to a model of a square lattice with two different diagonal components, and competing exchange interactions potentially produce exotic quantum states. This compound is well characterized by the $$J$$$$_{rm{eff}}$$ = 1/2 state. The magnetic structure of KCoPO$$_{4}$$$$cdot$$H$$_{2}$$O is identified as an incommensurate helical structure, characterized by a magnetic modulation propagation vector $$bold{k}$$ = (0.1747(1) 0 0) with an in-plane moment rotating along the $$a$$ axis. Moreover, a magnetic field-induced phase transition is observed at approximately 1 T. The application of a magnetic field suppresses spin ordering and enhance spin fluctuations. Our experimental results suggest the presence of a quantum phase in the magnetic phase diagram of the spin-1/2 Heisenberg rhombic lattice antiferromagnet with easy-plane anisotropy.

論文

Surface structure of the 3$$times$$3-Si phase on Al(111), studied by the multiple usages of positron diffraction and core-level photoemission spectroscopy

佐藤 祐輔*; 深谷 有喜; 他14名*

Physical Review Materials (Internet), 9(1), p.014002_1 - 014002_11, 2025/01

https://doi.org/10.1103/PhysRevMaterials.9.014002
 被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)

本研究では、陽電子回折と内殻光電子分光の複合利用により、Al(111)3$$times$$3-Si表面の構造を明らかにした。ロッキング曲線の解析では、3$$times$$3-Si相が平坦なハニカム構造から構成されること、また、第一原理計算に基づくSi内殻スペクトルの解析では、単位胞内のSi原子の一つがAl原子と置換されていることがわかった。すなわち、3$$times$$3-Si相の表面超構造はAl原子を内包したSi二次元層である。

論文

Magnetic excitations in the noncentrosymmetric magnet Sr$$_{2}$$MnSi$$_{2}$$O$$_{7}$$

川又 雅広*; Pang, X.*; 村川 寛*; 河村 聖子; 中島 健次; 増田 英敏*; 藤田 全基*; 花咲 徳亮*; 小野瀬 佳文*; 南部 雄亮*

Physical Review Materials (Internet), 9(1), p.014407_1 - 014407_6, 2025/01

https://doi.org/10.1103/PhysRevMaterials.9.014407
 被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)

Magnetic excitations in the noncentrosymmetric magnet Sr$$_{2}$$MnSi$$_{2}$$O$$_{7}$$ were investigated through inelastic neutron scattering measurements. Major magnetic excitations are limited up to the energy transfer of 0.5 meV, and two magnon branches under zero magnetic field were well explained in the framework of linear spinwave theory. The magnitudes of the square-lattice in-plane and interplane nearest-neighbor interactions, spin anisotropy term, and the Dzyaloshinskii-Moriya interaction are, respectively, estimated to be J$$_{1}$$ = 45.54(5) $$mu$$eV, J$$_{2}$$ = 0.52(1) $$mu$$eV, = 4.98(11) $$mu$$eV, D$$_{xy}$$ = 0.02(9) $$mu$$eV, and D$$_{z}$$ = 4.10(1) $$mu$$eV, and calculations using these parameters reproduce experimental data quite well. Sr$$_{2}$$MnSi$$_{2}$$O$$_{7}$$ appears to have the smallest energy scale among the melilite-type compounds, and the small J$$_{2}$$/J$$_{1}$$ = 0.0114(2) indicates the strong two dimensionality.

論文

Interfacial Dzyaloshinskii-Moriya interaction in nonmagnetic/noncollinear-antiferromagnetic bilayers

山根 結太*; 荒木 康史; 深見 俊輔*

Physical Review B, 111(14), p.144412_1 - 144412_9, 2025/00

https://doi.org/10.1103/PhysRevB.111.144412
 被引用回数：0

We study the Dzyaloshinskii-Moriya interaction (DMI) appearing at the interface of a nonmagnetic/noncollinear-antiferromagnetic bilayer. The DMI is an antisymmetric exchange interaction between neighboring magnetic spins, arising in the absence of an inversion center between the spins, the explicit expression of which is dictated by system symmetry. We formulate the interfacial DMI for different crystalline orientations of the noncollinear antiferromagnet with a stacked-kagome lattice structure. From this formulation, we show that, when the kagome planes are perpendicular to the sample film plane, the DMI serves as a uniaxial magnetic anisotropy for the antiferromagnetic order parameter. Our findings reveal an important physical manifestation of a DMI, shedding light on microscopic mechanisms of the magnetic anisotropy in noncollinear antiferromagnets.

論文

First measurement of missing energy due to nuclear effects in monoenergetic neutrino charged-current interactions

Marzec, E.*; 百々 拓; 羽賀 勝洋; 原田 正英; 長谷川 勝一; 春日井 好己; 木下 秀孝; 増田 志歩; 明午 伸一郎; 酒井 健二; et al.

Physical Review Letters, 134, p.081801_1 - 081801_9, 2025/00

https://doi.org/10.1103/PhysRevLett.134.081801

We present the first measurement of the missing energy due to nuclear effects in monoenergetic, muon neutrino charged-current interactions on carbon, originating from $$K^+ to mu^+ nu_{mu}$$ decay at rest ($$E_{nu_{mu}} = 235.5 MeV$$), performed with the J-PARC Sterile Neutrino Search at the J-PARC Spallation Neutron Source liquid scintillator based experiment. Toward characterizing the neutrino interaction, ostensibly $$nu_{mu}n to mu^- p$$ or $$nu_{mu}$$ $$^{12}$$C $$to$$ $$mu^-$$ $$^{12}$$N, we define the missing energy as the energy transferred to the nucleus ($$omega$$) minus the kinetic energy of the outgoing proton(s), $$E_m equiv omega - Sigma T_p$$, and relate this to visible energy in the detector, $$E_m = E_{nu_{mu}} (235.5 MeV) - m_{mu}(105.7 MeV) + [m_n - m_p(1.3 MeV)] - E_{vis}$$. The missing energy, which is naively expected to be zero in the absence of nuclear effects (e.g., nucleon separation energy, Fermi momenta, and final-state interactions), is uniquely sensitive to many aspects of the interaction, and has previously been inaccessible with neutrinos. The shape-only, differential cross section measurement reported, based on a $$(77pm 3%)$$ pure double-coincidence kaon decay-at-rest signal (621 total events), provides detailed insight into neutrino-nucleus interactions, allowing even the nuclear orbital shell of the struck nucleon to be inferred. The measurement provides an important benchmark for models and event generators at hundreds of MeV neutrino energies, characterized by the difficult-to-model transition region between neutrino-nucleus and neutrino-nucleon scattering, and relevant for applications in nuclear physics, neutrino oscillation measurements, and Type-II supernova studies.

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