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清水 悠晴*; 橘高 俊一郎*; 河野 洋平*; 中村 翔太*; 芳賀 芳範; 山本 悦嗣; 町田 一成*; 網塚 浩*; 榊原 俊朗*
Physical Review B, 112(24), p.245157_1 - 245157_10, 2025/12
We report the results of high-resolution dc magnetization and specific heat measurements on the unconventional superconductor UBe.Suppression of the non-Fermi-liquid behavior under field and a nontrivial fifth-order magnetic susceptibility were observed at low temperatures, suggesting the Fermi-surface reconstruction accompanying the crossover from non-Fermi-liquid to Fermi-liquid state in UBe.
Be nuclear magnetic resonance in UBe; Itinerant-localized duality and possible Fermi surface reconstruction at high magnetic field松木 麟太朗*; 南 晶子*; 小手川 恒*; 播磨 尚朝*; 芳賀 芳範; 山本 悦嗣; 大貫 惇睦*; 藤 秀樹*
Journal of the Physical Society of Japan, 94(12), p.124702_1 - 124702_8, 2025/11
We report on new results of Be nuclear magnetic resonance measurements conducted on a single crystal of the heavy fermion superconductor UBe. A comparison between the knight shift and the classical dipolar shift provides microscopic evidence for the nature of an itinerant-localized duality in UBe. Furthermore, a reconstruction of part of the multiple Fermi surfaces in the high-magnetic-field region is suggested.
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：22 パーセンタイル：98.08(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.
Eaton, A. G.*; Weinberger, T. I.*; Popiel, N. J. M.*; Wu, Z.*; Hickey, A. J.*; Cabala, A.*; Posp
il, J.*; Prokleka, J.*; Haidamak, T.*; Bastien, G.*; et al.
Nature Communications (Internet), 15, p.223_1 - 223_10, 2024/01
Fermi surfaces (FSs) of the anomalous UTe were successfully detected using quantum oscillation technique on an ultrapure single crystal. The shape of FS was reproduced from the experimental data revealing two cylindrical quasi-two-dimensional FSs. This analysis suggests that a fairly strong nesting nature possibly leading to magnetic fluctuations responsible for the triplet superconductivity.
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：42 パーセンタイル：98.19(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。
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。
-electron systems大貫 惇睦*; 摂待 力生*; 芳賀 芳範; 竹内 徹也*; 辺土 正人*; 仲間 隆男*
Quantum Science; The Frontier of Physics and Chemistry, p.21 - 63, 2022/10
Fermi surfaces of -electron systems and the novel physical properties related with crystal symmetry, electronic correlations and magnetic interactions are reviewed. The key materials are CeRhIn
, CeIr
, EuCuGe and EuPtSi.
青木 大*; 酒井 宏典; Opletal, P.; 常盤 欣文; 石塚 淳*; 柳瀬 陽一*; 播磨 尚朝*; 仲村 愛*; Li, D.*; 本間 佳哉*; et al.
Journal of the Physical Society of Japan, 91(8), p.083704_1 - 083704_5, 2022/08
被引用回数：63 パーセンタイル：98.01(Physics, Multidisciplinary)de Haas-van Alphen oscillation was successfully observed in an unconventional superconductor UTe using high-quality single crystals. From this observation, Fermi surfaces of this compound were determined to be cylinders elongated along the c-direction, in consistent with theoretical expectation. However, the extremely large cyclotron effective masses ranging 32 to 57 m
, in consistent with the electronic specific heat, far exceed calculated values.
芳賀 芳範; Opletal, P.; 常盤 欣文; 山本 悦嗣; 徳永 陽; 神戸 振作; 酒井 宏典
Journal of Physics; Condensed Matter, 34(17), p.175601_1 - 175601_7, 2022/04
被引用回数：32 パーセンタイル：87.01(Physics, Condensed Matter)Single crystals of the unconventional superconductor UTe have been grown in various conditions. Superconducting samples are nearly stoichiometric within an experimental error of about 1%, while non-superconducting sample significantly deviates from the ideal composition. The superconducting UTe showed that the large density of states was partially gapped in the normal state, while the non-superconducting sample is characterized by the relatively large electronic specific heat as reported previously.
野間 雄一郎*; 小手川 恒*; 久保 徹郎*; 藤 秀樹*; 播磨 尚朝*; 芳賀 芳範; 山本 悦嗣; 大貫 惇睦*; 伊藤 公平*; 仲村 愛*; et al.
Journal of the Physical Society of Japan, 90(7), p.073707_1 - 073707_5, 2021/07
被引用回数：1 パーセンタイル：19.60(Physics, Multidisciplinary)Ferromagnetic fluctuation relevant to the pressure-induced superconductivity in UGe is investigated by means of NMR spectroscopy. Longitudinal magnetic fluctuations were observed in the spin-echo decay rate near the ferromagnetic critical point where superconductivity takes place. This result strongly suggests that superconductivity in ferromagnets is universally mediated by anisotropic magnetic fluctuations.
Rh
Ge ferromagnets in magnetic field along the 
axisPospil, J.*; 芳賀 芳範; 三宅 厚志*; 神戸 振作; 徳永 陽; 徳永 将史*; 山本 悦嗣; Proschek, P.*; Voln
, J.*; Sechovsk, V.*
Physical Review B, 102(2), p.024442_1 - 024442_13, 2020/07
被引用回数：7 パーセンタイル：31.62(Materials Science, Multidisciplinary)Alloying study of ferromagnetic superconductors URhGe and UCoGe is reported. The Curie temperature shows a maximum at Rh concentration 
= 0.4 in UCoRhGe. Magnetic characteristices in low- and high- regions are significantly different each other. The relationship between magnetism and superconductivity are discussed.
青山 泰介*; 小手川 恒*; 藤 秀樹*; 木村 憲彰*; 芳賀 芳範; 山本 悦嗣; 大貫 惇睦*
Physica B; Condensed Matter, 570, p.349 - 351, 2019/10
被引用回数：1 パーセンタイル：3.56(Physics, Condensed Matter)
Pt-NMR measurements are performed on a heavy fermion superconductor UPt to investigate the in-plane anistropy. A splitting of the NMR line was observed and explained by anisotropic Knight shift tensors associated with the local symmetry of the Pt site.
; Pt-NMR study青山 泰介*; 小手川 恒*; 木村 憲彰*; 山本 悦嗣; 芳賀 芳範; 大貫 惇睦*; 藤 秀樹*
Journal of the Physical Society of Japan, 88(6), p.064706_1 - 064706_7, 2019/06
被引用回数：2 パーセンタイル：17.16(Physics, Multidisciplinary)Pt-NMR measurements under magnetic field (
) parallel to the 
-axis in the vicinity of the upper critical field 
have been carried out on the heavy-fermion superconductor UPt. The quasiparticle spin susceptibility was obtained from the measurements. The field dependence of the susceptibility suggests that the 
-vector freely rotates in magnetic field. It is therefore concluded that spin-orbit interaction, which confines the direction of the -vector with respect to the crystal axis, is weak in UPt.
中村 翔太*; 榊原 俊郎*; 清水 悠晴*; 橘高 俊一郎*; 河野 洋平*; 芳賀 芳範; Pospisil, J.; 山本 悦嗣
Progress in Nuclear Science and Technology (Internet), 5, p.123 - 127, 2018/11
Dc magnetization measurements have been performed on the orthorhombic Ising ferromagnet Urge. We observed a clear first-order reorientation transition with a small hysteresis and estimated the tricritical point to be around 4 K. The magnetization and the thermal expansion data indicate the presence of a characteristic temperature of about 1 K.
; 
Ge-NQR study at ambient pressure野間 雄一郎*; 小手川 恒*; 久保 徹郎*; 藤 秀樹*; 播磨 尚朝*; 芳賀 芳範; 山本 悦嗣; 大貫 惇睦*; 伊藤 公平*; Haller, E. E.*; et al.
Journal of the Physical Society of Japan, 87(3), p.033704_1 - 033704_5, 2018/03
被引用回数：4 パーセンタイル：31.58(Physics, Multidisciplinary)Ge nuclear quadrupole resonance study of ferromagnetic superconductor UGe is reported. Detailed analyses successfully assigned crystallographic sites of Ge atoms. The measurement of the nuclear spin-lattice relaxation rate revealed highly anisotropic magnetic fluctuations.
郷地 順*; 住山 昭彦*; 山口 明*; 本山 岳*; 木村 憲彰*; 山本 悦嗣; 芳賀 芳範; 大貫 惇睦
Physical Review B, 93(17), p.174514_1 - 174514_5, 2016/05
被引用回数：2 パーセンタイル：9.35(Materials Science, Multidisciplinary)The Josephson effect between a single crystal UPt and a conventional superconductor Al has been investigated under pressure. A possible change of the superconducting order parameter has been detected at a critical 
where the symmetry-breaking antiferromagnetic order disappears. The conclusion is also supported by the different behaviors observed in Josephson current and penetration depth.
-wave superconductivity in URuSi from the field-angle variation of its specific heat橘高 俊一郎*; 清水 悠晴*; 榊原 俊郎*; 芳賀 芳範; 山本 悦嗣; 大貫 惇睦; 堤 康雅*; 野本 拓也*; 池田 浩章*; 町田 一成*
Journal of the Physical Society of Japan, 85(3), p.033704_1 - 033704_4, 2016/03
被引用回数：35 パーセンタイル：82.09(Physics, Multidisciplinary)Low-energy quasiparticle excitations in the heavy-fermion superconductor URuSi were investigated by specific heat measurements as a function of temperature, magnetic field and its angle. Experimental results agree with the theoretical model for a superconducting gap with chiral -wave symmetry.
Co照屋 淳志*; 垣花 将司*; 竹内 徹也*; 青木 大*; 本多 史憲*; 仲村 愛*; 芳賀 芳範; 松林 和幸*; 上床 美也*; 播磨 尚朝*; et al.
Journal of the Physical Society of Japan, 85(3), p.034706_1 - 034706_10, 2016/03
被引用回数：10 パーセンタイル：54.40(Physics, Multidisciplinary)Superconducting characteristics and Fermi surfaces of ZrCo are experimentally studied on a single crystal sample grown by Bridgman technique. Thermodynamic quantities in the superconducting state such as specific heat and magnetization show deviation from a single-gap the BCS model and can be attributed on the band structure with the dominant contribution of Zr-4 and Co-3 components.
probed by static dc magnetization measurements清水 悠晴*; 芳賀 芳範; 柳澤 達也*; 網塚 浩*
Physical Review B, 93(2), p.024502_1 - 024502_8, 2016/01
被引用回数：8 パーセンタイル：33.93(Materials Science, Multidisciplinary)Static dc magnetization measurements were performed for a heavy fermion superconductor UBe single crystal. For the fields along the [100] and [110] directions of cubic lattice, a magnetic anomaly was found at a characteristic field 
within the superconducting mixed state. It was also found that magnetic anisotropy became more significant above this field. The present study shows that the thermodynamic property of superconductivity changes as a function of magnetic field.
Si revealed by comparison with nonmagnetic references ThRuSi and LaRuSi江見 直哉*; 濱端 良輔*; 中山 大将*; 三木 俊宙*; 小山 岳秀*; 上田 光一*; 水戸 毅*; 小堀 洋*; 松本 裕司*; 芳賀 芳範; et al.
Journal of the Physical Society of Japan, 84(6), p.063702_1 - 063702_4, 2015/06
被引用回数：10 パーセンタイル：55.44(Physics, Multidisciplinary)NMR/NQR measurements have been carried out on ThRuSi and LaRuSi which are the nonmagnetic references of the heavy fermion URuSi. Ru-NQR measurements suggest the relatively close electronic configuration between ThRuSi and URuSi at high temperature. However, significant delocalization was observed in URuSi at low temperatures. Si-NMR experiments on URuSi revealed Ising-like spin fluctuations in the hidden-order state.
