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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:5 パーセンタイル:43.76(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:1 パーセンタイル:43.74

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:5 パーセンタイル:47.78(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

Transport properties of UT$$_2$$Zn$$_{20}$$ (T: Co, Ir)

広瀬 雄介*; 竹内 徹也*; 吉内 伸吾*; 山本 悦嗣; 芳賀 芳範; 摂待 力生*; 大貫 惇睦

JPS Conference Proceedings (Internet), 3, p.011056_1 - 011056_6, 2014/06

Transport properties of UT$$_2$$Zn$$_{20}$$ (T: Co, Ir) have been investigated by measuring Hall effect. Overall behavior is explained by the skew scattering on the impurity model at high temperatures and the periodic Anderson model at low temperatures. Rather complicated behavior was observed in UIr$$_2$$Zn$$_{20}$$ with ferromagnetic instability, implying the electronic modification under magnetic field.

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:23 パーセンタイル:16.99(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:1 パーセンタイル:84.55(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

Quadrupole effects in tetragonal crystals PrCu$$_2$$Si$$_2$$ and DyCu$$_2$$Si$$_2$$

三本 啓輔*; 後藤 沙織*; 根本 祐一*; 赤津 光洋*; 後藤 輝孝*; Dung, N. D.*; 松田 達磨; 芳賀 芳範; 竹内 徹也*; 杉山 清寛*; et al.

Journal of Physics; Condensed Matter, 25(29), p.296002_1 - 296002_8, 2013/07

 パーセンタイル:100(Physics, Condensed Matter)

We have investigated quadrupole effects in tetragonal crystals of PrCu$$_2$$Si$$_2$$ and DyCu$$_2$$Si$$_2$$ by means of low-temperature ultrasonic measurements. The elastic constant C$$_{44}$$ of PrCu$$_2$$Si$$_2$$ exhibits pronounced softening below 70 K, which is described in terms of a quadrupole susceptibility for a doublet ground state.

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

 パーセンタイル:100(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

Electronic states in antiferromagnet UCd$$_{11}$$ and reference compound ThCd$$_{11}$$; Studied by the de Haas-van Alphen effect

広瀬 雄介*; 三浦 泰直*; 堤 泰樹*; 吉内 伸吾*; 大家 政洋*; 杉山 清寛*; 竹内 徹也*; 山上 浩志*; 山本 悦嗣; 芳賀 芳範; et al.

Physica Status Solidi (B), 250(3), p.642 - 645, 2013/03

 被引用回数:3 パーセンタイル:77.51(Physics, Condensed Matter)

Electronic states of an antiferromagnet UCd$$_{11}$$ and its reference compound ThCd$$_{11}$$ were investigated by means of de Haas-van Alphen (dHvA) effect. From the cyclotron effective mass determined from the dHvA oscillation, the electronic specific heat of UCd$$_{11}$$ was estimated as 100 mJ/K$$^2$$mol, much smaller than 840 in the previous report. The result suggests that magnetic excitation contributes significantly to the specific heat.

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:3 パーセンタイル:66.83(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

Neutron scattering study on high-quality single crystals of non-centrosymmetric heavy-fermion superconductor CePt$$_{3}$$Si

金子 耕士; Stockert, O.*; Skoulatos, M.*; Schneidewind, A.*; 竹内 徹也*; 松田 達磨; 芳賀 芳範; 摂待 力生*; 大貫 惇睦; 目時 直人

Journal of the Physical Society of Japan, 81(Suppl.B), p.SB006_1 - SB006_7, 2012/12

 被引用回数:2 パーセンタイル:75.66(Physics, Multidisciplinary)

The discovery of heavy-fermion superconductivity in non-centrosymmetric compound CePt$$_3$$Si, and subsequent findings of Ce$$TX_3$$ (T: transition metal, X: Si, Ge) bring a new essence in the condensed matter physics, since a novel type of superconducting properties is expected to come out. In CePt$$_3$$Si, the compound shows an antiferromagnetic (AFM) order at $$T_{rm N }$$=2.2 K and enters into a heavy-fermion superconducting state below $$T_{rm SC}{sim}$$ 0.5 K. Through neutron scattering experiments under external magnetic field, we identified anomalous field response in CePt$$_3$$Si in the AFM state; AFM intensity showed enormous enhancement with increasing an applied field. The intensity kept increasing up to 7 T with the kink at around the additional phase boundary. These features suggest that the magnetic order in CePt$$_3$$Si is not a simple AFM one, and imply that large fraction of magnetic response could be still missing in this compound.

論文

de Haas-van Alphen effect and Fermi surface properties in V$$_{5}$$Si$$_{3}$$

堤 泰樹*; 阪口 準也*; 三浦 泰直*; 松田 達磨; 芳賀 芳範; 竹内 徹也*; 播磨 尚朝*; 摂待 力生*; 大貫 惇睦

Journal of the Physical Society of Japan, 81(Suppl.B), p.SB027_1 - SB027_4, 2012/12

 パーセンタイル:100(Physics, Multidisciplinary)

We succeeded in growing high-quality single crystals of V$$_{5}$$Si$$_{3}$$ with a high melting point of 2010 $$^{circ}$$C, and carried out the electrical resistivity, specific heat, magnetic susceptibility, and the de Haas-van Alphen measurements to clarify the electronic properties. The Fermi surface is small in volume and is well explained by the result of energy band calculations. The cyclotron mass is in the range from 5.3 to 0.2 $$m_0$$ ($$m_0$$: rest mass of an electron), consistent with the electronic specific heat coefficient $$gamma$$ = 9.7 mJ/(K$$^{2}$$$$cdot$$mol).

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:17 パーセンタイル:25.17(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:15 パーセンタイル:27.79(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

Electronic structure of YbCu$$_2$$Ge$$_2$$ studied by soft X-ray angle-resolved photoemission spectroscopy

保井 晃; 藤森 伸一; 川崎 郁斗; 岡根 哲夫; 竹田 幸治; 斎藤 祐児; 山上 浩志; 関山 明*; 摂待 力生*; 松田 達磨; et al.

Physical Review B, 84(19), p.195121_1 - 195121_6, 2011/11

 被引用回数:7 パーセンタイル:59.49(Materials Science, Multidisciplinary)

われわれは、最近になって完全なYb2価物質ではないことがわかった、YbCu$$_2$$Ge$$_2$$のバンド分散及びフェルミ面を、軟X線角度分解光電子分光を用いて3次元的に調べた。それにより、有限の4$$f$$成分を持ったバンドがフェルミ準位にかかっており、フェルミ面の形成に関与していることを明らかにした。そのことは、YbCu$$_2$$Ge$$_2$$は価数揺動物質であるという最近の報告と合致している。また、得られた価電子帯のバンド分散やフェルミ面は局所密度近似(LDA)をもとにした相対論的バンド計算でよく説明できることがわかった。これらの結果から、LDA計算はYbCu$$_2$$Ge$$_2$$をはじめとするYb2価に近い物質の電子状態の理解において、よい出発点であることが示唆される。

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:7 パーセンタイル:45.48(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:1 パーセンタイル:86.08(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

Pressure evolution of the magnetic field induced ferromagnetic fluctuation through the pseudo-metamagnetism of CeRu$$_2$$Si$$_2$$

青木 大*; Paulsen, C.*; 松田 達磨; Malone, L.*; Knebel, G.*; Haen, P.*; Lejay, P.*; 摂待 力生*; 大貫 惇睦; Flouquet, J.*

Journal of the Physical Society of Japan, 80(5), p.053702_1 - 053702_4, 2011/05

 被引用回数:15 パーセンタイル:28.21(Physics, Multidisciplinary)

Resistivity measurements performed under pressure in the paramagnetic ground state of CeRu$$_2$$Si$$_2$$ are reported. They demonstrate that the relative change of effective mass through the pseudo metamagnetic transition is invariant under pressure. The results are compared with the first order metamagnetic transition due to the antiferromagnetism of Ce$$_{0.9}$$La$$_{0.1}$$Ru$$_2$$Si$$_2$$ which corresponds to the "negative" pressure of CeRu$$_2$$Si$$_2$$ by volume expansion. Finally, we describe the link between the spin-depairing of quasiparticles on CeRu$$_2$$Si$$_2$$ and that of Cooper pairs on the unconventional heavy fermion superconductor CeCoIn$$_5$$.

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