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orbital system on a simple cubic lattice久保 勝規
Journal of the Physical Society of Japan, 94(5), p.054703_1 - 054703_7, 2025/05
A tight-binding model for orbitals on a simple cubic lattice with finite thickness is investigated. The hopping integrals for nearest-neighboring sites are considered. We examine the electronic band structures for systems with (001), (110), and (111) surfaces. Electronic states well localized around the surfaces are found for the (110) and (111) surfaces. In particular, the surface state is flat and extends in the entire Brillouin zone for the (111) surface, provided the bulk band projected onto the surface Brillouin zone is gapped. We also find that these surface states possess octupole moments in both the (110) and (111) surface cases.
山内 宏樹; 目時 直人; 綿貫 竜太*; Hong, T.*; Fernandez-Baca, J. A.*; 萩原 雅人; 益田 隆嗣*; 吉沢 英樹*; 伊藤 晋一*
Journal of the Physical Society of Japan, 94(5), p.054705_1 - 054705_8, 2025/04
The 
-electron states of NdB were determined by observing crystalline electric field (CEF) excitations with inelastic neutron scattering experiments. Our analysis yields CEF excitation energies of 2.8, 12.4, 17.2, and 25.4 meV. The -electron states are simply described by one of 
-multiplets 
with negligibly small mixing. The ground state is the pseudo-quartet consist of the ground doublet dominated by 
and the first excited doublet dominated by 
at 2.8 meV, which is consistent with magnetic specific heat and entropy reported in earlier study. The simple -electron states in NdB are the consequence of the strong uniaxial and in-plane isotropic CEF potential due to the local structure of Nd
ions with point symmetry 
.
松谷 悠佑; 吉井 勇治*; 楠本 多聞*; 小川 達彦; 大西 世紀*; 平田 悠歩; 佐藤 達彦; 甲斐 健師
Physical Chemistry Chemical Physics, 27(14), p.6887 - 6898, 2025/04
被引用回数：0 パーセンタイル：0.00(Chemistry, Physical)水の放射線分解により生成されるラジカルは、DNA損傷誘発、染色体異常、発がんなど、放射線による生物影響の評価において重要な役割を果たす。粒子および重イオン輸送コードシステム(PHITS)では、あらゆる荷電粒子について水中の原子相互作用を推定できる飛跡構造解析モードと、ラジカルをシミュレート可能な電子線専用の化学コード(PHITS-Chem)が先行研究にて開発された。本研究では、あらゆるイオンビームに適用可能なPHITS-Chemコードを開発すると同時に、化学種間の反応をより効率的に検出する空間分割法や化学種の4次元可視化機能を整備した。更新されたPHITS-Chemコードは、文献にて報告される陽子線、
粒子線、炭素イオン線のG値と比較することにより検証され、PHITSオリジナル3次元描画ソフトPHIG-3Dによりラジカルの拡散動態を直感的に評価することに成功した。また、空間分割法の導入により、計算精度を維持しながら計算時間を大幅に短縮(約28倍高速化)することにも成功した。開発したPHITS-Chemコードは、粒子線治療においてラジカルにより誘発される生物効果の正確かつ直感的な理解に貢献することが期待される。
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：0In 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：0X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。
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
被引用回数：0A 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 
F in C
F 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.
Rajeev, H. S.*; Hu, X.*; Chen, W.-L.*; Zhang, D.*; Chen, T.*; 古府 麻衣子*; 梶本 亮一; 中村 充孝; Chen, A. Z.*; Johnson, G. C.*; et al.
Journal of the Physical Society of Japan, 94(3), p.034602_1 - 034602_14, 2025/03
被引用回数：0Two-dimensional hybrid organic-inorganic perovskites (HOIPs) have emerged as promising materials for light-emitting diode applications. In this study, by using time-of-flight neutron spectroscopy we identified and quantitatively separated the lattice vibrational and molecular rotational dynamics of two perovskites, butylammonium lead iodide (BA)PbI
and phenethyl-ammonium lead iodide (PEA)PbI. By examining the corresponding temperature dependence, we found that the lattice vibrations, as evidenced by neutron spectra, are consistent with the lattice dynamics obtained from Raman scattering. We revealed that the rotational dynamics of organic molecules in these materials tend to suppress their photoluminescence quantum yield (PLQY) while the vibrational dynamics did not show predominant correlations with the same. Additionally, we observed photoluminescence emission peak splitting for both systems, which becomes prominent above certain critical temperatures where the suppression of PLQY begins. This study suggests that the rotational motions of polarized molecules may lead to a reduction in exciton binding energy or the breaking of degeneracy in exciton binding energy levels, enhancing non-radiative recombination rates, and consequently reducing photoluminescence yield. These findings offer a deeper understanding of fundamental interactions in 2D HOIPs and could guide the design of more efficient light-emitting materials for advanced technological applications.
= 
antiferromagnetic tetramer compound Yb
SiO
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：0We 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.
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：0Ferrimagnet 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.
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：0To 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：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。
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：0Chiral 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.
mesons in proton-nucleus reactions from a transport approachGubler, P.; 市川 真也; Song, T.*; Bratkovskaya, E.*
Physical Review C, 111(3), p.034908_1 - 034908_12, 2025/03
被引用回数：0Production and in-medium modification of hidden strange 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 meson in the reactions studied. Different in-medium scenarios for the modification of the 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 meson production in p+A reactions occurs only at densities around or below normal nuclear matter density 
, we find visible modifications of the generated dilepton spectra for the in-medium scenarios compared to the vacuum distribution.
岩元 大樹; 新倉 潤*; 水野 るり恵*
Physical Review C, 111(3), p.034614_1 - 034614_13, 2025/03
被引用回数：01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。
rays in the 
La(
)
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
被引用回数：0The 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 -ray emitted from (n,) reactions. In this work, the correlation term 
in the La(
,)La
reaction was measured precisely and a significant transverse asymmetry was found in the transition to the excited states of La.
井上 倫太郎*; 小田 隆; 中川 洋; 富永 大輝*; 池上 貴久*; 小沼 剛*; 岩瀬 裕希*; 川北 至信; 佐藤 衛*; 杉山 正明*
Biophysical Journal, 124(3), p.540 - 548, 2025/02
被引用回数：0 パーセンタイル：0.00(Biophysics)Intrinsically disordered proteins (IDPs) show structural changes stimulated by changes in external conditions. This study aims to reveal the temperature dependence of the structure and the dynamics of the intrinsically disordered region of the helicase-associated endonuclease for fork-structured DNA, one of the typical IDPs, using an integrative approach. Small-angle X-ray scattering (SAXS) and circular dichroism (CD) studies revealed that the radius of gyration and ellipticity at 222 nm remained constant up to 313-323 K, followed by a decline above this temperature range. NMR studies revealed the absence of a promotion of the -helix. As a result, SAXS, CD, and NMR data strongly suggest that these temperature-dependent structural changes were primarily due to a reduction in the content of the polyproline II (PPII) helix. Moreover, quasielastic neutron scattering studies revealed a slight change in the activation energy in a similar temperature range. Considering the concept of glass transition, it is posited that dynamical cooperativity between the PPII helix and water may play a significant role in these structural changes. The findings suggest that internal dynamics are crucial for regulating the structure of IDPs, highlighting the importance of considering dynamical cooperativity in future studies of protein behavior under varying temperature conditions.
CuZnPMay, 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
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)The physical properties of single crystalline EuCuZnP were inspected via thermodynamic, transport, and neutron diffraction measurements. EuCuZnP is composed of EuCuP and EuZnP motifs stacked in a one-to-one ratio. The magnetic response of EuCuZnP is similar to that of EuZnP in its A-type antiferromagnetic (semiconducting) form.
前田 瑞穂*; 松田 達磨*; 芳賀 芳範; 白崎 謙次*; 木村 憲彰*
Journal of the Physical Society of Japan, 94(2), p.024707_1 - 024707_6, 2025/01
被引用回数：0 パーセンタイル：0.00(Physics, Multidisciplinary)We investigate the pressure dependence of the magnetoresistivity and Hall resistivity for an itinerant-electron metamagnet UCoAl. The first-order metamagnetic transition point varies as a function of hydrostatic pressure and terminates at the critical pressure 2.0 GPa. The electronic system, however, does not show criticality at this pressure but extends to higher pressures, unlike the usual quantum critical behavior.
Che, G.*; Fei, Y.*; Tang, X.*; Zhao, Z.*; 服部 高典; 阿部 淳*; Wang, X.*; Ju, J.*; Dong, X.*; Wang, Y.*; et al.
Physical Chemistry Chemical Physics, 27(2), p.1112 - 1118, 2025/01
被引用回数：2 パーセンタイル：47.21(Chemistry, Physical)芳香族分子の圧力誘起重合(PIP)は、様々な炭素系材料を合成するための効果的な方法として浮上してきた。目的とする構造や機能を得るためには、適切な官能基化された分子前駆体の選択が極めて重要である。本研究では、1,4-ジフルオロベンゼン(1,4-DFB)をPIPの構成要素として選択した。1,4-DFBをその場高圧で調べた結果、約12.0GPaで相転移が起こり、18.7GPaで不可逆的な化学反応が起こることがわかった。生成物の構造解析と反応のカイネティクスから、直線的な成長を伴う擬六方晶積層フッ素ダイヤモンドナノスレッドの形成が明らかになった。高圧下のベンゼンの結晶構造と比較して、1,4-DFBは[001]軸に沿って高い圧縮を示す。この異方的な圧縮は、[01
]軸に沿ったより強いH
相互作用と、[100]軸と[010]軸に沿った潜在的な圧縮阻害H
F相互作用に起因し、[01]軸に沿った可能な反応経路を促進する。この研究は、分子スタッキングを調節し、反応経路に影響を与える官能基化の重要な役割を強調している。
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.
