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Pu nuclear magnetic resonance in the candidate topological insulator PuB
Dioguardi, A. P.*; 安岡 弘志*; Thomas, S. M.*; 酒井 宏典; Cary, S. K.*; Kozimor, S. A.*; Albrecht-Schmitt, T. E.*; Choi, H. C.*; Zhu, J.-X.*; Thompson, J. D.*; et al.
Physical Review B, 99(3), p.035104_1 - 035104_6, 2019/01
被引用回数：12 パーセンタイル：44.22(Materials Science, Multidisciplinary)正方晶プルトニウムボロン化合物PuB
の単結晶、および粉末試料を用いて、Pu核核磁気共鳴(NMR)実験を行なった。この化合物は、最近になって強相関電子系のトポロジカル絶縁体候補物質と考えられている。Pu核NMRスペクトルは、結晶内Pu位置の局所対称性を反映したものとなっており、NMRシフトとNMR緩和率の温度依存性は、エネルギーギャップをもつ非磁性状態にあることが示唆された。これは、密度汎関数理論計算結果とも矛盾しない。実際に観測された巨視的なギャップ状態は、本化合物がトポロジカル絶縁体候補であることを支持している。
Gepr
gs, S.*; Kehlberger, A.*; Coletta, F.*; Qiu, Z.*; Guo, E.-J.*; Schulz, T.*; Mix, C.*; Meyer, S.*; Kamra, A.*; Althammer, M.*; et al.
Nature Communications (Internet), 7, p.10452_1 - 10452_6, 2016/02
被引用回数：191 パーセンタイル：97.51(Multidisciplinary Sciences)Magnons are the elementary excitations of a magnetically ordered system. Here, we show that the spin Seebeck effect is sensitive to the complexities of the magnon spectrum. The spin Seebeck effect is caused by a thermally excited spin dynamics that is converted to a voltage by the inverse spin Hall effect at the interface to a heavy metal contact. By investigating the temperature dependence of the spin Seebeck effect in the ferrimagnet gadlinium iron garnet, with a magnetic compensation point near room temperature, we demonstrate that high-energy exchange magnons play a key role in the spin Seebeck effect.
factor of the first excited 
state in 
ZnIllana, A.*; Jungclaus, A.*; Orlandi, R.; Perea, A.*; Bauer, C.*; Briz, J. A.*; Egido, J. L.*; Gernhuser, R.*; Leske, J.*; M
cher, D.*; et al.
Physical Review C, 89(5), p.054316_1 - 054316_11, 2014/05
被引用回数：11 パーセンタイル：56.48(Physics, Nuclear)The factor of the first excited state in Zn was measured using the transient-field technique in combination with Coulomb excitation. The experiment was ran at REX-ISOLDE, CERN, and the 
-ray perturbed angular correlations were measured using 4 triple Germanium clusters of the Miniball array. The experimental result (2
) = +0.47(14) is significant to establish the structure of the Zn isotopes near N=40. Comparison with shell-model calculations reveal that to reproduce the measured energies and B(E2) of the Zn isotopes around N=40, both the proton excitations from the 
orbit and neutron excitations into the 
and 
orbits are essential. Furthermore, beyond-mean-field calculations reveal the need to include the triaxial degree of freedom.
Althammer, M.*; Meyer, S.*; 中山 裕康*; Schreier, M.*; Altmannshofer, S.*; Weiler, M.*; Huebl, H.*; Geprgs, S.*; Opel, M.*; Gross, R.*; et al.
Physical Review B, 87(22), p.224401_1 - 224401_15, 2013/06
被引用回数：480 パーセンタイル：99.41(Materials Science, Multidisciplinary)強磁性絶縁体/Ptと強磁性絶縁体/常磁性金属/Pt複合素子において、スピンHall磁気抵抗効果の定量測定を行った。強磁性絶縁体にはイットリウム鉄ガーネット,ニッケルフェライト,マグネタイトを用い、常磁性中間層には銅、金を用いた。以上により、薄い中間層にかかわらず、Pt層のスピンHall効果と逆スピンHall効果の複合によって強磁性層の磁化方向に依存した磁気抵抗効果が生じるというスピンHall磁気抵抗効果の理論の正当性が実験的に確認された。スピンHall磁気抵抗効果の理論を援用することで、4
m
のスピンミキシングコンダクタンスを持つサンプルに対して、PtのスピンHall角とスピン拡散長がそれぞれ、
nmと得られた。
experiments on the flow and freezing of metal fuel and cladding melts, 2; Results, analysis, and applicationsWright, A. E.*; Bauer, T. H.*; Kilsdonk, D. J.*; Aeschlimann, R. W.*; 深野 義隆; 川田 賢一; 佐藤 一憲
Proceedings of International Conference on Fast Reactors and Related Fuel Cycles (FR 2009) (CD-ROM), 9 Pages, 2012/00
The Core Alloy Flow and Erosion (CAF) experiments have measured fundamental flow, metallurgical interaction, and freezing behavior of uranium and uranium-iron melts within iron-based trough-shaped flow channels relevant to phenomena that might occur in a hypothetical severe accident in a metal fueled fast reactor. CAF simulations conducted so far have engineered interactions of fuel and structural materials over a prototypic range of accident-related melt compositions and temperatures. Real-time measurements included flow-channel temperatures and video recording of the flowing melt. Post-test evaluations compare and contrast flow behaviors, trough damage, and debris distribution and indicate that thermo-chemical interactions play a central role in the interaction of molten fuel debris flowing on cold structure and may inhibit bulk freezing of the debris on the structure.
experiments on the flow and freezing of metal fuel and cladding melts, 1; Test conditions and overview of the results深野 義隆; 川田 賢一; 佐藤 一憲; Wright, A. E.*; Kilsdonk, D. J.*; Aeschlimann, R. W.*; Bauer, T. H.*
Proceedings of International Conference on Fast Reactors and Related Fuel Cycles (FR 2009) (CD-ROM), 10 Pages, 2012/00
For metal fueled fast reactors, assessment of the core disruptive accident (CDA) is necessary for both design and licensing. The objectives of the Core Alloy Flow and Erosion (CAF) experiments are to investigate the fundamental flow, metallurgical interaction, and freezing behavior of uranium-iron-type melts within iron-based trough-shaped flow channels and provide information that can support the development of mathematical models that describe the movements of molten fuel-bearing core materials during CDAs. In the CAFE experiments, melt produced in yttria-coated crucible by induction heating flowed down within approximately 660 mm long inclined trough and was received by the catch cup located below the bottom of the trough. Flow was observed and recorded by three video cameras and many thermocouples. Four UT series tests were conducted using molten uranium whose melting point is 1400 K. Two E1T series tests were performed using U-Fe eutectic mixture whose melting point is 1000 K. In each test, 1 to 1.65 kg of melt was introduced into an inclined trough. These test results provide understandings on fundamental flow and freezing behavior of melts including metallurgical interaction in the steel flow channels with a variety of melt and flow channel conditions and also offer useful information for developing analytical models to describe such behavior.
BiNi; A 
Bi NMR/NQR studyBaek, S.-H.*; Curro, N. J.*; Klimczuk, T.*; 酒井 宏典; Bauer, E. D.*; Ronning, F.*; Thompson, J. D.*
Physical Review B, 79(19), p.195120_1 - 195120_4, 2009/05
被引用回数：7 パーセンタイル：31.37(Materials Science, Multidisciplinary)We report Bi nuclear-magnetic-resonance and nuclear-quadrupole-resonance measurements on a single crystal of the Kondo insulator UBiNi. The Bi nuclear-spin-lattice relaxation rate (
) shows activated behavior and is well fit by a spin gap of 220 K. The Bi Knight shift (
) exhibits a strong temperature dependence arising from 
electrons, in which is negative at high temperatures and increases as the temperature is lowered. Below 50 K, shows a broad maximum and decreases slightly upon further cooling. Our data provide insight into the evolution of the hyperfine fields in a fully gapped Kondo insulator based on electron hybridization.
PRonning, F.*; Bauer, E. D.*; Park, T.*; Baek, S.-H.*; 酒井 宏典; Thompson, J. D.*
Physical Review B, 79(13), p.134507_1 - 134507_7, 2009/04
被引用回数：78 パーセンタイル：90.13(Materials Science, Multidisciplinary)Heat capacity, magnetic susceptibility, NMR, and resistivity of SrNiP single crystals are presented, illustrating a purely structural transition at 325 K with no magnetism. Bulk superconductivity is found at 1.4 K. The magnitude of the transition temperature 
, fits to the heat-capacity data, the small upper critical field 
=390 Oe, and Ginzburg-Landau parameter 
=2.1 suggest a conventional fully gapped superconductor. With applied pressure a second structural phase transition occurs which results in an 8% reduction in the 
ratio of lattice parameters. We find that superconductivity persists into this high-pressure phase, although the transition temperature is monotonically suppressed with increasing pressure. Comparison of these Ni-P data as well as layered Fe-As and Ni-As superconductor indicates that reduced dimensionality can be a mechanism for increasing the transition temperature.
中島 宏; 高田 弘; 春日井 好己; 明午 伸一郎; 前川 藤夫; 甲斐 哲也; 今野 力; 池田 裕二郎; 大山 幸夫; 渡辺 昇; et al.
Proceedings of 6th Meeting of the Task Force on Shielding Aspects of Accelerators, Targets and Irradiation Facilities (SATIF-6), (OECD/NEA No.3828), p.27 - 36, 2004/00
米国ブルックヘブン国立研究所AGS(Alternating Gradient Synchrotron)加速器を用いて行われている一連の核破砕ターゲット実験及びその解析の概要について報告する。本実験では、中性子発生特性,遮蔽設計パラメータに関する情報を得ることを目的として、AGS加速器から得られる数GeV,数百kJの陽子ビームを水銀核破砕ターゲットに入射し、そこで発生する二次粒子を用いて、中性子工学及び遮蔽に関する実験を過去4年間にわたって行ってきた。昨年、遮蔽実験を行うとともに、これまでの実験結果の解析を通して大強度陽子加速器施設の設計コードの精度検証が精力的に行われている。本報告では、昨年行った遮蔽実験の最新結果及びこれまで行ってきた実験解析の結果について紹介する。
中島 宏; 高田 弘; 春日井 好己; 明午 伸一郎; 前川 藤夫; 甲斐 哲也; 今野 力; 池田 裕二郎; 大山 幸夫; 渡辺 昇; et al.
Journal of Nuclear Science and Technology, 39(Suppl.2), p.1155 - 1160, 2002/08
次世代の数MW級核破砕中性子源の開発を目的として、日米欧の国際協力の下、米国ブルックヘブン国立研究所においてAGS(Alternating Gradient Synchrotron)加速器を用いた一連の実験が行われている。実験では、AGS加速器から得られる数GeV,数百kJの陽子ビームを水銀核破砕ターゲットに入射して、中性子源開発における重要な課題である、圧力波発生機構,中性子発生特性,遮蔽設計パラメーターに関する情報を得るため、圧力波測定,発熱分布測定など熱工学的実験並びに、発生中性子分布,エネルギースペクトル測定,遮蔽体内中性子減衰特性測定,核破砕生成物測定等,中性子工学実験及び遮蔽実験を行っている。ここでは、中性子工学実験及び遮蔽実験に関してこれまでに得られた成果など研究の現状について紹介する。
