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論文

Crossover phase diagram and electronic state in the heavy-fermion metamagnets UIr$$_2$$Zn$$_{20}$$ and UCo$$_2$$Zn$$_{20}$$

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:45.45(Physics, Multidisciplinary)

Magnetic phase diagram of two heavy fermion metamagnets UIr$$_2$$Zn$$_{20}$$ and UCo$$_2$$Zn$$_{20}$$ is investigated. UIr$$_2$$Zn$$_{20}$$ shows a reconstruction of the electronic states across the metamagnetic crossover. However, UCo$$_2$$Zn$$_{20}$$ shows a rather continuous evolution. The remarkable difference in both compounds can be accounted for by different degree of hybridization between 5$$f$$ and ligand electrons.

論文

X-ray absorption spectroscopy and novel electronic properties in heavy fermion compounds YbT$$_{2}$$Zn$$_{20}$$ (T: Rh and Ir)

本多 史憲*; 広瀬 雄介*; 三宅 厚志*; 水牧 仁一朗*; 河村 直己*; 筒井 智嗣*; 綿貫 徹; 渡辺 真仁*; 竹内 徹也*; 摂待 力生*; et al.

Journal of Physics; Conference Series, 592(1), p.012021_1 - 012021_5, 2015/03

 被引用回数:2 パーセンタイル:61.05

重い電子系化合物YbT$$_{2}$$Zn$$_{20}$$(T: Rh and Ir)について、X線吸収分光法によりYb価数観察を行った。いずれの化合物でもYb価数は温度依存性を示し、約100K以下で冷却とともにYb価数が減少する変化が見られた。これは、同型化合物であるYbCo$$_{2}$$Zn$$_{20}$$において温度依存性が見られないこととは対照的な結果である。

論文

Fermi surface, magnetic, and superconducting properties in actinide compounds

大貫 惇睦; 摂待 力生*; 芳賀 芳範; 町田 洋*; 井澤 公一*; 本多 史憲*; 青木 大*

Comptes Rendus Physique, 15(7), p.616 - 629, 2014/08

 被引用回数:6 パーセンタイル:45.09(Astronomy & Astrophysics)

Electronic state, magnetism and superconducting properties of heavy fermion compounds UPt$$_3$$, NpPd$$_5$$Al$$_2$$ and UGe$$_2$$ have been investigated. In particular, the Fermi surface study by using various experimental methods is described.

論文

Magnetic and Fermi surface properties of EuGa$$_4$$

仲村 愛*; 平仲 裕一*; 辺土 正人*; 仲間 隆男*; 三浦 泰直*; 堤 泰樹*; 森 晶宣*; 石田 一裕*; 三田村 勝哉*; 広瀬 雄介*; et al.

Journal of the Physical Society of Japan, 82(10), p.104703_1 - 104703_10, 2013/10

 被引用回数:32 パーセンタイル:80.72(Physics, Multidisciplinary)

High quality single crystals of EuGa$$_4$$ have been grown from Ga flux. Electrical resistivity, magnetic susceptibility, high-field magnetization, specific heat, thermoelectric power and de Haas-van Alphen effect were investigated. Antiferromagnetic transition due to divalent Eu atoms were observed at 16.5 K. A charge density wave transition was also found under high pressure accompanied by a Fermi surface reconstruction. These observations were fully accounted for by the Fermi surface topology and corresponding band calculations.

論文

Heavy fermions and unconventional superconductivity in high-quality single crystals of rare-earth and actinide compounds

大貫 惇睦; 摂待 力生*; 杉山 清寛*; 竹内 徹也*; 本多 史憲*; 芳賀 芳範; 山本 悦嗣; 松田 達磨; 立岩 尚之; 青木 大*; et al.

Journal of the Korean Physical Society, 63(3), p.409 - 415, 2013/08

 被引用回数:2 パーセンタイル:20.15(Physics, Multidisciplinary)

Characteristics of heavy fermion and unconventional superconductivity in rare-earth and actinide compounds are clarified by the de Haas-van Alphen experiments. The effect of pressure on the electronic states of CeRhIn$$_5$$, CeIrSi$$_3$$ and YbIr$$_2$$Zn$$_{20}$$ is studied in magnetic fields. An electronic instability occurs under pressure in these compounds.

論文

Single crystal growth and various electronic states in Yb-based compounds

広瀬 雄介*; 吉内 伸吾*; 西村 尚人*; 阪口 準也*; 榎 健太郎*; 岩川 健*; 三浦 泰直*; 杉山 清寛*; 大貫 惇睦; 摂待 力生*; et al.

Journal of the Korean Physical Society, 62(12), p.1858 - 1861, 2013/06

 被引用回数:0 パーセンタイル:0(Physics, Multidisciplinary)

We succeeded in growing single crystals of YbTIn$$_5$$ (T: Co, Rh, Ir), YbGa$$_4$$, YbT$$_2$$Zn$$_{20}$$ (T: Co, Rh, Ir), etc. The electronic and magnetic properties are clarified by measuring the electrical resistivity, magnetic susceptibility, magnetization, specific heat and de Haas-van Alphen effect.

論文

Anisotropic spin fluctuations in the heavy fermion systems; Case studies of CePd$$_5$$Al$$_2$$ and NpPd$$_5$$Al$$_2$$

酒井 宏典; 中堂 博之; 徳永 陽; 神戸 振作; 芳賀 芳範; Ronning, F.*; Bauer, E. D.*; Thompson, J. D.*; 本間 佳哉*; 青木 大*; et al.

Journal of the Physical Society of Japan, 81(Suppl.B), p.SB003_1 - SB003_6, 2012/12

 被引用回数:7 パーセンタイル:46.8(Physics, Multidisciplinary)

Ce$$T$$In$$_5$$ ($$T$$=Co, Rh, Ir)及び$$An$$$$T$$Ga$$_5$$ ($$An$$=U, Np, Pu)という化学式を持つ一連の化合物(115系と称する)、核磁気共鳴(NMR)測定の結果得られるナイトシフトと緩和率の解析から、反強磁性スピン揺らぎのXY型異方性がd波超伝導発現に有利であるとわかってきた。この仮説を確かめるために、115系化合物と類似の結晶構造を有するCePd$$_5$$Al$$_2$$とNpPd$$_5$$Al$$_2$$においてスピン揺らぎの異方性がどうなっているかを検証した。CePd$$_5$$Al$$_2$$は、イジング異方性を持つ反強磁性体であり、スピン揺らぎも同じくイジング型の異方性を示した。d波超伝導体NpPd$$_5$$Al$$_2$$は、転移温度直上の通常状態においてXY型の反強磁性磁気揺らぎを有していることがわかった。

論文

High-quality single crystal growth and unique electronic states under magnetic field and pressure in rare earth and actinide compounds

大貫 惇睦; 摂待 力生*; 竹内 徹也*; 杉山 清寛*; 本多 史憲*; 芳賀 芳範; 山本 悦嗣; 松田 達磨; 立岩 尚之; 青木 大*; et al.

Journal of the Physical Society of Japan, 81(Suppl.B), p.SB001_1 - SB001_18, 2012/12

Fermi surface properties in rare earth and actinide compounds such as CeSn$$_3$$, USi$$_3$$, NpGe$$_3$$ and PuIn$$_3$$ are clarified by the de Haas-van Alphen experiments on the bases of the energy band calculations. The pressure-induced electronic instability including unconventional superconductivity observed in CeRhIn$$_5$$ is also discussed.

論文

Fermi surface and superconducting properties of non-centrosymmetric LaNiC$$_2$$

広瀬 雄介*; 岸野 利彦*; 阪口 準也*; 三浦 泰直*; 本多 史憲*; 竹内 徹也*; 山本 悦嗣; 芳賀 芳範; 播磨 尚朝*; 摂待 力生*; et al.

Journal of the Physical Society of Japan, 81(11), p.113703_1 - 113703_4, 2012/11

 被引用回数:23 パーセンタイル:73.65(Physics, Multidisciplinary)

Fermi surface and superconducting properties were investigated on an non-centrosymmetric LaNiC$$_2$$ compound. Reflecting the crystal structure characteristics, the Fermi surfaces are split due to the antisymmetric spin-orbit interaction. On the other hand, thermodynamic property in the superconducting state follow the conventional BCS theory despite the splitting of Fermi surfaces.

論文

Electrical and magnetic properties of quasicrystal approximants RCd$$_6$$ (R: rare earth)

森 晶宣*; 太田 尚志*; 吉内 伸吾*; 岩川 健*; 田賀 悠記*; 広瀬 雄介*; 竹内 徹也*; 山本 悦嗣; 芳賀 芳範; 本多 史憲*; et al.

Journal of the Physical Society of Japan, 81(2), p.024720_1 - 024720_10, 2012/02

 被引用回数:38 パーセンタイル:83.07(Physics, Multidisciplinary)

Single crystals of quasicrystal approximants RCd$$_6$$ (R: rare earths) were prepared using the self-flux method and subsequent annealing. A structural transition was confirmed in some of these crystals. Antiferromagnetic ordering was observed for R = Nd, Sm, Tb and Dy. It was found that the structural order-disorder transition has a great influence on the magnetic ordering and transport properties.

論文

Characteristic heavy fermion properties in YbCu$$_2$$Si$$_2$$ and YbT$$_2$$Zn$$_{20}$$ (T: Co, Rh, Ir)

大貫 惇睦; 安井 慎一*; 松下 昌輝*; 吉内 伸吾*; 大家 政洋*; 広瀬 雄介*; Dung, N. D.*; 本多 史憲*; 竹内 徹也*; 摂待 力生*; et al.

Journal of the Physical Society of Japan, 80(Suppl.A), p.SA003_1 - SA003_6, 2011/12

We studied the Fermi surface properties of YbCu$$_2$$Si$$_2$$ and YbCu$$_2$$Ge$$_2$$ with the tetragonal structure by measuring the de Haas-van Alphen (dHvA) oscillations, together with the energy band calculations. It was clarified that 4f electrons contribute to the Fermi surface of a valence fluctuating compound YbCu$$_2$$Si$$_2$$, but not to that of a divalent compound YbCu$$_2$$Ge$$_2$$. We also studied the heavy fermion properties of YbT$$_2$$Zn$$_{20}$$ (T: Co, Rh, Ir) with the cubic caged structure. The metamagnetic behavior or an abrupt nonlinear increase of magnetization was observed. By measuring the electrical resistivity under pressure and magnetic field, we clarified that the electronic state close to the quantum critical point is realized in YbIr$$_2$$Zn$$_{20}$$ at 5.2 GPa and also YbCo$$_2$$Zn$$_{20}$$ at ambient pressure.

論文

High field magnetoresistance and de Haas-van Alphen effect in LaRu$$_2$$Al$$_{10}$$

迫田 將仁*; 田中 修平*; 松岡 英一*; 菅原 仁*; 播磨 尚朝*; 本多 史憲*; 摂待 力生*; 大貫 惇睦; 松田 達磨; 芳賀 芳範

Journal of the Physical Society of Japan, 80(8), p.084716_1 - 084716_5, 2011/08

 被引用回数:8 パーセンタイル:50.85(Physics, Multidisciplinary)

Magnetoresistance and de Haas-van Alphen (dHvA) effect were studied to investigate Fermi surface topology in LaRu$$_2$$Al$$_{10}$$. From the positive magnetoresistance in a wide angular region, this compound is regarded as a compensated metal. On the other hand, dHvA measurement shows several Fermi surface branches with a cyclotron effective mass close to the electron rest mass. The Fermi surface topology was well explained by the band calculations.

論文

Magnetic-field-induced metallic state in $$beta$$-US$$_2$$

杉山 清寛*; 広瀬 雄介*; 榎 健太郎*; 池田 修悟*; 山本 悦嗣; 立岩 尚之; 芳賀 芳範; 木田 孝則*; 萩原 政幸*; 金道 浩一*; et al.

Journal of the Physical Society of Japan, 80(Suppl.A), p.SA104_1 - SA104_3, 2011/07

 被引用回数:3 パーセンタイル:27.61(Physics, Multidisciplinary)

Magnetic and transport properties under high magnetic field were studied on a magnetic semiconductor $$beta$$-US$$_2$$. Large magnetization reaching 1.75 $$mu_{rm B}$$ has been observed at 50 T. At the same time, resistivity decreases drastically from insulating behavior at 0 T to almost metallic characteristics at 50 T. The results are discussed based on the magnetic polaron mechanism.

論文

Single crystal growth and physical properties of ternary uranium compounds U$${M_2}$$Al$$_{10}$$ ($$M$$=Fe, Ru and Os)

菅井 孝志; 芳賀 芳範; 松田 達磨; 山本 悦嗣; 立岩 尚之; 本多 史憲*; 摂待 力生*; 大貫 惇睦

Journal of Physics; Conference Series, 273, p.012122_1 - 012122_4, 2011/02

 被引用回数:0 パーセンタイル:0.03

We investigated the ternary uranium compounds U$${M_2}$$Al$$_{10}$$ ($$M$$ = Fe, Ru and Os) with the orthorhombic YbFe$$_2$$Al$$_{10}$$-type crystal structure. URu$$_2$$Al$$_{10}$$ and UOs$$_2$$Al$$_{10}$$ are new compounds grown for the first time. These compounds show no ordering despite the Curie-Weiss behavior at high temperatures. The temperature dependence of the electrical resistivity, the specific heat and the magnetic susceptibility indicate that U$${M_2}$$Al$$_{10}$$ ($$M$$ = Fe, Ru and Os) has non-magnetic ground states.

論文

Relation between metamagnetic transition and quantum critical point in heavy fermion compound YbIr$$_2$$Zn$$_{20}$$

大貫 惇睦; 安井 慎一*; 吉内 伸吾*; 大家 政洋*; 松下 昌輝*; 広瀬 雄介*; 竹内 徹也*; 本多 史憲*; 摂待 力生*; 杉山 清寛*; et al.

Journal of Physics; Conference Series, 273, p.012013_1 - 012013_4, 2011/02

 被引用回数:1 パーセンタイル:34.07

Metamagnetic behavior of the heavy fermion compound YbIr$$_2$$Zn$$_{20}$$ has been studied experimentally. The metamagnetic transition was clearly seen in the bulk magnetization curve. Near the metamagnetic critical field H$$_m$$ $$sim$$ 100 kOe, the effective mass of conduction electrons exhibits a significant enhancements. It is suggested that the present metamagnetism is related to the magnetic instability around the quantum critical point.

論文

Magnetic and superconducting properties of CeRhGe$$_2$$ and CePtSi$$_2$$

広瀬 雄介*; 西村 尚人*; 本多 史憲*; 杉山 清寛*; 萩原 政幸*; 金道 浩一*; 竹内 徹也*; 山本 悦嗣; 芳賀 芳範; 松浦 直人*; et al.

Journal of the Physical Society of Japan, 80(2), p.024711_1 - 024711_12, 2011/02

 被引用回数:7 パーセンタイル:47.39(Physics, Multidisciplinary)

Magnetic and superconducting properties of CeRhGe$$_2$$ and CePtSI$$_2$$ have been investigated by bulk property measurements and neutron scattering experiments. CeRhGe$$_2$$ was found to order antiferromagnetically with an ordered moment 1.3 $$mu_{rm B}$$/Ce along the $$c$$-axis of the orthorhombic unit cell. High pressure resistivity measurements revealed a suppression of the antiferromagnetic transition with increasing pressure and the occurrence of superconductivity near the critical pressure where antiferromagnetism vanishes. Quantum-critical characteristics are expected to these compounds.

論文

Huge upper critical field in the superconductor with non-centrosymmetric crystal structure CeCoGe$$_3$$

M$'e$asson, M.-A.*; 村中 大志*; 松田 達磨; 河井 友也*; 芳賀 芳範; Knebel, G.*; 青木 大*; Lapertot, G.*; 本多 史憲*; 摂待 力生*; et al.

Physica C, 470(Suppl.1), p.S536 - S538, 2010/12

 被引用回数:4 パーセンタイル:22.02(Physics, Applied)

We report the upper critical field, $$H_{c2}$$, of the non-centrosymmetric compound CeCoGe$$_3$$ by resistivity measurements under high pressure of 7.1 GPa, for $$H$$ along $$c$$ and $$a$$ axis, and for a magnetic field up to 17T. $$H_{c2}$$ is very anisotropic, saturating at low temperature for $$H$$ along the $$a$$ axis and linear for $$H$$ along the $$c$$ axis. Very high $$H_{c2}$$($$T$$) is observed for $$H$$ along the $$c$$ axis, with a huge value of the slope d$$H$$$$_{c2}$$/d$$T$$ =-47 $$pm$$ 1.3 T/K, the highest ever reported if normalized to the superconducting temperature of 0.65 K. This is most probably related to a conjunction of a heavy fermionic state and the absence of the Pauli limitation. A fit of $$H_{c2}$$($$T$$) shows that the curves for a and $$c$$ axis can be reproduced with a moderate coupling Eliashberg theory.

論文

Metamagnetic behavior in heavy-fermion compound YbIr$$_2$$Zn$$_{20}$$

竹内 徹也*; 安井 慎一*; 戸田 雅敏*; 松下 昌輝*; 吉内 伸吾*; 大家 政洋*; 片山 敬亮*; 広瀬 雄介*; 吉谷 尚久*; 本多 史憲*; et al.

Journal of the Physical Society of Japan, 79(6), p.064609_1 - 064609_15, 2010/06

 被引用回数:42 パーセンタイル:83.77(Physics, Multidisciplinary)

Metamagnetic behavior of the heavy-fermion compound YbIr$$_2$$Zn$$_{20}$$ was studied by magnetization, de Haas-van Alphen effect, magnetoresistance, specific heat, thermal expansion and magnetostriction. Metamagnetic behavior was observed for all the physical properties at low temperatures. It is remarkable that the Fermi surfaces observed in the dHvA effect unchanges across the metamagnetic transition.

論文

Magnetism and superconductivity in the new family of actinide compounds; AnPd$$_{5}$$Al$$_{2}$$

芳賀 芳範; 本間 佳哉*; 青木 大*; 池田 修悟*; 松田 達磨; 立岩 尚之; 山本 悦嗣; 中村 彰夫; 中島 健次; 荒井 康夫; et al.

IOP Conference Series; Materials Science and Engineering, 9, p.012046_1 - 012046_7, 2010/05

 被引用回数:0 パーセンタイル:1.02

It is now well recognized that 5f electrons in actinide show a variety of intriguing physical properties such as heavy fermions, various magnetic and multipolar orderings and exotic superconductivity. Particularly, superconductivity in transuranium compounds are characterized by rather higher transition temperature compared to uranium- or rare-earth-based superconductor, as well as the existence of localized-like 5f paramagnetic moments following Curie-Weiss law. Among them, NpPd$$_{5}$$Al$$_{2}$$ is the first neptunium-based heavy fermion superconductor. Detailed investigations of the magnetic and thermal properties around the upper critical field have been performed. It is shown that the large anisotropic paramagnetic moment as well as electronic specific heat existing in the normal state vanish in the superconducting state, indicating a spin-singlet pairing.

論文

Heavy fermion state and quantum criticality

大貫 惇睦; 摂待 力生*; 本多 史憲*; Dung, N. D.*; 石倉 達朗*; 竹内 徹也*; 松田 達磨; 立岩 尚之; 中村 彰夫; 山本 悦嗣; et al.

Physica B; Condensed Matter, 405(9), p.2194 - 2199, 2010/05

 被引用回数:1 パーセンタイル:6.5(Physics, Condensed Matter)

The heavy fermion state in the f-electron systems is due to competition between the RKKY interaction and the Kondo effect. To understand the electronic state, we studied the Fermi surface properties via the de Haas-van Alphen (dHvA) experiments and energy band calculations for CeSn$$_{3}$$, CeRu$$_{2}$$Si$$_{2}$$, UPt$$_{3}$$, and nowadays, transuranium compounds of NpGe$$_{3}$$ and PuIn$$_{3}$$, together with YbCu$$_{2}$$Si$$_{2}$$.

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