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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.
Vali
ka, M.*; Haidamak, T.*; Cabala, A.*; Posp
il, J.*; Bastien, G.*; Sechovsk
, V.*; Prokleka, J.*; 柳澤 達也*; Opletal, P.; 酒井 宏典; et al.
Physical Review Materials (Internet), 8(9), p.094415_1 - 094415_9, 2024/09
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)Elastic responses at the metamagnetic transition in UTe are studied at high field. The elastic anomaly becomes the strongest at the critical-end-point. Similar behavior was also observed in another metamagnet UCoAl, suggesting a universal elastic response triggered by critical magnetic fluctuations.
竹内 徹也*; 本多 史憲*; 青木 大*; 芳賀 芳範; 木田 孝則*; 鳴海 康雄*; 萩原 政幸*; 金道 浩一*; 軽部 皓介*; 播磨 尚朝*; et al.
Journal of the Physical Society of Japan, 93(4), p.044708_1 - 044708_10, 2024/04
被引用回数：0 パーセンタイル：0.00(Physics, Multidisciplinary)Electrical and magnetic properties of divalent europium antiferromagnet EuTe are studied on single crystals grown from Te-flux method. Antiferromagnetism occurs at 11 K with an insulating ground state. Application of magnetic field induces a sudden resistance drop leading to a phase transition to metallic state. Energy band calculations reveal the appearance of a Fermi surface pocket with Te-5p character induced by the polarized Eu moments.
常盤 欣文; Opletal, P.; 酒井 宏典; 神戸 振作; 山本 悦嗣; 木俣 基*; 淡路 智*; 佐々木 孝彦*; 青木 大*; 芳賀 芳範; et al.
Physical Review B, 109(14), p.L140502_1 - L140502_6, 2024/04
被引用回数：5 パーセンタイル：75.63(Materials Science, Multidisciplinary)超伝導体UTeの常伝導状態を
軸磁場に対するエントロピー解析によって調べた。メタ磁性揺らぎ(空間一様、
)による磁場によるエントロピーの強い増加が観測された。この磁場依存性は遍歴メタ磁性の量子臨界性に関するHertz-Millis-Moriya理論によってよく記述される。特に、量子臨界領域の下界は超伝導転移温度
の最小値の位置とよく一致する。この結果は、の揺らぎが超伝導を強めることを示唆している。
Pt
Ga
studied by resonant X-ray and neutron scattering田端 千紘; 今 布咲子*; 太田 玖吾*; 日比野 瑠央*; 松本 裕司*; 網塚 浩*; 中尾 裕則*; 芳賀 芳範; 金子 耕士
Physical Review B, 109(13), p.134403_1 - 134403_7, 2024/04
被引用回数：2 パーセンタイル：46.22(Materials Science, Multidisciplinary)Antiferromagnetic (AF) order of UPtGa with the ordering temperature 
= 26 K was investigated by resonant X-ray scattering and neutron diffraction on single crystals. This compound possesses a unique crystal structure in which uranium ions form honeycomb layers and then stacks along the c-axis with slight offset, which gives rise to a stacking disorder. The AF order can be described with the propagation vector of q = (1/6, 1/6, 0) in the hexagonal notation. The ordered magnetic moments orient perpendicular to the honeycomb layers, indicating a collinear spin structure consistent with Ising-like anisotropy. The magnetic reflections are found to be broadened along c
indicating that the stacking disorder results in anisotropic correlation lengths. The semiquantitative analysis of neutron diffraction intensity, combined with group theory considerations based on the crystallographic symmetry, suggests a zig-zag type magnetic structure for the AF ground state, in which the AF coupling runs perpendicular to the stacking offset, characterized as q = (1, 0, 0). The realization of the zig-zag magnetic structure implies the presence of frustrating intralayer exchange interactions involving both ferromagnetic (FM) first-neighbor and AF second and third-neighbor interactions in this compound.
末次 祥大*; 酒井 宏典; Opletal, P.; 常盤 欣文; 芳賀 芳範; 他12名*
Science Advances (Internet), 10(6), p.eadk3772_1 - eadk3772_6, 2024/02
被引用回数：10 パーセンタイル：96.78(Multidisciplinary Sciences)The superconducting gap structure of UTe was determined by the thermal conductivity measurement on ultra-clean UTe single crystals. The result demonstrates the absence of nodes around the 
-axis, contrary to the previous study. The finding reveals that UTe is likely to be a long-sought three-dimensional strong topological superconductor.
S-nuclear magnetic resonance measurements吉田 章吾*; 芳賀 芳範; 藤井 拓斗*; 中井 祐介*; 水戸 毅*; 他8名*
Journal of the Physical Society of Japan, 93(1), p.013702_1 - 013702_5, 2024/01
被引用回数：0 パーセンタイル：0.00(Physics, Multidisciplinary)In Kondo insulators, a small energy gap evolves only at low temperatures. In this study, S-nuclear magnetic resonance measurements under high pressures are performed to clarify the electronic structure of SmS. The spin-lattice relaxation time, consisting of multiple components, was analyzed based on a periodic Anderson model with Bayesian inference, leading to a peculiar small gap state arising from strong hybridization.
Pt
Al太田 玖吾*; 松本 裕司*; 渡部 悠貴*; 金子 耕士; 田端 千紘; 芳賀 芳範
New Physics; Sae Mulli, 73(12), p.1170 - 1173, 2023/12
ハニカム格子を持つ反強磁性体UPtAlの磁気構造を決定するために中性子散乱実験を行った。UPtAlは
=9Kと
=26Kで二つの相転移を示す。 
の第一相では、
=(1/3, 0, 0)の伝搬ベクトルで記述される磁気反射が観測された。のフェーズIIでは、=(1/3, 0, 0)と
=(1/2, 0, 0)の磁気反射が観測され、=(1/3, 0, 0)の磁気反射強度は弱いが有限であった。温度依存強度のヒステリシスはでの相転移にまたがって観測され、での転移が1次転移であることを示唆している。
徳永 陽; 酒井 宏典; 神戸 振作; Opletal, P.; 常盤 欣文; 芳賀 芳範; 北川 俊作*; 石田 憲二*; 青木 大*; Knebel, G.*; et al.
Physical Review Letters, 131(22), p.226503_1 - 226503_7, 2023/12
被引用回数：10 パーセンタイル：81.90(Physics, Multidisciplinary)Our measurements of 
Te NMR relaxations reveal an enhancement of electronic spin fluctuations above 
~T, leading to their divergence in the vicinity of the metamagnetic transition at 
~T, below which field-reinforced superconductivity appears when a magnetic field (
) is applied along the crystallographic axis. The NMR data evidence that these fluctuations are dominantly longitudinal, providing a key to understanding the peculiar superconducting phase diagram in 
, where such fluctuations enhance the pairing interactions.
and Eu(As
P
)大貫 惇睦*; 軽部 皓介*; 青木 大*; 仲村 愛*; 本間 佳哉*; 松田 達磨*; 芳賀 芳範; 竹内 徹也*
Journal of the Physical Society of Japan, 92(11), p.114703_1 - 114703_12, 2023/11
被引用回数：1 パーセンタイル：24.57(Physics, Multidisciplinary)Single crystal samples of a series of semimetallic magnet Eu(AsP) have successfully grown. By measuring magnetization, Hall resistivity and de Haas-van Alphen oscillations, large anomalous Hall resistivity arising from peculiar magnetic phase diagram was identified.
単結晶の純良化; 
向上と多重超伝導相図酒井 宏典; 芳賀 芳範
固体物理, 58(10), p.529 - 536, 2023/10
過剰ウランを含む溶融塩フラックス法により、高品質UTe単結晶の育成に成功した。また、この純良結晶を用いて、磁気困難軸方向に25Tまでの磁場を印加し、超伝導相図を調べた。
常盤 欣文; 酒井 宏典; 神戸 振作; Opletal, P.; 山本 悦嗣; 木俣 基*; 淡路 智*; 佐々木 孝彦*; 柳瀬 陽一*; 芳賀 芳範; et al.
Physical Review B, 108(14), p.144502_1 - 144502_5, 2023/10
被引用回数：6 パーセンタイル：60.56(Materials Science, Multidisciplinary)-軸磁場下で-軸方向の電流を用いて測定することで、スピン3重項超伝導体UTeにおけるボルテックスダイナミクスを研究した。驚くべきことに、超伝導状態の深部で、島状の臨界電流の低い領域を発見した。この現象は、ボルテックスのピンニングが弱まった結果と考えられる。特筆すべきは、この領域が最近提案された中間磁場の超伝導相と一致していることである。我々は、中間磁場超伝導状態において非特異的なボルテックスが存在する可能性を検討した。この中間状態では、複数の超伝導成分が混合するためボルテックスの中心部で超伝導の秩序パラメータが完全に消えない可能性があり、それがピニングが弱まる原因になっている可能性がある。
川崎 郁斗; 竹内 一陽*; 藤森 伸一; 竹田 幸治; 山上 浩志; 山本 悦嗣; 芳賀 芳範
Physical Review B, 108(16), p.165127_1 - 165127_9, 2023/10
被引用回数：1 パーセンタイル：0.00(Materials Science, Multidisciplinary)We performed angle-resolved photoemission spectroscopy (ARPES) experiments using soft X rays to investigate the electronic structure of the heavy-fermion superconductor UPt. The overall band structure revealed by the present ARPES measurements is compared with density-functional calculations for UPt and the non-
reference compound ThPt. We showed that the calculation for ThPt gives a better description of the experimental band structure, except for the -derived heavy quasiparticle bands. This situation is reminiscent of Ce-based heavy-fermion systems, whose band structures are often very similar to those of non-
La-based compounds. The narrow heavy quasiparticle bands are located just below the Fermi level (
), and their band structure could not be resolved by the present energy resolution. We also showed that most of the U spectral weight exists not as the coherent heavy-fermion bands but as incoherent components that distribute over a wide energy range, spanning from near to approximately 2 eV. This result indicates that the heavy quasiparticle bands are enormously renormalized by the electron correlation effect. Additionally, we showed that the spectral intensity of the heavy-fermion bands is almost temperature independent, at least up to 100 K, where the magnetic susceptibility follows a Curie-Weiss behavior.
竹田 幸治; Pospil, J.*; 山上 浩志; 山本 悦嗣; 芳賀 芳範
Physical Review B, 108(8), p.085129_1 - 085129_10, 2023/08
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)We investigated the element-specific electronic states and magnetic properties of ferromagnetic superconductor UCoGe and Ru-substituted U(Co
Ru
)Ge using soft X-ray magnetic circular dichroism (XMCD) experiments. YCoGe, a nonmagnetic compound without the 5
electrons, was also examined as a reference material. The shapes of the XMCD spectra of UCoGe at the U 
and Ge 
edges are indistinguishably similar to those of U(CoRu)Ge. On the other hand, the XMCD spectral shape at the Co 
edge is very peculiar and is changed by the existence of the U 5 electrons and the Ru substitution. From the sum rule analysis for the XMCD spectra, it was found that the magnetic moments of the U 5 and Co 3
electrons in UCoGe and U(CoRu)Ge are aligned in the same direction under the present experimental conditions; = 5.5 - 50 K and 
= 0 - 10 T. Furthermore, even in the case of YCoGe, the Co 3 electrons have a large orbital magnetic moment, suggesting that the Co 3 electrons in these compounds are in a low symmetric electronic environment originally. Through the - and -dependence of the XMCD intensity, it was revealed that the magnetic properties at the Co site are not simply induced by the magnetism at the U site and that the Co 3 electrons play an important role in the stability of ferromagnetism.
Zn
北澤 崇文; 池田 陽一*; 榊原 俊郎*; 松尾 晶*; 清水 悠晴*; 徳永 陽; 芳賀 芳範; 金道 浩一*; 南部 雄亮*; 池内 和彦*; et al.
Physical Review B, 108(8), p.085105_1 - 085105_7, 2023/08
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)We demonstrate field-induced single-ion magnetic anisotropy resulting from the multiorbital Kondo effect on diluted ytterbium alloy (LuYb)RhZn. Single-ion anisotropic metamagnetic behavior is revealed in low-temperature regions where the local Fermi-liquid state is formed. Specific heat, low-field magnetic susceptibility, and resistivity indicate reproduction of the ground-state properties by the SU(
= 8) Kondo model with a relatively large 
- hybridization of 
= 60.9 K. Dynamical susceptibility measurements on YbRhZn support realizing multiorbital Kondo ground state in (LuYb)RhZn. The single-ion magnetic anisotropy becomes evident above 
5 T, which is lower than the isotropic Kondo crossover field of 22.7 T, verifying blurred low-lying crystal field states through the multiorbital Kondo effect.
PtAl太田 玖吾*; 渡部 悠貴*; 芳賀 芳範; Iesari, F.*; 岡島 敏浩*; 松本 裕司*
Symmetry (Internet), 15(8), p.1488_1 - 1488_13, 2023/07
被引用回数：2 パーセンタイル：26.29(Multidisciplinary Sciences)Polycrystalline and single crystalline CePtAl samples were synthesized and characterized using EPMA, XRD, XAS and magnetization measurements. The valence of Ce in this compound is trivalent, in agreement with magnetic susceptibility and XAS spectra. The analysis of EXAFS spectra indicates the formation of a honeycomb lattice rather than the disordered hexagonal structure.
probed by anisotropic low-energy excitations石原 滉大*; 六本木 雅生*; 小林 雅之*; 今村 薫平*; 水上 雄太*; 酒井 宏典; Opletal, P.; 常盤 欣文; 芳賀 芳範; 橋本 顕一郎*; et al.
Nature Communications (Internet), 14, p.2966_1 - 2966_7, 2023/05
被引用回数：31 パーセンタイル：97.96(Multidisciplinary Sciences)重い電子系超伝導UTeの超伝導対称性を極低温磁場侵入長測定により研究した。異方的な低エネルギー準粒子励起が観測され、多成分カイラル超伝導を強く示唆する。このうち最も実験をよく説明するのは、カイラル非ユニタリー状態である。
平戸 未彩紀*; 横谷 明徳*; 馬場 祐治*; 森 聖治*; 藤井 健太郎*; 和田 真一*; 泉 雄大*; 芳賀 芳範
Physical Chemistry Chemical Physics, 25(21), p.14836 - 14847, 2023/05
被引用回数：2 パーセンタイル：30.03(Chemistry, Physical)To understand the mechanism underlying the high radio-sensitization of living cells possessing brominated genomic DNA, X-ray photoelectron spectroscopy was used. It was found that the bromine atom significantly reduced the energy gap between the valence and conduction states, although the core level states were not greatly affected.
along hard magnetic axis酒井 宏典; 常盤 欣文; Opletal, P.; 木俣 基*; 淡路 智*; 佐々木 孝彦*; 青木 大*; 神戸 振作; 徳永 陽; 芳賀 芳範
Physical Review Letters, 130(19), p.196002_1 - 196002_6, 2023/05
被引用回数：24 パーセンタイル：95.69(Physics, Multidisciplinary)=2.1Kのウラン2テルル化物単結晶における超伝導相図を磁気困難軸である結晶軸方向に磁場をかけて調べた。電気抵抗と交流帯磁率を同時に測定した結果、低磁場超伝導(LFSC)相と高磁場超伝導(HFSC)相が、対照的な磁場-角度依存性をもつことがわかった。結晶の純良性が上がったことにより、LFSC相の上部臨界磁場は上昇したものの、HFSC相が現れる特徴磁場
は、単結晶の純良性に関わらず、15Tと一定であることがわかった。また、近傍のLFSC相内に、弱い渦糸ピン留め力で特徴づけられる中間超伝導相を示唆する新たな相線の形跡を捉えた。
石原 滉大*; 小林 雅之*; 今村 薫平*; Konczykowski, M.*; 酒井 宏典; Opletal, P.; 常盤 欣文; 芳賀 芳範; 橋本 顕一郎*; 芝内 孝禎*
Physical Review Research (Internet), 5(2), p.L022002_1 - L022002_6, 2023/04
重い電子系超伝導UTeの下部臨界磁場
を決定した。直方晶UTeは軸が磁化容易軸であるがそれと垂直方向の磁場中ではが増強されかつ低温で上昇するという特徴を持つことを明らかにした。上部臨界磁場の異方性と比較することにより磁気揺らぎが超伝導に影響を与えていることが示唆された。
