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筒井 智嗣; 伊藤 孝; 中村 仁*; 吉田 実生*; 小林 義男*; 依田 芳卓*; 中村 惇平*; 幸田 章宏*; 東中 隆二*; 青木 大*; et al.
Interactions (Internet), 245(1), p.55_1 - 55_9, 2024/12
Sm SR-based Mssbauer and muon spin relaxation (SR) spectroscopies have been applied to SmRuGe. The temperature dependence of the Sm SR-based Mssbauer spectra in the paramagnetic state implies the presence of dynamical nuclear Zeeman and/or quadrupole interactions. The time differential SR spectra also exhibit a marked temperature dependence in the paramagnetic state, indicating the presence of magnetic fluctuation in SmRuGe at least. These results in the present work infer that the dynamical hyperfine interactions observed using the mutually complementary spectroscopic methods are connected with the mechanism of the heavy fermion behavior in SmRuGe.
筒井 智嗣; 東中 隆二*; 水牧 仁一朗*; 小林 義男*; 中村 仁*; 伊藤 孝; 依田 芳卓*; 松田 達磨*; 青木 勇二*; 佐藤 英行*
Interactions (Internet), 245(1), p.9_1 - 9_10, 2024/12
Sm synchrotron-radiation-based Mssbauer spectroscopy has been applied to Sm-based heavy fermion intermetallics, SmAl ( = Ti, V and Cr) and SmOsSb. The isomer shifts obtained demonstrate that the Sm valence states in these compounds are intermediate. Since the difference of the isomer shifts in 22.502 keV Sm Mssbauer effect between Sm and Sm state is comparable to the 2nd order Doppler shift, consideration of the 2nd order Doppler shift is required to precisely discuss Sm valence state through the shifts of the Mssbauer spectra. In addition, the plots of the isomer shifts obtained by the Mssbauer spectroscopy against the Sm valence states estimated from Sm L-edge X-ray absorption spectroscopy exhibit a linear correlation except for that in SmOsSb. This implies that the origin of the intermediate valence state in SmOsSb differs from that in SmAl ( = Ti, V and Cr).
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:22 パーセンタイル:97.82(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。
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:44 パーセンタイル:97.97(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.
中村 翔太*; 兵頭 一志*; 松本 裕司*; 芳賀 芳範; 佐藤 仁*; 上田 茂典*; 三村 功次郎*; 斉木 克祥*; 磯 孝斉*; 山下 穣*; et al.
Journal of the Physical Society of Japan, 89(2), p.024705_1 - 024705_5, 2020/02
被引用回数:2 パーセンタイル:19.65(Physics, Multidisciplinary)We have succeeded in growing a new heavy fermion compound YbNiSi by the flux method. From electrical resistivity, magnetization, specific heat, magnetic torque and X-ray photoemission measurements concluded that this compound is a heavy fermion compound exhibiting an antiferromagnetic order at 0.35 K.
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:0 パーセンタイル:0.00(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.
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:1 パーセンタイル:10.61(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.
小泉 昭久*; 久保 康則*; 山本 悦嗣; 芳賀 芳範; 櫻井 吉晴*
Journal of the Physical Society of Japan, 88(3), p.034714_1 - 034714_6, 2019/03
被引用回数:2 パーセンタイル:19.46(Physics, Multidisciplinary)Directional Compton profiles of a heavy fermion compound UPdAl are measured in the basal plane of the hexagonal lattice. A remarkable change of the two-dimensional electron occupation number densities has been observed between 20 K and 100 K. Obtained results are attributed to the modification of the 5 electronic states.
Pospil, J.*; 芳賀 芳範; 小濱 芳允*; 三宅 厚志*; 神戸 振作; 立岩 尚之; Valika, M.*; Proschek, P.*; Prokleka, J.*; Sechovsk, V.*; et al.
Physical Review B, 98(1), p.014430_1 - 014430_7, 2018/07
被引用回数:16 パーセンタイル:58.81(Materials Science, Multidisciplinary)The metamagnetic transition between the antiferromagnetic and paramagnetic state in UIrGe has been studied at various temperatures by magnetization, heat capacity, and magnetocaloric effect measurements on a single crystal in static and pulsed magnetic fields applied along the orthorhombic axis. The first-order transition is accompanied by a dramatic increase of the Sommerfeld coefficient. A tentative scenario explaining these anomalies by antiferromagnetic correlations or short-range order in the paramagnetic state is discussed.
伊覇 航*; 屋良 朝之*; 安次富 洋介*; 垣花 将司*; 竹内 徹也*; 本多 史憲*; 仲村 愛*; 青木 大*; 郷地 順*; 上床 美也*; et al.
Journal of the Physical Society of Japan, 87(6), p.064706_1 - 064706_14, 2018/06
被引用回数:19 パーセンタイル:73.58(Physics, Multidisciplinary)We succeeded in growing single crystals of the series of EuCu(GeSi) compounds.Physical property measurements demonstrate a maximum of the antiferromagnetic transition temperature appears at . Antiferromagnetism then disappears around followed by a heavy-fermion formation at higher concentrations. These observations follow the Doniach phase diagram as a function of .
Kim, H.*; 吉田 靖雄*; Lee, C.-C.*; Chang, T.-R.*; Jeng, H.-T.*; Lin, H.*; 芳賀 芳範; Fisk, Z.*; 長谷川 幸雄*
Science Advances (Internet), 3(9), p.eeao0362_1 - eeao0362_5, 2017/09
被引用回数:14 パーセンタイル:64.62(Multidisciplinary Sciences)We report a first, real-space, imaging of an orbital ordered structure on a cobalt-terminated surface of the well-studied heavy fermion compound CeCoIn. Within small tip-sample distances, the cobalt atoms on a cleaved (001) surface take on dumbbell shapes alternatingly aligned in the [100] and [010] directions in scanning tunneling microscopy topographies. First-principles calculations reveal that this staggered orbital order is triggered by enhanced on-site Coulomb interaction at the surface.
松本 裕司*; 芳賀 芳範; 立岩 尚之; 青木 晴善*; 木村 憲彰*; 山村 朝雄*; 山本 悦嗣; 松田 達磨*; Fisk, Z.*; 山上 浩志*
Journal of the Physical Society of Japan, 85(10), p.104709_1 - 104709_7, 2016/10
被引用回数:3 パーセンタイル:26.69(Physics, Multidisciplinary)dHvA oscillations were detected on an actinide compound ThRuSi which is regarded as a reference to strongly correlated electron systems URuSi and CeRuSi. Observed Fermi surfaces well coincides with the band structure calculations, as well as experimentally obtained ones for a heavy fermion compound CeRuSi. On the other hand, Fermi surfaces of URuSi have significantly different characteristics, suggesting an itinerant ground state of 5f electrons.
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:1 パーセンタイル:4.89(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.
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:32 パーセンタイル:82.34(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.
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:36.30(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.
広瀬 雄介*; 竹内 徹也*; 本多 史憲*; 吉内 伸吾*; 萩原 政幸*; 山本 悦嗣; 芳賀 芳範; 摂待 力生*; 大貫 惇睦
Journal of the Physical Society of Japan, 84(7), p.074704_1 - 074704_10, 2015/07
被引用回数:6 パーセンタイル:44.19(Physics, Multidisciplinary)Magnetic phase diagram of two heavy fermion metamagnets UIrZn and UCoZn is investigated. UIrZn shows a reconstruction of the electronic states across the metamagnetic crossover. However, UCoZn shows a rather continuous evolution. The remarkable difference in both compounds can be accounted for by different degree of hybridization between 5 and ligand electrons.
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:57.36(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.
井澤 公一*; 町田 洋*; 伊藤 淳史*; 宗 義尚*; 多田 勝哉*; 芳賀 芳範; 山本 悦嗣; 木村 憲彰*; 大貫 惇睦; 堤 康雅*; et al.
Journal of the Physical Society of Japan, 83(6), p.061013_1 - 061013_8, 2014/06
被引用回数:23 パーセンタイル:75.25(Physics, Multidisciplinary)Recent advances on the study of the gap symmetry in UPt by thermal conductivity tensors are reported. The field-angle-resolved thermal conductivity shows spontaneous twofold symmetry breaking i the gap function for the high-field C-phase, indicating the pairing symmetry of UPt belongs to an representation in the -wave category.
松田 康弘*; 中村 俊幸*; 久我 健太郎*; 中辻 知*; 道村 真司*; 稲見 俊哉; 河村 直己*; 水牧 仁一朗*
Journal of the Korean Physical Society, 62(12), p.1778 - 1781, 2013/06
被引用回数:10 パーセンタイル:55.16(Physics, Multidisciplinary)-および-YbAlB中のYbイオンの価数をX線吸収および発光分光で2Kから280Kの温度範囲で測定した。価数は温度とともに3価に向かってゆっくり増加し、価数揺動の特性温度は約290Kと分かった。40Kで32Tまでの磁場を印可しYbの価数のわずかな増加(0.002)も観測した。