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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：0.00(Materials Science, Multidisciplinary)The 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.
Bi
Park, P.*; Ortiz, B. R.*; Spargue, M.*; Sakuya, A. P.*; Chen, S. A.*; Frontzek, M. D.*; Tian, W.*; Sibille, R.*; Mazzone, D. G.*; 田端 千紘; et al.
Nature Communications (Internet), 16, p.4384_1 - 4384_9, 2025/05
被引用回数：14 パーセンタイル：97.77(Multidisciplinary Sciences)Kagome metals with van Hove singularities (VHSs) near the Fermi level can host intriguing quantum phenomena, including chiral loop currents, electronic nematicity, and unconventional superconductivity. However, unconventional magnetic states driven by VHSs, such as spin-density waves (SDWs), have yet to be observed experimentally in kagome metals. Here, we present a comprehensive investigation of the magnetic and electronic structure of the layered kagome metal CeTiBi, where the Ti kagome electronic structure interacts with a magnetic sublattice of Ce 
= 1/2 moments. Our findings establish the rare-earth Kagome metals LnTi3Bi4 as a model platform where characteristic electronic structure of the kagome lattice plays a pivotal role in magnetic order.
CuZnP
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
被引用回数：7 パーセンタイル：84.19(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.
-Orbital component in the Borromean nucleus 
BYang, Z. H.*; 久保田 悠樹*; Corsi, A.*; 吉田 数貴; Sun, X.-X.*; Li, J. G.*; 木村 真明*; Michel, N.*; 緒方 一介*; Yuan, C. X.*; et al.
Physical Review Letters, 126(8), p.082501_1 - 082501_8, 2021/02
被引用回数：89 パーセンタイル：97.14(Physics, Multidisciplinary)ボロミアン核であり中性子ハロー構造が期待されるBに対する(
,
)反応実験を行った。断面積の運動量分布を分析することで、
と
軌道の分光学的因子を決定した。驚くべきことに、の分光学的因子は9(2)%と小さいことが明らかになった。この結果は、連続状態を含むdeformed relativistic Hartree-Bogoliubov理論によってよく説明された。本研究の結果によると、現在知られているハロー構造を持つとされる原子核の中でBはおよび軌道の成分が最も小さく、または軌道成分が支配的であることが必ずしもハロー構造の前提条件ではない可能性を示唆している。
金子 耕士; 田端 千紘*; 竹内 徹也*; Frontzek, M. D.*; 松田 雅昌*; 大石 一城*; 伊藤 孝; 宗像 孝司*; 鬼柳 亮嗣; 垣花 将司*; et al.
no journal, ,
Magnetic skyrmion, particle-like topologically non-trivial spin textures, attracts surge of interests from both fundamental and application points of view. Since the first discovery in MnSi crystallizing in the cubic space group 
, intensive research on magnetic skyrmions has conducted for materials particularly in this space group. This leads to findings of new class of materials, whereas magnetic ions were mostly limited to d electron systems. Recently, it turned out that f-electron compounds can host magnetic skyrmion lattice as well. The magnetic skyrmions in f-electron compounds possess contrasting characteristics, such as short periodicity and strong anisotropy. Among recent discoveries, cubic chiral compound EuPtSi provides ideal opportunities to compare with d-electron systems as it crystallizes in the same space group as MnSi, namely . We will present our neutron and X-ray scattering studies to characterize magnetic skyrmion lattice in this compound.
金子 耕士; 田端 千紘*; 大石 一城*; 伊藤 孝; 中尾 裕則*; Frontzek, M. D.*; 松田 雅昌*; 宗像 孝司*; 中尾 朗子*; 大原 高志; et al.
no journal, ,
MnSiと同じ空間群に属する立方晶化合物EuPtSiでは、有限磁場・温度領域でのみ安定化する特徴的な磁場誘起秩序相であるA相が現れ、輸送特性, 中性子, X線回折から、磁気スキルミオン格子が実現していることが確認された。MnSiの磁気スキルミオン相と比べ、EuPtSi固有の特徴の一つは、強い異方性をもつことである。この点について、磁場中中性子散乱で調べた微視的な構造変化を報告する。
-electron magnet EuPtSi金子 耕士; 田端 千紘*; 竹内 徹也*; Frontzek, M. D.*; 松田 雅昌*; 大石 一城*; 伊藤 孝; 宗像 孝司*; 鬼柳 亮嗣; 垣花 将司*; et al.
no journal, ,
Magnetic skyrmion, particle-like topologically non-trivial spin textures, attracts surge of interests from both fundamental and application points of view. Since the first discovery in MnSi crystallizing in the cubic space group , intensive research on magnetic skyrmions has conducted for materials particularly in this space group. This leads to findings of new class of materials, whereas magnetic ions were mostly limited to d electron systems. Recently, it turned out that f-electron compounds can host magnetic skyrmion lattice as well. The magnetic skyrmions in f-electron compounds possess contrasting characteristics, such as short periodicity and strong anisotropy. Among recent discoveries, cubic chiral compound EuPtSi provides ideal opportunities to compare with d-electron systems as it crystallizes in the same space group as MnSi, namely . We will present our neutron and X-ray scattering studies to characterize magnetic skyrmion lattice in this compound.
BiPark, P.*; Ortiz, B. R.*; Spargue, M.*; Sakuya, A. P.*; Chen, S. A.*; Frontzek, M. D.*; Tian, W.*; Sibille, R.*; Mazzone, D. G.*; 田端 千紘; et al.
no journal, ,
The electronic band structure of kagome metals is the basis for a growing number of intriguing physical phenomena. Here we focus on the case of Ce pseudospin-1/2 local moments coupled by a Ti-derived Kagome electronic structure in the material CeTiBi. Neutron scattering measurements under applied magnetic fields reveal that CeTiBi exhibits a rich temperature-field phase diagram where an incommensurate spin-density wave (SDW) ground state coexists with a commensurate magnetic modulation. Remarkably, ARPES and DFT investigations reveal that the van Hove singularities (VHSs) of the kagome bands near the Fermi level are nested by vectors which coincide with the observed magnetic propagation vectors. This correspondence suggests a VHS-driven mechanism for SDW formation and provides an interesting counterpart to the charge density waves observed in other kagome metals. Our results establish that CeTiBi offers a rare opportunity to explore intertwined kagome Fermiology and quantum-magnetic spin textures.
OProkhnenko, 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.
no journal, ,
The spin dynamics in the natural mineral aegirine, NaFeSiO, which exhibits multiferroic properties, was studied using elastic and inelastic neutron scattering. Magnetism in pyroxenes arises from competing intra- and interchain exchanges that stabilize a variety of commensurate and incommensurate states. The incommensurate helical ground state remains robust, with no metamagnetic transitions observed and only gradual spectral changes under field. A phase diagram constructed in terms of the exchange ratios 
and 
captures the transition between commensurate and incommensurate regimes and unifies magnetic behavior across different pyroxenes. Despite structural variations (
vs 
), the exchange topology and resulting magnetic frustration are closely related. These results establish NaFeSiO as a benchmark for understanding exchange-driven magnetism and field-stable spin dynamics in pyroxenes with three-dimensional magnetic coupling.
における磁気スキルミオン格子(=Si,Ge)金子 耕士; 田端 千紘; Frontzek, M. D.*; 松田 雅昌*; 大石 一城*; 伊藤 孝; 宗像 孝司*; 鬼柳 亮嗣; 垣花 将司*; 辺土 正人*; et al.
no journal, ,
トリリウム格子化合物EuPt(=Si,Ge)は、磁気スキルミオンの典型物質MnSiと同じ空間群に属し、有限磁場・温度のみで存在する特異な磁場誘起秩序相をもつ。巨大なホール抵抗に加え、中性子・共鳴X線による研究から、この磁場誘起秩序相において磁気スキルミオン格子が実現していることを報告した。MnSiなどのd電子系と比べ、1/10程度の極めて短周期であることに加え、強い印加磁場異方性の存在など異なる特徴を有していることから、新たなメカニズムによる形成が示唆されている。最近Gd化合物を中心にf電子系での磁気スキルミオン化合物が相次いで発見され、短周期など共通する特徴が見出される一方で、EuPtXでは印加磁場方向により、ホール異常を伴う複数の磁場誘起秩序相の存在や、立方晶としては極めて低対称の秩序波数(
=(0.09, 0.20, -0.28))など、固有の特徴が見出されている。今回、磁場誘起秩序相について、単結晶中性子回折、小角散乱を駆使し、異方性を中心に調べた結果を報告する。
金子 耕士; 田端 千紘*; 大石 一城*; 伊藤 孝; 中尾 裕則*; Frontzek, M. D.*; 松田 雅昌*; 宗像 孝司*; 中尾 朗子*; 大原 高志; et al.
no journal, ,
MnSiと同じ空間群に属する立方晶化合物EuPtSiでは、有限磁場・温度領域でのみ安定化する特徴的な磁場誘起秩序相であるA相が現れ、輸送特性, 中性子, X線回折から、磁気スキルミオン格子が実現していることが確認された。MnSiの磁気スキルミオン相と比べ、EuPtSi固有の特徴の一つは、強い異方性をもつことである。この点について、磁場中中性子散乱で調べた微視的な構造変化を報告する。
