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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(Physics, Condensed Matter)We investigated the ternary uranium compounds UAl ( = Fe, Ru and Os) with the orthorhombic YbFeAl-type crystal structure. URuAl and UOsAl 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 UAl ( = Fe, Ru and Os) has non-magnetic ground states.
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:33.8(Physics, Condensed Matter)Metamagnetic behavior of the heavy fermion compound YbIrZn has been studied experimentally. The metamagnetic transition was clearly seen in the bulk magnetization curve. Near the metamagnetic critical field H 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.
清水 悠晴*; 池田 陽一*; 若林 琢巳*; 天谷 健一*; 芳賀 芳範; 日高 宏之*; 柳澤 達也*; 網塚 浩*
Journal of Physics; Conference Series, 273, p.012084_1 - 012084_4, 2011/02
被引用回数:3 パーセンタイル:62.63(Physics, Condensed Matter)Static dc magnetization measurements in the superconducting mixed state of a single crystal UBe were performed by means of a capacitance Faraday-force method down to 0.24 K. Below the upper critical field , not only a peak effect but also an additional broad anomaly have been observed in magnetization curves. We report superconducting phase diagram of UBe obtained by our magnetization measurements, including these anomalies.
吉田 力矢*; 中村 祥明*; 福井 仁紀*; 芳賀 芳範; 山本 悦嗣; 大貫 惇睦; 大川 万里生*; Shin, S.*; 平井 正明*; 村岡 祐治*; et al.
Journal of Physics; Conference Series, 273, p.012021_1 - 012021_4, 2011/02
被引用回数:1 パーセンタイル:33.8(Physics, Condensed Matter)Electronic structures of U(RuRh)Si is studied employing ultrahigh-resolution laser angle-resolved photoemission spectroscopy. A hole-like dispersive feature, which presumably has Rh -band character, was observed.However, although a heavy quasiparticle band appears in the hidden-order state of URuSi ( = 0), it was not observed for = 0.03 over the temperature range studied.
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.
Journal of Physics; Conference Series, 273, p.012067_1 - 012067_4, 2011/02
被引用回数:3 パーセンタイル:62.63(Physics, Condensed Matter)これまでYb2価物質であると考えられてきたYbCuGeについて、Yb4電子を含む固体内部の電子構造を調べるために軟X線光電子分光実験を行った。その結果、角度積分スペクトルの結合エネルギーの612eVにわずかにYb多重項ピークが観測された。これはYbCuGeは価数揺動物質であることを示している。また、角度分解スペクトルにおいてYb4バンドと伝導バンドが"anti-crossing"している様子が確認できた。これは、Ge4とCu3でできた伝導バンドとYb4バンドが混成していることを示す。
岡崎 竜二*; 下澤 雅明*; 宍戸 寛明*; Konczykowski, M.*; 芳賀 芳範; 松田 達磨; 山本 悦嗣; 大貫 惇睦; 柳瀬 陽一*; 芝内 孝禎*; et al.
Journal of Physics; Conference Series, 273, p.012081_1 - 012081_4, 2011/02
被引用回数:3 パーセンタイル:62.63(Physics, Condensed Matter)The low critical field in ultraclean URuSi single crystals with residual resistivity ration exceeding 700 is precisely determined. The whole for can be explained by the two-gap with line and point nodes. In contrast, for a distinct kink in the slope of was found at 1.2 K, which cannot be accounted for by the two-gap. This outstanding anomaly demonstrates a highly unusual superconducting state embedded in the hidden order state possibly related to the time reversal symmetry breaking.
立岩 尚之; 松田 達磨; 芳賀 芳範; 山本 悦嗣; 大貫 惇睦
Journal of Physics; Conference Series, 273, p.012087_1 - 012087_5, 2011/02
被引用回数:4 パーセンタイル:70.74(Physics, Condensed Matter)URuSiの高圧下電気抵抗測定を高純度単結晶試料を用いて行った。圧力相図を再検討した。圧力を加えると、隠れた秩序相への相転移温度は増大し、超伝導転移温度は単調に減少してゆく。基底状態が隠れた秩序相である臨界圧力未満では、電気抵抗の温度のべきは2より小さくなることが明らかにされた。これは通常のフェルミ流体理論と異なる結果であり、隠れた秩序相の特性であることが明らかにされた。
芳賀 芳範
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AnPdAl compounds (An = rare earths and actinides) crystallize in the tetragonal ZrNiAl-type structure. Among them, NpPdAl is the first Np compound that shows heavy fermion superconductivity. The strongly Pauli-limited upper critical fields (Hc) reflecting the magnetic anisotropy and the first-order phase transition at Hc are very similar characteristics as observed in other heavy fermions. Detailed magnetic and superconducting study for these compounds including new experimental developments particularly for the transuranium compounds will be discussed.