Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Valika, M.*; Haidamak, T.*; Cabala, A.*; Posp
il, J.*; Bastien, G.*; Sechovsk
, V.*; Prokle
ka, J.*; 柳澤 達也*; Opletal, P.; 酒井 宏典; et al.
Physical Review Materials (Internet), 8(9), p.094415_1 - 094415_9, 2024/09
被引用回数:0 パーセンタイル:0.00(Materials Science, Multidisciplinary)Elastic responses at the metamagnetic transition in UTe are studied at high field. The elastic anomaly becomes the strongest at the critical-end-point. Similar behavior was also observed in another metamagnet UCoAl, suggesting a universal elastic response triggered by critical magnetic fluctuations.
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:9 パーセンタイル:97.71(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.
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:49 パーセンタイル:98.11(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:24 パーセンタイル:85.27(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.
藤森 伸一; 竹田 幸治; 山上 浩志; Pospil, J.*; 山本 悦嗣; 芳賀 芳範
Physical Review B, 105(11), p.115128_1 - 115128_6, 2022/03
被引用回数:1 パーセンタイル:8.90(Materials Science, Multidisciplinary)The electronic structure of , which is isostructural to the heavy fermion superconductor
, was investigated by photoelectron spectroscopy. The band structure and Fermi surfaces of
were obtained by angle-resolved photoelectron spectroscopy (ARPES), and the results were well-explained by the band-structure calculation based on the local density approximation. The comparison between the ARPES spectra and the band-structure calculation suggests that the Fermi surface of
mainly consists of the
and
states with a minor contribution from the
states. The comparison of the band structures between
and
argues that the
states form Fermi surfaces in
through hybridization with the
state in the
layer, suggesting that the Fermi surface of
has a strong three-dimensional nature.
松本 裕司*; 芳賀 芳範; 山本 悦嗣; 竹内 徹也*; 三宅 厚志*; 徳永 将史*
Journal of the Physical Society of Japan, 90(7), p.074707_1 - 074707_6, 2021/07
被引用回数:1 パーセンタイル:12.77(Physics, Multidisciplinary)A uranium intermetallic compound UPt
Ga
was successfully synthesized. This compound crystallizes in the hexagonal Sc
Fe
Si
-type structure. Antiferromagnetic transition with highly magnetic anisotropy was established by the physical property measurements.
Pospil, 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:37.32(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 UCo
Rh
Ge. Magnetic characteristices in low- and high-
regions are significantly different each other. The relationship between magnetism and superconductivity are discussed.
芳賀 芳範; 菅井 孝志*; 松本 裕司*; 山本 悦嗣
JPS Conference Proceedings (Internet), 29, p.013003_1 - 013003_5, 2020/02
Crystal structure and magnetic property of UPt
Al
is investigated. A single crystal X-ray diffraction experiment identified the hexagonal unit cell with a disordered structure in the uranium containing layer. A series of superstructure reflections were found. They are successfully indexed as (
/3
/3 0), however, with a streak along the
direction. A layered structure model containing honeycomb arrangement of uranium atoms is proposed. Preliminary magnetization measurements on a polycrystalline sample are also presented.
小山田 明*; 猪原 崇生*; 山本 悦嗣; 芳賀 芳範
Progress in Nuclear Science and Technology (Internet), 5, p.128 - 131, 2018/11
We report the Hall effect measurements on a triangular-lattice antiferromagnet UNiB in the context of the proposed relevance of the ferroic order. Our measurements show that the Hall voltage is proportional to the square of the electric current and its coefficient increases significantly below the transition temperature, which supports the theoretical prediction.
本山 岳*; 芳賀 芳範; 山口 明*; 川崎 郁斗*; 住山 昭彦*; 山村 朝雄*
Progress in Nuclear Science and Technology (Internet), 5, p.157 - 160, 2018/11
The crystal structure of the newly discovered compound UTiBi
was determined from single-crystal X-ray diffraction data. This compound shows an antiferromagnetic ordering at 31.5 K. A clear anomaly was observed at the transition temperature on the temperature dependence of magnetic susceptibility and electrical resistivity.
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.
松本 裕司*; 芳賀 芳範; 立岩 尚之; 山本 悦嗣; Fisk, Z.*
Journal of the Physical Society of Japan, 87(2), p.024706_1 - 024706_4, 2018/02
被引用回数:0 パーセンタイル:0.00(Physics, Multidisciplinary)Single crystal samples of UPtIn with the hexagonal structure are grown from indium flux. Strong uniaxial magnetic anisotropy is revealed from magnetic property measurements. Specific heat measurement reveals a significant deviation from -linear behavior, indicating the smaller electronic specific heat than the previous study.
Pospisil, J.; 郷地 順*; 芳賀 芳範; 本多 史憲*; 上床 美也*; 立岩 尚之; 神戸 振作; 長崎 尚子*; 本間 佳哉*; 山本 悦嗣
Journal of the Physical Society of Japan, 86(4), p.044709_1 - 044709_6, 2017/04
被引用回数:9 パーセンタイル:54.68(Physics, Multidisciplinary)The effect of hydrostatic pressure on the electronic state of the antiferromagnet UIrGe is reported. A series of resistivity measurements up to 15 GPa demonstrated the Neel temperature decreases with increasing pressure and vanishes around 12 GPa. The transition from antiferromagnetic to paramagnetic phase appears to be of first order. A moderate increase in the effective mass was detected in the vicinity of the critical pressure.
Pospisil, J.; 芳賀 芳範; 神戸 振作; 徳永 陽; 立岩 尚之; 青木 大*; 本多 史憲*; 仲村 愛*; 本間 佳哉*; 山本 悦嗣; et al.
Physical Review B, 95(15), p.155138_1 - 155138_15, 2017/04
被引用回数:15 パーセンタイル:55.27(Materials Science, Multidisciplinary)We investigated the evolution of magnetism in UIrRh
Ge system by systematic study on high-quality single crystals. We find a field-induced first order transition in the vicinity of the critical magnetic field along the
axis in the entire UIr
Rh
Ge system, including the ferromagnetic region.
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:43.85(Physics, Multidisciplinary)Magnetic phase diagram of two heavy fermion metamagnets UIrZn
and UCo
Zn
is investigated. UIr
Zn
shows a reconstruction of the electronic states across the metamagnetic crossover. However, UCo
Zn
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:56.88(Physics, Multidisciplinary)NMR/NQR measurements have been carried out on ThRuSi
and LaRu
Si
which are the nonmagnetic references of the heavy fermion URu
Si
. Ru-NQR measurements suggest the relatively close electronic configuration between ThRu
Si
and URu
Si
at high temperature. However, significant delocalization was observed in URu
Si
at low temperatures. Si-NMR experiments on URu
Si
revealed Ising-like spin fluctuations in the hidden-order state.
石井 賢司; 葛下 かおり; 村上 洋一; 芳賀 芳範; 山本 悦嗣; 大貫 惇睦
Journal of the Physical Society of Japan, 75(Suppl.), p.102 - 104, 2006/08
UPdAl
は
=14.5K以下で生じる反強磁性秩序と
=2K以下での超伝導が共存する興味深い物質である。共鳴X線磁気散乱により磁性と超伝導の結合を議論するためにも、
を越える実験の前に、それぞれの吸収端での共鳴の性質を知っておく必要がある。そのために、われわれは
においてUの
から
吸収端までの吸収端での共鳴X線磁気散乱の測定を行った。
吸収端での非常に大きな共鳴に加えて、
から
への遷移に対応する
吸収端でも共鳴が観測された。一方、
及び
吸収端での共鳴は小さいものであった。
Galatanu, A.; 芳賀 芳範; 松田 達磨; 池田 修悟; 山本 悦嗣; 青木 大*; 竹内 徹也*; 大貫 惇睦
Journal of the Physical Society of Japan, 74(5), p.1582 - 1597, 2005/05
被引用回数:39 パーセンタイル:80.01(Physics, Multidisciplinary)これまでわれわれが育成したウラン化合物について、温度800Kまでの高温磁化率測定を行った。これらの磁化率測定の結果から、ウラン化合物では5f電子状態が局在的なものからパウリ常磁性的なものまで極めて幅広い磁性がみられるが、室温以上の十分高温では、局在的なキュリーワイス則に従う振舞いに、ほとんどの物質が回復することが明らかになった。セリウム化合物と比べると、局在的な振舞いは比較的高温であることも明らかとなった。
佐伯 正克
JAERI-Review 2003-030, 50 Pages, 2003/11
本総説は、溶液系から合成可能なウラン及びネプツニウムの化合物を中心に、その合成法と性質についてまとめたものである。ウランに関しては、3価の化合物3種類,4価の化合物4種類,6価の化合物23種類についてやや詳しく述べた。ネプツニウムに関しては、5価及び6価の貯蔵液の調整法,3価の化合物4項目(6種類),4価の化合物8項目(19種類),5価の化合物28項目(29種類),6価の化合物10項目(14種類)及び7価の化合物5項目(9種類)についてやや詳しく述べた。 また、詳しく記述できなかった化合物については、第5章に化合物名を列挙し、参考文献を示した。ここで用いた資料は、ウラン及びネプツニウム化合物の物性を、主な研究手段としてメスバウア分光法を用いて調べる研究活動過程で集積したものである。そこで、最後にアクチノイドのメスバウア分光法に関する総説類を列挙した。
芳賀 芳範; 山本 悦嗣; 常盤 欣文; 青木 大*; 稲田 佳彦*; 摂待 力生*; 眞榮平 孝裕; 山上 浩志*; 播磨 尚朝*; 大貫 惇睦
Journal of Nuclear Science and Technology, 39(Suppl.3), p.56 - 62, 2002/11
ウラン化合物のフェルミ面をドハース・ファンアルフェン(dHvA)効果を用いて研究した。磁気秩序を持たない、遍歴5f物質USi, UC, UAl
の実験結果は、バンド理論で極めてよく説明できる。他方、伝導電子間の相関が強い重い電子系でもバンド理論が摘要可能であることがわかってきた。ただし、巨大な有効質量はバンド理論では説明できない。また、重い電子系超伝導体URu
Si
, UPd
Al
, CeRu
で、超伝導混合状態におけるdHvA振動の観測に成功し、有効質量及び散乱緩和時間の顕著な磁場依存性を観測した。