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論文

Quasifree neutron knockout reaction reveals a small $$s$$-Orbital component in the Borromean nucleus $$^{17}$$B

Yang, Z. H.*; 久保田 悠樹*; Corsi, A.*; 吉田 数貴; Sun, X.-X.*; Li, J. G.*; 木村 真明*; Michel, N.*; 緒方 一介*; Yuan, C. X.*; et al.

Physical Review Letters, 126(8), p.082501_1 - 082501_8, 2021/02

 被引用回数:10 パーセンタイル:98.7(Physics, Multidisciplinary)

ボロミアン核であり中性子ハロー構造が期待される$$^{17}$$Bに対する($$p$$,$$pn$$)反応実験を行った。断面積の運動量分布を分析することで、$$1s_{1/2}$$$$0d_{5/2}$$軌道の分光学的因子を決定した。驚くべきことに、$$1s_{1/2}$$の分光学的因子は9(2)%と小さいことが明らかになった。この結果は、連続状態を含むdeformed relativistic Hartree-Bogoliubov理論によってよく説明された。本研究の結果によると、現在知られているハロー構造を持つとされる原子核の中で$$^{17}$$Bは$$s$$および$$p$$軌道の成分が最も小さく、$$s$$または$$p$$軌道成分が支配的であることが必ずしもハロー構造の前提条件ではない可能性を示唆している。

論文

The Joint evaluated fission and fusion nuclear data library, JEFF-3.3

Plompen, A. J. M.*; Cabellos, O.*; De Saint Jean, C.*; Fleming, M.*; Algora, A.*; Angelone, M.*; Archier, P.*; Bauge, E.*; Bersillon, O.*; Blokhin, A.*; et al.

European Physical Journal A, 56(7), p.181_1 - 181_108, 2020/07

 被引用回数:73 パーセンタイル:99.41(Physics, Nuclear)

本論文では、核分裂と核融合のための統合評価済み核データファイルのバージョン3.3(JEFF-3.3)について説明する。中性子との反応が重要な核種の$$^{235}$$U, $$^{238}$$U, $$^{239}$$Pu, $$^{241}$$Am, $$^{23}$$Na, $$^{59}$$Ni, Cr, Cu, Zr, Cd, Hf, Au, Pb, Biについて、新しい核データ評価結果を示す。JEFF-3.3には、核分裂収率, 即発核分裂スペクトル, 核分裂平均中性子発生数の新しいデータが含まれる。更に、放射崩壊, 熱中性子散乱, ガンマ線放出, 中性子による放射化, 遅発中性子, 照射損傷に関する新しいデータも含まれている。JEFF-3.3は、TENDLプロジェクトのファイルで補完しており、光子, 陽子, 重陽子, 三重陽子, $$^{3}$$He核, アルファ粒子による反応ライブラリについては、TENDL-2017から採用した。また、不確かさの定量化に対する要求の高まりから、多くの共分散データが新しく追加された。JEFF-3.3を用いた解析の結果と臨界性, 遅発中性子割合, 遮蔽, 崩壊熱に対するベンチマーク実験の結果を比較することにより、JEFF-3.3は幅広い原子核技術の応用分野、特に原子力エネルギーの分野において優れた性能を持っていることが分かった。

論文

Clades of huge phages from across Earth's ecosystems

Al-Shayeb, B.*; Sachdeva, R.*; Chen, L.-X.*; Ward, F.*; Munk, P.*; Devoto, A.*; Castelle, C. J.*; Olm, M. R.*; Bouma-Gregson, K.*; 天野 由記; et al.

Nature, 578(7795), p.425 - 431, 2020/02

 被引用回数:83 パーセンタイル:99.63(Multidisciplinary Sciences)

Phage typically have small genomes and depend on their bacterial hosts for replication. We generated metagenomic datasets from many diverse ecosystems and reconstructed hundreds of huge phage genomes, between 200 kbp and 716 kbp in length. Thirty four genomes were manually curated to completion, including the largest phage genomes yet reported. Expanded genetic repertoires include diverse and new CRISPR-Cas systems, tRNAs, tRNA synthetases, tRNA modification enzymes, initiation and elongation factors and ribosomal proteins. Phage CRISPR have the capacity to silence host transcription factors and translational genes, potentially as part of a larger interaction network that intercepts translation to redirect biosynthesis to phage-encoded functions. Some phage repurpose bacterial systems for phage-defense to eliminate competing phage. We phylogenetically define seven major clades of huge phage from human and other animal microbiomes, oceans, lakes, sediments, soils and the built environment. We conclude that large gene inventories reflect a conserved biological strategy, observed across a broad bacterial host range and resulting in the distribution of huge phage across Earth's ecosystems.

論文

Fine structure in the $$alpha$$ decay of $$^{223}$$U

Sun, M. D.*; Liu, Z.*; Huang, T. H.*; Zhang, W. Q.*; Andreyev, A. N.; Ding, B.*; Wang, J. G.*; Liu, X. Y.*; Lu, H. Y.*; Hou, D. S.*; et al.

Physics Letters B, 800, p.135096_1 - 135096_5, 2020/01

 被引用回数:6 パーセンタイル:89.19(Astronomy & Astrophysics)

Fine structure in the $$alpha$$ decay of $$^{223}$$U was observed in the fusion-evaporation reaction $$^{187}$$Re($$^{40}$$Ar,p3n) by using fast digital pulse processing technique. Two $$alpha$$-decay branches of $$^{223}$$U feeding the ground state and 244 keV excited state of $$^{219}$$Th were identified by establishing the decay chain $$^{223}$$U$$rightarrow$$$$^{219}$$Th$$rightarrow$$$$^{215}$$Ra$$rightarrow$$$$^{211}$$Rn. The $$alpha$$-particle energy for the ground-state to ground-state transition of $$^{223}$$U was determined to be 8993(17) keV, 213 keV higher than the previous value, the half-life was updated to be 62$$^{+14}_{-10} mu$$s. Evolution of nuclear structure for $$N$$=131 even-$$Z$$ isotones from Po to U was discussed in the frameworks of nuclear mass and reduced $$alpha$$-decay width, a weakening octupole deformation in the ground state of $$^{223}$$U relative to its lighter isotones $$^{219}$$Ra and $$^{211}$$Th was suggested.

論文

Spin colossal magnetoresistance in an antiferromagnetic insulator

Qiu, Z.*; Hou, D.*; Barker, J.*; 山本 慧; Gomonay, O.*; 齊藤 英治*

Nature Materials, 17(7), p.577 - 580, 2018/05

 被引用回数:71 パーセンタイル:96.98(Chemistry, Physical)

巨大磁気抵抗とは導体絶縁体相転移の近傍で磁場により電気抵抗が大幅に変化する現象を指す。これは磁気構造と電気伝導の強い相関に由来し、数十年にわたって盛んに研究されてきた。本稿では、反強磁性絶縁体であるCr$$_{2}$$O$$_{3}$$が室温においてスピン流についての明確な導体不導体を起こすことを報告する。スピン流透過率はネール温度近傍の14度の間で2桁変化する。このスピン流についての導体不導体転移は磁場によって制御可能であり、定温で最大500%透過率が変化し事実上のスピン流透過不透過切り替えのスイッチとなる。

論文

Scaling of memories and crossover in glassy magnets

Samarakoon, A. M.*; 高橋 満*; Zhang, D.*; Yang, J.*; 片山 尚幸*; Sinclair, R.*; Zhou, H. D.*; Diallo, S. O.*; Ehlers, G.*; Tennant, D. A.*; et al.

Scientific Reports (Internet), 7(1), p.12053_1 - 12053_8, 2017/09

AA2017-0448.pdf:3.45MB

 被引用回数:4 パーセンタイル:44.41(Multidisciplinary Sciences)

Glassiness is ubiquitous and diverse in characteristics in nature. Understanding their differences and classification remains a major scientific challenge. Here, we show that scaling of magnetic memories with time can be used to classify magnetic glassy materials into two distinct classes. The systems studied are high temperature superconductor-related materials, spin-orbit Mott insulators, frustrated magnets, and dilute magnetic alloys. Our bulk magnetization measurements reveal that most densely populated magnets exhibit similar memory behavior characterized by a relaxation exponent of $$1-n$$ $$approx$$ $$0.6$$(1). This exponent is different from $$1-n$$ $$approx$$ $$1/3$$ of dilute magnetic alloys that was ascribed to their hierarchical and fractal energy landscape, and is also different from $$1-n=1$$ of the conventional Debye relaxation expected for a spin solid, a state with long range order.

論文

Antiferromagnetic anisotropy determination by spin Hall magnetoresistance

Wang, H.*; Hou, D.*; Qiu, Z.*; 吉川 貴史*; 齊藤 英治; Jin, X.*

Journal of Applied Physics, 122(8), p.083907_1 - 083907_6, 2017/08

 被引用回数:2 パーセンタイル:14.14(Physics, Applied)

An electric method for measuring magnetic anisotropy in antiferromagnetic insulators (AFIs) is proposed. When a metallic film with strong spin-orbit interactions, e.g., platinum (Pt), is deposited on an AFI, its resistance should be affected by the direction of the AFI N$'e$el vector due to the spin Hall magnetoresistance (SMR). Accordingly, the direction of the AFI N$'e$el vector, which is affected by both the external magnetic field and the magnetic anisotropy, is reflected in resistance of Pt. The magnetic field angle dependence of the resistance of Pt on AFI is calculated by considering the SMR, which indicates that the antiferromagnetic anisotropy can be obtained experimentally by monitoring the Pt resistance in strong magnetic fields. Calculations are performed for realistic systems such as Pt/Cr$$_2$$O$$_3$$, Pt/NiO, and Pt/CoO.

論文

Time-resolved study of field-induced suppression of longitudinal spin Seebeck effect

日置 友智*; 井口 亮*; Qiu, Z.*; Hou, D.*; 内田 健一*; 齊藤 英治

Applied Physics Express, 10(7), p.073002_1 - 073002_4, 2017/06

 被引用回数:9 パーセンタイル:53.89(Physics, Applied)

We have investigated the magnetic-field-induced suppression of the longitudinal spin Seebeck effect (LSSE) by using a time-resolved measurement technique at room temperature. The result manifested two distinctive time domains: the short-time domain where the observed voltage is insensitive to the magnetic fields, and the long-time domain where the both response time and the magnitude of the observed voltage decreased simultaneously by the magnetic fields. We estimated the magnon propagation length by fitting the transient LSSE response. The propagation length shows a strong dependence on the applied magnetic field, indicating the importance of long-range and low-frequency magnons in the LSSE.

論文

Tunable sign change of spin hall magnetoresistance in Pt/NiO/YIG structures

Hou, D.*; Qiu, Z.*; Barker, J.*; 佐藤 浩司*; 山本 慧; V$'e$lez, S.*; Gomez-Perez, J. M.*; Hueso, L. E.*; Casanova, F.*; 齊藤 英治

Physical Review Letters, 118(14), p.147202_1 - 147202_6, 2017/04

 被引用回数:85 パーセンタイル:98(Physics, Multidisciplinary)

Spin Hall magnetoresistance (SMR) has been investigated in Pt/NiO/YIG structures in a wide range of temperature and NiO thickness. The SMR shows a negative sign below a temperature that increases with the NiO thickness. This is contrary to a conventional SMR theory picture applied to the Pt/YIG bilayer, which always predicts a positive SMR. The negative SMR is found to persist even when NiO blocks the spin transmission between Pt and YIG, indicating it is governed by the spin current response of the NiO layer. We explain the negative SMR by the NiO "spin flop" coupled with YIG, which can be overridden at higher temperature by positive SMR contribution from YIG. This highlights the role of magnetic structure in antiferromagnets for transport of pure spin current in multilayers.

論文

Spin-current probe for phase transition in an insulator

Qiu, Z.*; Li, J.*; Hou, D.*; Arenholz, E.*; N'Diaye, A. T.*; Tan, A.*; 内田 健一*; 佐藤 浩司*; 岡本 聡*; Tserkovnyak, Y.*; et al.

Nature Communications (Internet), 7, p.12670_1 - 12670_6, 2016/08

 被引用回数:107 パーセンタイル:97.44(Multidisciplinary Sciences)

Spin fluctuation and transition have always been one of the central topics of magnetism and condensed matter science. Experimentally, the spin fluctuation is found transcribed onto scattering intensity in the neutron-scattering process, which is represented by dynamical magnetic susceptibility and maximized at phase transitions. Importantly, a neutron carries spin without electric charge, and therefore it can bring spin into a sample without being disturbed by electric energy. However, large facilities such as a nuclear reactor are necessary. Here we show that spin pumping, frequently used in nanoscale spintronic devices, provides a desktop microprobe for spin transition; spin current is a flux of spin without an electric charge and its transport reflects spin excitation. We demonstrate detection of antiferromagnetic transition in ultra-thin CoO films via frequency-dependent spin-current transmission measurements, which provides a versatile probe for phase transition in an electric manner in minute devices.

論文

Observation of temperature-gradient-induced magnetization

Hou, D.*; Qiu, Z.*; 井口 亮*; 佐藤 浩司*; Vehstedt, E. K.*; 内田 健一*; Bauer, G. E. W.*; 齊藤 英治

Nature Communications (Internet), 7, p.12265_1 - 12265_6, 2016/07

 被引用回数:10 パーセンタイル:65.26(Multidisciplinary Sciences)

Applying magnetic fields has been the method of choice to magnetize non-magnetic materials, but they are difficult to focus. The magneto-electric effect and voltage-induced magnetization generate magnetization by applied electric fields, but only in special compounds or heterostructures. Here we demonstrate that a simple metal such as gold can be magnetized by a temperature gradient or magnetic resonance when in contact with a magnetic insulator by observing an anomalous Hall-like effect, which directly proves the breakdown of time-reversal symmetry. Such Hall measurements give experimental access to the spectral spin Hall conductance of the host metal, which is closely related to other spin caloritronics phenomena such as the spin Nernst effect and serves as a reference for theoretical calculation.

論文

All-oxide spin Seebeck effects

Qiu, Z.*; Hou, D.*; 吉川 貴史*; 内田 健一*; 齊藤 英治

Applied Physics Express, 8(8), p.083001_1 - 083001_3, 2015/08

 被引用回数:23 パーセンタイル:74.03(Physics, Applied)

We report the observation of longitudinal spin Seebeck effects (LSSEs) in an all-oxide bilayer system comprising an IrO$$_2$$ film and an Y$$_3$$Fe$$_5$$O$$_{12}$$ film. Spin currents, which are generated by a temperature gradient across the IrO$$_2$$/Y$$_3$$Fe$$_5$$O$$_{12}$$ interface, were detected as a voltage via the inverse spin Hall effect in the conductive IrO$$_{2}$$ layer. This voltage is proportional to the magnitude of the temperature gradient; its magnetic field dependence is consistent with the characteristics of LSSEs. This demonstration may lead to the realization of low-cost, stable, transparent spin-current-driven thermoelectric devices.

論文

Intrinsic surface magnetic anisotropy in Y$$_{3}$$Fe$$_{5}$$O$$_{12}$$ as the origin of low-magnetic-field behavior of the spin Seebeck effect

内田 健一*; 大江 純一郎*; 吉川 貴史*; 大門 俊介*; Hou, D.*; Qiu, Z.*; 齊藤 英治

Physical Review B, 92(1), p.014415_1 - 014415_8, 2015/07

 被引用回数:26 パーセンタイル:77.37(Materials Science, Multidisciplinary)

The magnetic-field dependence of the longitudinal spin Seebeck effect (LSSE) in a Pt/Y$$_{3}$$Fe$$_{5}$$O$$_{12}$$ (YIG)-slab junction system was found to deviate from a bulk magnetization curve of the YIG slab in a low field range. In this paper, we show that the deviation originates from the difference between surface and bulk magnetization processes in the YIG slab and that it appears even when removing possible extrinsic magnetic anisotropy due to surface roughness and replacing the Pt layer with different materials. This result indicates that the anomalous field dependence of the LSSE is due to an intrinsic magnetic property of the YIG surface. Our numerical calculation based on the Landau-Lifshitz-Gilbert equation shows that the deviation between the LSSE and bulk magnetization curves is qualitatively explained by introducing easy-axis perpendicular magnetic anisotropy near the surface of YIG.

論文

Spin-current injection and detection in $$kappa$$-(BEDT-TTF)$$_{2}$$Cu[N(CN)$$_{2}$$]Br

Qiu, Z.*; 賣市 幹大*; Hou, D.*; 内田 健一*; 山本 浩史*; 齊藤 英治

AIP Advances (Internet), 5(5), p.057167_1 - 057167_7, 2015/05

 被引用回数:14 パーセンタイル:59.87(Nanoscience & Nanotechnology)

Spin-current injection into an organic semiconductor $$kappa$$-(BEDT-TTF)$$_{2}$$Cu[N(CN)$$_{2}$$]Br film induced by the spin pumping from an yttrium iron garnet (YIG) film. When magnetization dynamics in the YIG film is excited by ferromagnetic or spin-wave resonance, a voltage signal was found to appear in the $$kappa$$-(BEDT-TTF)$$_{2}$$Cu[N(CN)$$_{2}$$]Br film. Magnetic-field-angle dependence measurements indicate that the voltage signal is governed by the inverse spin Hall effect in $$kappa$$-(BEDT-TTF)$$_{2}$$Cu[N(CN)$$_{2}$$]Br. We found that the voltage signal in the $$kappa$$-(BEDT-TTF)$$_{2}$$Cu[N(CN)$$_{2}$$]Br/YIG system is critically suppressed around 80 K, around which magnetic and/or glass transitions occur, implying that the efficiency of the spin-current injection is suppressed by fluctuations which critically enhanced near the transitions.

論文

Influence of interface condition on spin-Seebeck effects

Qiu, Z.*; Hou, D.*; 内田 健一*; 齊藤 英治

Journal of Physics D; Applied Physics, 48(16), p.164013_1 - 164013_5, 2015/04

 被引用回数:35 パーセンタイル:84.67(Physics, Applied)

The longitudinal spin-Seebeck effect (LSSE) has been investigated for Pt/yttrium iron garnet (YIG) bilayer systems. The magnitude of the voltage induced by the LSSE is found to be sensitive to the Pt/YIG interface condition. We observed large LSSE voltage in a Pt/YIG system with a better crystalline interface, while the voltage decays steeply when an amorphous layer is introduced at the interface artificially.

論文

Active sites and mechanisms for oxygen reduction reaction on nitrogen-doped carbon alloy catalysts; Stone-Wales defect and curvature effect

Chai, G.-L.*; Hou, Z.*; Shu, D.-J.*; 池田 隆司; 寺倉 清之*

Journal of the American Chemical Society, 136(39), p.13629 - 13640, 2014/10

 被引用回数:198 パーセンタイル:97.69(Chemistry, Multidisciplinary)

カーボンアロイ触媒は酸素還元反応の白金代替触媒として有望視されている。しかしながら酸素還元反応の反応サイトと反応機構についてはまだ議論されているところである。本論文では、第一原理計算に基づいて窒素ドープカーボンアロイ触媒中の様々な構造による可能な酸素還元反応機構に関して一般的な考察を行った。我々の研究から、Stone-Wales欠陥にドープされた窒素対のみが良い活性点を与えることが示唆され、この構造による酸素還元活性は活性点周囲の曲率により調整ができ、極大ポテンシャル(0.8V)に近づけることが可能であることが示された。

論文

Interplay between oxidized monovacancy and nitrogen doping in graphene

Hou, Z.*; Shu, D.-J.*; Chai, G.-L.*; 池田 隆司; 寺倉 清之*

Journal of Physical Chemistry C, 118(34), p.19795 - 19805, 2014/08

 被引用回数:10 パーセンタイル:38.87(Chemistry, Physical)

非貴金属触媒やナノ電子デバイス材料として注目されている窒素ドープグラフェンには、多くの場合、窒素量と同程度かそれ以上の酸素が含まれている。我々は、グラフェンの単空孔は複空孔やストーンウェルズ欠陥よりもしばしば観察され、より化学的に活性であることから、酸化単空孔と窒素ドーパントの相互作用を密度汎関数計算により調べた。温度と酸素、水素ガスの分圧の関数として窒素未ドープ酸化単空孔と窒素ドープ酸化単空孔の相図を求めた。また単空孔の酸化と窒素ドープによる電子構造の変化を調べた。我々の計算結果からエーテル基が酸化単空孔での安定構造に共通して存在し、ほとんどの安定構造ではキャリアがドープされないことがわかった。

論文

In-beam $$gamma$$ spectroscopy of the even-even nucleus $$^{190}$$Pt

Li, G. S.*; Liu, M. L.*; Zhou, X. H.*; Zhang, Y. H.*; Liu, Y. X.*; Zhang, N. T.*; Hua, W.*; Zheng, Y. D.*; Fang, Y. D.*; Guo, S.*; et al.

Physical Review C, 89(5), p.054303_1 - 054303_9, 2014/05

 被引用回数:5 パーセンタイル:42.25(Physics, Nuclear)

タンデム加速器で88MeVにまで加速された$$^{18}$$Oビームを用いて$$^{176}$$Yb($$^{18}$$O, 4$$n$$)反応を起こし、$$^{190}$$Ptの高スピン準位を調べた。その結果、$$nu$$ $$i^{-2}_{13/2}$$ $$nu$$ $$h^{-1}_{9/2}$$ $$nu$$ $$j^{-1}$$1(ここで$$nu j$$$$nu p_{3/2}$$もしくは$$nu f_{5/2}$$)配位による正パリティバンドを大幅に拡張するとともに新しく負パリティバンドを同定し、$$nu$$ $$i^{-3}_{13/2}$$ $$nu$$ $$j^{-1}$$配位を持つことを明らかにした。また、イラスト準位においてスピンの増加に伴い振動から回転へと構造変化を起こしている可能性について議論した。さらにバンド特性を明らかにするためにTotal Routhian surface計算を行った。

論文

Separation of longitudinal spin Seebeck effect from anomalous Nernst effect; Determination of origin of transverse thermoelectric voltage in metal/insulator junctions

吉川 貴史*; 内田 健一*; 大門 俊介*; 塩見 雄毅*; 安立 裕人; Qiu, Z.*; Hou, D.*; Jin, X.-F.*; 前川 禎通; 齊藤 英治

Physical Review B, 88(21), p.214403_1 - 214403_11, 2013/12

 被引用回数:103 パーセンタイル:96.28(Materials Science, Multidisciplinary)

The longitudinal spin Seebeck effect and the anomalous Nernst effect are investigated in various metal/insulator junction systems, and the clear separation of the longitudinal spin Seebeck effect from the anomalous Nernst effect induced by static magnetic proximity is demonstrated. It is shown that, in Pt/Y$$_{3}$$Fe$$_{5}$$O$$_{12}$$ samples, the longitudinal spin Seebeck effect is three orders of magnitude greater than the proximity-driven anomalous Nernst effect.

論文

Experimental investigation of spin Hall effect in indium tin oxide thin film

Qiu, Z.*; 安 東秀*; 内田 健一*; Hou, D.*; 塩見 雄毅*; 藤川 安仁*; 齊藤 英治

Applied Physics Letters, 103(18), p.182404_1 - 182404_3, 2013/10

 被引用回数:15 パーセンタイル:59.37(Physics, Applied)

The inverse spin Hall effect (ISHE) induced by spin pumping in indium tin oxide (ITO) films has been investigated quantitatively. We measured ferromagnetic resonance and electromotive force spectra with changing the ITO thickness in ITO/permalloy bilayer films. The intensity of the observed electromotive force changes systematically with the ITO film thickness, which is consistent with the prediction of ISHE. By using an equivalent circuit model, the spin Hall angle and diffusion length of the ITO film are estimated.

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