検索対象:     
報告書番号:
※ 半角英数字
 年 ~ 
 年
検索結果: 85 件中 1件目~20件目を表示

発表形式

Initialising ...

選択項目を絞り込む

掲載資料名

Initialising ...

発表会議名

Initialising ...

筆頭著者名

Initialising ...

キーワード

Initialising ...

使用言語

Initialising ...

発行年

Initialising ...

開催年

Initialising ...

選択した検索結果をダウンロード

論文

Crystallographic, magnetic, thermal, and electric transport properties in UPtIn single crystal

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

 パーセンタイル:100(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 $$T$$-linear behavior, indicating the smaller electronic specific heat than the previous study.

論文

Atomic-scale visualization of surface-assisted orbital order

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

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$$_5$$. 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.

論文

Magnetoresistance and Hall effect of antiferromagnetic uranium compound URhIn$$_5$$

芳賀 芳範; 松本 裕司*; Pospisil, J.; 立岩 尚之; 山本 悦嗣; 山村 朝雄*; Fisk, Z.*

Journal of Physics; Conference Series, 807(1), p.012015_1 - 012015_4, 2017/04

Transport characteristics of an antiferromagnetic uranium compound URhIn$$_5$$ are studied. The antiferromagnetic transition leads to a formation of a gap on the Fermi surface as demonstrated by a hump in the resistivity behavior as a function of temperature. Hall effect, magnetoresistance and de Haas-van Alphen study consistently demonstrate a small carrier concentration in the antiferromagnetic state suggesting that majority of the Fermi surface vanishes.

論文

Fermi surface of ThRu$$_{2}$$Si$$_{2}$$ as a reference to the strongly correlated isostructural metals investigated by quantum oscillations

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:2 パーセンタイル:63.85(Physics, Multidisciplinary)

dHvA oscillations were detected on an actinide compound ThRu$$_2$$Si$$_2$$ which is regarded as a reference to strongly correlated electron systems URu$$_2$$Si$$_2$$ and CeRu$$_2$$Si$$_2$$. Observed Fermi surfaces well coincides with the band structure calculations, as well as experimentally obtained ones for a heavy fermion compound CeRu$$_2$$Si$$_2$$. On the other hand, Fermi surfaces of URu$$_2$$Si$$_2$$ have significantly different characteristics, suggesting an itinerant ground state of 5f electrons.

論文

Magnetic and electronic properties of URu$$_2$$Si$$_2$$ revealed by comparison with nonmagnetic references ThRu$$_2$$Si$$_2$$ and LaRu$$_2$$Si$$_2$$

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:9 パーセンタイル:31.29(Physics, Multidisciplinary)

NMR/NQR measurements have been carried out on ThRu$$_2$$Si$$_2$$ and LaRu$$_2$$Si$$_2$$ which are the nonmagnetic references of the heavy fermion URu$$_2$$Si$$_2$$. Ru-NQR measurements suggest the relatively close electronic configuration between ThRu$$_2$$Si$$_2$$ and URu$$_2$$Si$$_2$$ at high temperature. However, significant delocalization was observed in URu$$_2$$Si$$_2$$ at low temperatures. Si-NMR experiments on URu$$_2$$Si$$_2$$ revealed Ising-like spin fluctuations in the hidden-order state.

論文

Enhancement of the cyclotron effective mass in U$$_{0.03}$$Th$$_{0.97}$$Ru$$_2$$Si$$_2$$

芳賀 芳範; 松本 裕司*; 立岩 尚之; 山本 悦嗣; 木村 憲彰*; 山村 朝雄*; Fisk, Z.

Journal of Physics; Conference Series, 592(1), p.012036_1 - 012036_5, 2015/03

 被引用回数:2 パーセンタイル:24.39

We investigate the modification of the electronic state of ThRu$$_2$$Si$$_2$$ upon replacing non magnetic Th by U. We successfully observed the quantum oscillation signals from the Fermi surface. The observed Fermi surfaces did not show a significant change in size for the U$$_{0.03}$$Th$$_{0.97}$$Ru$$_2$$Si$$_2$$ sample. However the enhancement of the cyclotron effective mass demonstrates the hybridization of the 5$$f$$ states with the conduction bands.

論文

Single crystal growth and characterization of URu$$_2$$Si$$_2$$

芳賀 芳範; 松田 達磨*; 立岩 尚之; 山本 悦嗣; 大貫 惇睦; Fisk, Z.

Philosophical Magazine, 94(32-33), p.3672 - 3680, 2014/11

 被引用回数:5 パーセンタイル:55.58(Materials Science, Multidisciplinary)

We review recent progress in single crystal growth and study of electronic properties in URu$$_2$$Si$$_2$$. Czocharalski pulling, using purified uranium metal and subsequent annealing under ultra-high vacuum, is successfully applied to this compound, and it yields the highest residual resistivity ratio. These high-quality single crystals allow us to investigate Fermi surfaces using quantum oscillation and to make detailed transport measurements at low temperature.

論文

Electronic states in antiferromagnetic compound URhIn$$_5$$ investigated by de Haas-van Alphen effect and high pressure resistivity measurements

松本 裕司; 芳賀 芳範; 立岩 尚之; 山本 悦嗣; 木村 憲彰*; 青木 晴善*; Fisk, Z.

JPS Conference Proceedings (Internet), 3, p.011097_1 - 011097_5, 2014/06

Single crystal samples of a new uranium compound URhIn$$_5$$ with the well-known tetragonal HoCoGa$$_5$$-type structure have been grown by the indium flux method. Although this compound is isostructural to a Ga-analogue URhGa$$_5$$, the unit cell volume is significantly larger in URhIn$$_5$$. In contrast to non-magnetic behavior in the isostructural URhGa$$_5$$, URhIn$$_5$$ has a magnetic ground state with a magnetic transition at 98 K, indicating a drastic difference in electronic states between these compounds.

論文

Drastic change in ferromagnetic ground state associated with pressure-induced metal-insulator transition in $$beta$$-US$$_2$$

立岩 尚之; 芳賀 芳範; 山本 悦嗣; Fisk, Z.

JPS Conference Proceedings (Internet), 3, p.011086_1 - 011086_7, 2014/06

$$beta$$-US$$_2$$は常圧で非磁性の半導体である。圧力を加えると、0.5GPaで非常に弱い強磁性状態が誘起される。この強磁性状態は「誘起磁性」状態と理解される。本研究では、$$beta$$-US$$_2$$の高圧下磁化測定を絶縁体金属転移する5GPaを越え行った。金属状態へと転移すると、自発磁化の値は、0.04から0.4$${mu}_{rm B}$$/Uへと増大する。強磁性状態は、伝導キャリアの増大とともに安定化すると思われる。

論文

Analysis of magnetization behavior in magnetic semiconductor $$beta$$-US$$_{2}$$

山本 悦嗣; 立岩 尚之; 芳賀 芳範; 池田 修悟*; 酒井 宏典; 大貫 惇睦; Fisk, Z.

JPS Conference Proceedings (Internet), 3, p.011095_1 - 011095_4, 2014/06

$$beta$$-US$$_2$$ is a paramagnetic semiconductor. Chemical substitution of the sulfur site or application of hydrostatic pressure induces ferromagnetic ordering, indicating that $$beta$$-US$$_2$$ is located near the ferromagnetic instability. Application of magnetic field leads to a huge negative magnetoresistance in $$beta$$-US$$_2$$ and this behavior is discussed based on the magnetic polaron. In the present study, we study the magnetic, transport and thermal properties of $$beta$$-US$$_2$$ in detail to clarify the anomalous behavior. Magnetization measurements at low temperature can roughly be explained by a ferromagnetic cluster behavior where the number of the cluster is equal to the number of carrier estimated from Hall effect measurements, consistent with the magnetic polaron model.

論文

Single-crystal growth and de Haas-van Alphen effect study of ThRu$$_2$$Si$$_2$$

松本 裕司*; 芳賀 芳範; 立岩 尚之; 青木 晴善*; 木村 憲彰*; 松田 達磨*; 山本 悦嗣; Fisk, Z.; 山上 浩志*

JPS Conference Proceedings (Internet), 3, p.011096_1 - 011096_5, 2014/06

Electronic differences between heavy Fermion CeRu$$_2$$Si$$_2$$ and isoelectronic nonmagnetic ThRu$$_2$$Si$$_2$$ have been investigated. We succeeded in observing the de Haas-van Alphen oscillation in a high quality single crystal of ThRu$$_2$$Si$$_2$$. The mean free path of conduction carriers has been estimated as 6400 ${AA}$, indicating the high quality of the present sample.

論文

High pressure magnetic measurements on strongly correlated electron systems with a miniature ceramic anvil high pressure cell

立岩 尚之; 芳賀 芳範; 松田 達磨*; Fisk, Z.

Journal of Physics; Conference Series, 500(14), p.142032_1 - 142032_5, 2014/05

 被引用回数:1 パーセンタイル:37.67

高圧下磁化測定を目的としたセラミックアンビルセル(mCAC)の開発を進めてきた。SQUID磁束計と組合せることで、12GPaまでの直流磁化測定が可能となった。本国際会議ではmCACの仕様と、最近の開発結果を紹介する。さらに、希土類化合物YbCu$$_2$$Si$$_2$$の実験結果も紹介する。YbCu$$_2$$Si$$_2$$は常圧では常磁性化合物であるが、8GPa以上で圧力誘起型の強磁性秩序が誘起されることが交流磁化率・比熱測定から示唆された。mCACを用いた測定から、圧力誘起秩序相の強磁性成分の存在を直流磁化測定から確認した。さらに、単結晶試料を用いて磁気異方性について調査し、圧力誘起磁気秩序相が、非常に強い一軸磁気異方性を持つことを明らかにした。

論文

Unconventional critical scaling of magnetization in ferromagnetic uranium superconductors UGe$$_2$$ and URhGe

立岩 尚之; 芳賀 芳範; 松田 達磨*; 山本 悦嗣; Fisk, Z.

Physical Review B, 89(6), p.064420_1 - 064420_8, 2014/02

 被引用回数:17 パーセンタイル:24.61(Materials Science, Multidisciplinary)

ウラン系強磁性超伝導物質UGe$$_2$$、URhGeの強磁性転移に伴う臨界現象を研究した。磁化に関する臨界指数$$beta$$$$delta$$は三次元磁性体から期待される値に近いが、磁化率の臨界指数$$gamma$$は、むしろ平均場理論から期待される値となった。ウラン系強磁性超伝導物質UGe$$_2$$, URhGeの臨界現象はこれまで報告されていない新しいタイプである。

論文

Pressure-induced ferromagnetism with strong Ising-type anisotropy in YbCu$$_2$$Si$$_2$$

立岩 尚之; 松田 達磨*; 芳賀 芳範; Fisk, Z.

Physical Review B, 89(3), p.035127_1 - 035127_5, 2014/01

 被引用回数:10 パーセンタイル:49.27(Materials Science, Multidisciplinary)

YbCu$$_2$$Si$$_2$$について、小型セラミックアンビルセルで行った、10GPaを越える超高圧領域における直流磁化測定の結果を報告する。YbCu$$_2$$Si$$_2$$は8GPaで圧力誘起非磁性-磁性転移が起きる。我々は9.4GPa以上で、自発磁化の存在を確認した。さらに磁気転移温度と2.0Kにおける自発磁化の圧力依存を決定した。圧力誘起相は強いイジング型一軸磁気異方性を持つことが明らかにされた。

論文

Magnetic phase diagram of UCoAl

松田 達磨; 立岩 尚之; 山本 悦嗣; 芳賀 芳範; 大貫 惇睦; 青木 大*; Flouquet, J.*; Fisk, Z.

Journal of the Korean Physical Society, 63(3), p.575 - 578, 2013/08

 被引用回数:4 パーセンタイル:57.4(Physics, Multidisciplinary)

Heavy fermion UCoAl is known to be a unique system with metamagnetic transition from paramagnetic to ferromagnetic ground state in uranium-based compounds. These kinds of metamagnetism and quantum criticality in strongly correlated electron systems have attracted much attention because of expectation of new quantum phases. Recently, we succeeded to grow a high quality single crystal of UCoAl by the Czochralski pulling method and performed the magnetic measurements. We present the magnetic phase diagram of UCoAl in detail.

論文

Magnetic property in the ferromagnetic superconductor UGe$$_2$$ at pressures above the ferromagnetic critical pressure

立岩 尚之; 芳賀 芳範; 松田 達磨; 山本 悦嗣; 大貫 惇睦; Fisk, Z.

Journal of the Korean Physical Society, 63(3), p.627 - 631, 2013/08

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

UGe$$_2$$は磁気転移温度54Kの強磁性物質であり、1.0-1.6GPaの強磁性相で超伝導が出現する。1.6GPa以上で強磁性状態が消滅する。本研究では、セラミックアンビルセルを用いた高圧下磁化測定を4.1GPaまで行った。常磁性状態の高圧領域では、磁化率の温度依存に温度$$T_{max}$$近辺で大きな極大が形成されることが明らかにされた。$$T_{max}$$は1.9GPaでは24Kである。加圧とともに増大し、2.6GPaでは32Kとなる。さらに1.6GPa以上の常磁性状態では、磁場を加えるとメタ磁性転移も現れ、その転移磁場$$H_m$$は加圧とともに増大してゆく。これらの現象をスピンの揺らぎ理論を用いて解析した。

論文

Shubnikov-de Haas oscillation in PuIn$$_3$$

芳賀 芳範; Bauer, E. D.*; Tobash, P. H.*; Mitchell, J. N.*; Ayala-Valenzuela, O.*; McDonald, R. D.*; Mielke, C. H.*; Fisk, Z.

Journal of the Korean Physical Society, 63(3), p.380 - 382, 2013/08

 被引用回数:2 パーセンタイル:73.65(Physics, Multidisciplinary)

Fermi surface of PuIn$$_3$$ is investigated using a flux-grown single crystals. Shubnikov-de Haas (SdH) oscillations were detected by means of the skin-depth measurement using a proximity-detector- oscillator circuit. Angular dependence of the SdH frequency which corresponds to the extremal cross-sectional area of Fermi surface agrees well with the previous magnetic susceptibility measurement using conventional field-modulation method. The SdH oscillation suddenly vanishes when the magnetic field is tilted from the cubic [111] direction.

論文

Single crystal growth and physical properties of UT$$_2$$Al$$_{20}$$ (T = transition metal)

松本 裕司; 松田 達磨; 立岩 尚之; 山本 悦嗣; 芳賀 芳範; Fisk, Z.

Journal of the Korean Physical Society, 63(3), p.363 - 366, 2013/08

 被引用回数:6 パーセンタイル:46.59(Physics, Multidisciplinary)

We have studied single crystal growth and physical properties of the UT$$_2$$Al$$_{20}$$ system. We have successfully grown UT$$_2$$Al$$_{20}$$ (T = Cr, Ti, W and Mo) using Al self flux and characterized the crystals using electron probe microanalyzer (EPAM) and X-ray diffraction, and measured their magnetic and electric properties. The ground states of UT$$_2$$Al$$_{20}$$ (T = Cr, Mo and W) are Pauli paramagnetic as is likely also in UTi$$_2$$Al$$_{20}$$. The effective masses of UCr$$_2$$Al$$_{20}$$ and UTi$$_2$$Al$$_{20}$$ are only weakly enhanced.

論文

Heavy fermion superconductivity; 5f vs 4f

Fisk, Z.; 芳賀 芳範

Journal of the Korean Physical Society, 63(3), p.795 - 799, 2013/08

 被引用回数:1 パーセンタイル:84.55(Physics, Multidisciplinary)

Heavy electron materials are the only class of materials in which we know where to look for superconductivity. We discuss the relation between single ion and dense Kondo heavy electron physics, what sets the energy scale in these materials, the ways in which their low temperature exotic superconductivity is a prototype for all highly correlated electron superconductivity and the similarities between the 4f and 5f heavy Fermion materials.

論文

Pressure evolution of the metamagnetic transition in UCoAl As measured using $$^{59}$$Co NMR

小手川 恒*; 野原 弘貴*; 藤 秀樹*; 松田 達磨; 山本 悦嗣; 芳賀 芳範; Fisk, Z.; 大貫 惇睦; 青木 大*; Flouquet, J.*

Journal of the Korean Physical Society, 63(3), p.341 - 344, 2013/08

 被引用回数:1 パーセンタイル:84.55(Physics, Multidisciplinary)

NMR measurements under pressure were preformed on the quantum critical endpoint (QCEP) of the metamagnetic transition in UCoAl. $$^{59}$$Co-NMR sensitively detects the evolution of the internal field caused by applying the external field. The loss of the NMR signal on approaching the QCEP indicates the development of spin fluctuations.

85 件中 1件目~20件目を表示