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論文

Probing deformation behavior of a refractory high-entropy alloy using ${it in situ}$ neutron diffraction

Zhou, Y.*; Song, W.*; Zhang, F.*; Wu, Y.*; Lei, Z.*; Jiao, M.*; Zhang, X.*; Dong, J.*; Zhang, Y.*; Yang, M.*; et al.

Journal of Alloys and Compounds, 971, p.172635_1 - 172635_7, 2024/01

https://doi.org/10.1016/j.jallcom.2023.172635
 被引用回数：0 パーセンタイル：0(Chemistry, Physical)

The grain orientation-dependent lattice strain evolution of a (TiZrHfNb)$$_{98}$$$$N_2$$ refractory high-entropy alloy (HEA) during tensile loading has been investigated using ${it in situ}$ neutron diffraction. The equivalent strain-hardening rate of each of the primary $$<hkl>$$-oriented grain families was found to be relatively low, manifesting the macroscopically weak work-hardening ability of such a body-centered cubic (BCC)-structured HEA. This finding is indicative of a dislocation planar slip mode that is confined in a few single-slip planes and leads to in-plane softening by high pile-up stresses.

論文

Gradient residual strain measurement procedure in surface impacted railway steel axles by using neutron scattering

Zhou, L.*; Zhang, H.*; Qin, T. Y.*; Hu, F. F.*; 徐 平光; Ao, N.*; Su, Y. H.; He, L. H.*; Li, X. H.*; Zhang, J. R.*; et al.

Metallurgical and Materials Transactions A, 11 Pages, 2024/00

https://doi.org/10.1007/s11661-024-07352-5
 被引用回数：0

High-speed railway S38C axles undergo surface induction hardening for durability, but are susceptible to fatigue cracks from foreign object impact. The neutron diffraction method was employed to measure the residual strain in S38C axles, obtaining microscopic lattice distortion data, for the gradient layer at a depth of 8 mm under the surface. The results showed that after induction-hardening, the microscopic lattice distortion had a gradient distribution, decreasing with the distance from the surface. However, in the case of impacting speed of 600 km/m, the average microscopic lattice distortion increased with the distance from the surface, reaching a maximum augmentation of 55 pct. These findings indicate a strong experimental basis, and improve our understanding of the relationship between macroscopic residual stress and decision-making, in regard to operation and maintenance.

論文

Pressure-modulated magnetism and negative thermal expansion in the Ho$$_2$$Fe$$_{17}$$ intermetallic compound

Cao, Y.*; Zhou, H.*; Khmelevskyi, S.*; Lin, K.*; Avdeev, M.*; Wang, C.-W.*; Wang, B.*; Hu, F.*; 加藤 健一*; 服部 高典; et al.

Chemistry of Materials, 35(8), p.3249 - 3255, 2023/04

https://doi.org/10.1021/acs.chemmater.3c00158
 被引用回数：1 パーセンタイル：0(Chemistry, Physical)

静水圧や化学圧力は、結晶構造を変化させる効率的な刺激であり、材料科学において電気的、磁気的特性のチューニングによく利用されている。しかし、化学圧力は定量化が困難であり、これら両者の定量的な対応関係はまだよくわかっていない。本研究では、負の熱膨張(NTE)を持つ永久磁石の候補である金属間化合物を調べた。放射光X線その場観察により、AlをドープしたHo$$_2$$Fe$$_{17}$$に負の化学圧力があることを明らかにし、単位セル体積の温度・圧力依存性を用いそれを定量的に評価した。また、磁化測定と中性子回折測定を組み合わせることで、磁気秩序に対する化学圧力と静水圧の違いを比較した。興味深いことに、圧力はNTEの抑制と増強を制御するために使用することができた。電子状態計算から、圧力がFermiレベル(EF)に対する主要バンドの上部に影響を与えたことを示しており、これは磁気安定性に影響を与え、それが磁気とNTEを調節する上で重要な役割を果たしていることがわかった。本研究は、圧力の影響を理解し、それを利用して機能性材料の特性を制御する良い例を示している。

論文

Fatigue crack non-propagation behavior of a gradient steel structure from induction hardened railway axles

Zhang, H.*; Wu, S. C.*; Ao, N.*; Zhang, J. W.*; Li, H.*; Zhou, L.*; 徐 平光; Su, Y. H.

International Journal of Fatigue, 166, p.107296_1 - 107296_11, 2023/01

https://doi.org/10.1016/j.ijfatigue.2022.107296
 被引用回数：4 パーセンタイル：61.91(Engineering, Mechanical)

Abnormal damages in railway axles can lead to a significant hazard to running safety and reliability. To this end, a surface treatment was selected to effectively inhibit fatigue crack initiation and growth. In this study, a single edge notch bending fatigue test campaign with artificial notches was conducted to elucidate the fatigue crack non-propagation behavior in railway S38C axles subjected to an induction hardening process. The fatigue cracking behavior in the gradient structure was revealed by optical microscopy, electron backscatter diffraction, and fractography. The microhardness distribution was measured using a Vickers tester. The obtained results show that the microhardness of the strengthening layer is nearly triple that of the matrix. Owing to the gradient microstructures and hardness, as well as compressive residual stress, the fatigue long crack propagates faster once it passes through the hardened zone (approximately 2.0 mm in the radial depth). Thereafter, local retarding (including deflection, branching, and blunting) of the long crack occurs because of the relatively coarse ferrite and pearlite in the transition region and matrix. Totally, this fatigue cracking resistance is reasonably believed to be due to the gradient microstructure and residual stress. These findings help to tailor a suitable detection strategy for maximum defects or cracks in railway axles.

論文

Study of the $$N=32$$ and $$N=34$$ shell gap for Ti and V by the first high-precision multireflection time-of-flight mass measurements at BigRIPS-SLOWRI

飯村 俊*; Rosenbusch, M.*; 高峰 愛子*; 角田 佑介*; 和田 道治*; Chen, S.*; Hou, D. S.*; Xian, W.*; 石山 博恒*; Yan, S.*; et al.

Physical Review Letters, 130(1), p.012501_1 - 012501_6, 2023/01

https://doi.org/10.1103/PhysRevLett.130.012501
 被引用回数：5 パーセンタイル：94.66(Physics, Multidisciplinary)

The atomic masses of $$^{55}$$Sc, $$^{56,58}$$Ti, and $$^{56-59}$$V have been determined using the high-precision multireflection time-of-flight technique. The radioisotopes have been produced at RIKEN's Radioactive Isotope Beam Factory (RIBF) and delivered to the novel designed gas cell and multireflection system, which has been recently commissioned downstream of the ZeroDegree spectrometer following the BigRIPS separator. For $$^{56,58}$$Ti and $$^{56-59}$$V, the mass uncertainties have been reduced down to the order of 10 keV, shedding new light on the $$N=34$$ shell effect in Ti and V isotopes by the first high-precision mass measurements of the critical species $$^{58}$$Ti and $$^{59}$$V. With the new precision achieved, we reveal the nonexistence of the $$N=34$$ empirical two-neutron shell gaps for Ti and V, and the enhanced energy gap above the occupied $$nu$$p$$_{3/2}$$ orbit is identified as a feature unique to Ca. We perform new Monte Carlo shell model calculations including the $$nu$$d$$_{5/2}$$ and $$nu$$g$$_{9/2}$$ orbits and compare the results with conventional shell model calculations, which exclude the $$nu$$g$$_{9/2}$$ and the $$nu$$d$$_{5/2}$$ orbits. The comparison indicates that the shell gap reduction in Ti is related to a partial occupation of the higher orbitals for the outer two valence neutrons at $$N = 34$$.

論文

A Safer preprocessing system for analyzing dissolved organic radiocarbon in seawater

乙坂 重嘉*; Jeon, H.*; Hou, Y.*; 渡邊 隆広; 阿瀬 貴博*; 宮入 陽介*; 横山 祐典*; 小川 浩史*

Nuclear Instruments and Methods in Physics Research B, 527, p.1 - 6, 2022/09

https://doi.org/10.1016/j.nimb.2022.07.003
 被引用回数：0 パーセンタイル：0.02(Instruments & Instrumentation)

海水中の溶存有機物の放射性炭素(DO$$^{14}$$C)の測定により、海洋における溶存有機物の動態の時間スケールや供給源に関する情報を効果的に得ることが期待されている。しかしながら、海水中のDOC濃度は低く、近年の加速器質量分析の高性能化を考慮しても、その分析には比較的多量の海水($$sim$$1L)を要する。また、高熱を発する紫外線照射などの複雑な試料処理が必要となる。本研究では、既往の紫外線処理法よりも安全で簡便な海水中DO$$^{14}$$Cを分析する方法を開発した。特に重要な変更点は、分解システムに低圧水銀ランプを採用した点で、これによって反応時の試料温度を水試料の沸点より低温に抑えることができ、安全に処理することが可能となった。加えて本研究では、可溶性の有機物標準試料と塩化ナトリウムからなる模擬海水を用いることで、このシステムを用いたDO$$^{14}$$C分析の確度の評価方法を提案する。本法は、炭素同位体比分析だけでなく、さまざまな溶存有機態の微量元素や同位体の分析にも適用されることが期待される。

論文

A Bag model of matter condensed by the strong interaction

Miao, Z.-Q.*; Xia, C.-J.*; Lai, X.-Y.*; 丸山 敏毅; Xu, R.-X.*; Zhou, E.-P.*

International Journal of Modern Physics E, 31(4), p.2250037_1 - 2250037_20, 2022/04

https://doi.org/10.1142/S0218301322500379
 被引用回数：6 パーセンタイル：86.5(Physics, Nuclear)

It is suggested that pulsar-like compact stars are comprised entirely of strangeons (quark-clusters with three-light-flavor symmetry) and a small amount of electrons. To constrain the properties of strangeon stars, we propose a linked bag model to describe matter with the strong interaction in both 2-flavored (nucleons) and 3-flavored (hyperons, strangeons, etc.) scenarios. The parameters are calibrated to reproduce the saturation properties of nuclear matter. The energy per baryon of strangeon matter is smaller than that of baryon matter if the strangeon carries a large number of valence quarks, which stiffens the equation of state and consequently increases the maximum mass of strangeon stars. The maximum mass and tidal deformability of strangeon stars within the present model are consistent with the observation, i.e. the maximum mass of strangeon stars can be $$sim$$2.5 solar mass, and the tidal deformability of a 1.4 solar mass star can be $$180lesssimLambdalesssim340$$.

論文

Structure of an aqueous RbCl solution in the gigapascal pressure range by neutron diffraction combined with empirical potential structure refinement modeling

Zhang, W. Q.*; 山口 敏男*; Fang, C. H.*; 吉田 亨次*; Zhou, Y. Q.*; Zhu, F. Y.*; 町田 真一*; 服部 高典; Li, W.*

Journal of Molecular Liquids, 348, p.118080_1 - 118080_11, 2022/02

https://doi.org/10.1016/j.molliq.2021.118080
 被引用回数：2 パーセンタイル：34.79(Chemistry, Physical)

3mol/kgのRbCl水溶液におけるイオンの水和・会合と水素結合した水の構造を、298K/0.1MPa, 298K/1GPa, 523K/1GPa, 523K/4GPaにおける中性子回折と経験的ポテンシャル構造精密化モデリングにより調べた。その結果、構造パラメータは温度と圧力に依存していることがわかった。高圧・高温条件では、Rb$$^+$$とCl$$^-$$の第二水和層がより明確になる。第一水和層におけるRb$$^+$$の平均酸素配位数は、配位距離を0.290nmから0.288nmに縮めながら、常圧では6.3だったのが、4GPaでは8.9に増加した。第一水和シェルのCl$$^-$$の平均酸素配位数は、常圧で5.9、4GPaで9.1と圧力により増加し、対応する配位距離は0.322nmから0.314nmへと減少した。Rb$$^+$$と中心の水分子の第一溶媒和シェルにおける水双極子の配向は圧力に敏感であるが、Cl$$^-$$の第一溶媒和シェルにおける水双極子の配向は温度圧力によらずあまり変化しなかった。Rb$$^+$$-Cl$$^-$$の隣接イオンペアの数は、温度が高くなると減少し、圧力が高くなると増加する。水分子は密に詰まっており、極限状態では水分子の四面体水素結合ネットワークはもはや存在しない。

論文

Martensitic transformation in CrCoNi medium-entropy alloy at cryogenic temperature

Naeem, M.*; Zhou, H.*; He, H.*; Harjo, S.; 川崎 卓郎; Lan, S.*; Wu, Z.*; Zhu, Y.*; Wang, X.-L.*

Applied Physics Letters, 119(13), p.131901_1 - 131901_7, 2021/09

https://doi.org/10.1063/5.0067268
 被引用回数：9 パーセンタイル：62.1(Physics, Applied)

We investigated the in situ deformation behavior of the CrCoNi medium-entropy alloy at a cryogenic temperature of 140 K and compared it with deformation at room temperature. The sample exhibited higher strength and larger ductility at the cryogenic temperature. The CrCoNi alloy remained single-phase face-centered cubic at room temperature, while deformation at 140 K resulted in a martensitic transformation to the hexagonal close-packed structure. The phase transformation, an additional deformation mechanism to stacking faults, twinning, and dis- location slip, resulted in a higher work hardening at cryogenic temperature. The study addresses the structure metastability in the CrCoNi alloy, which led to the formation of epsilon-martensite from the intrinsic stacking faults.

論文

Spin Hall magnetoresistance in Pt/Cr$$_2$$O$$_3$$/YIG structure

Qi, J.*; Hou, D.*; Chen, Y.*; 齊藤 英治; Jin, X.*

Journal of Magnetism and Magnetic Materials, 534, p.167980_1 - 167980_6, 2021/09

https://doi.org/10.1016/j.jmmm.2021.167980
 被引用回数：1 パーセンタイル：7.92(Materials Science, Multidisciplinary)

Temperature dependence of the spin Hall magnetoresistance (SMR) has been investigated herein Pt/Cr$$_2$$O$$_3$$/Y$$_3$$Fe$$_5$$O$$_{12}$$ structure. Well below the N$'{e}$el temperature of Cr$$_2$$O$$_3$$, the SMR is not observed at the noise level of 1.2 ppm. In vicinity of the N$'{e}$el temperature, only a positive SMR tracks the YIG magnetic switching process, supporting that the SMR of normal metal/antiferromagnetic insulator/ferromagnetic insulator trilayer is controlled by the N$'{e}$el vector of the antiferromagnetic insulator. A high field magnetoresistance is observed up to an external magnetic field of 20000 Oe which has a field angle dependence symmetry consistent with the SMR. We attribute this high field magnetoresistance to be induced by the Hanle magnetoresistance in Pt.

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

AA2020-0819.pdf:1.29MB

https://doi.org/10.1103/PhysRevLett.126.082501
 被引用回数：43 パーセンタイル：96.7(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、$$1s_{1/2}$$と$$0d_{5/2}$$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

Enhancement of fatigue resistance by overload-induced deformation twinning in a CoCrFeMnNi high-entropy alloy

Lam, T.-N.*; Lee, S. Y.*; Tsou, N.-T.*; Chou, H.-S.*; Lai, B.-H.*; Chang, Y.-J.*; Feng, R.*; 川崎 卓郎; Harjo, S.; Liaw, P. K.*; et al.

Acta Materialia, 201, p.412 - 424, 2020/12

https://doi.org/10.1016/j.actamat.2020.10.016
 被引用回数：33 パーセンタイル：91.53(Materials Science, Multidisciplinary)

We examined fatigue-crack-growth behaviors of CoCrFeMnNi high-entropy alloys (HEAs) under as-fatigued and tensile-overloaded conditions using neutron-diffraction measurements coupled with diffraction peak-profile analyses. We applied both high-resolution transmission electron microscopy (HRTEM) and neutron-diffraction strain mapping for the complementary microstructure examinations. Immediately after a single tensile overload, the crack-growth-retardation period was obtained by enhancing the fatigue resistance, as compared to the as-fatigued condition. The combined mechanisms of the overload-induced larger plastic deformation, the enlarged compressive residual stresses and plastic-zone size, the crack-tip blunting ahead of the crack tip, and deformation twinning governed the pronounced macroscopic crack-growth-retardation behavior following the tensile overload.

論文

General synthesis of single-atom catalysts for hydrogen evolution reactions and room-temperature Na-S batteries

Lai, W.-H.*; Wang, H.*; Zheng, L.*; Jiang, Q.*; Yan, Z.-C.*; Wang, L.*; 吉川 浩史*; 松村 大樹; Sun, Q.*; Wang, Y.-X.*; et al.

Angewandte Chemie; International Edition, 59(49), p.22171 - 22178, 2020/12

https://doi.org/10.1002/anie.202009400
 被引用回数：77 パーセンタイル：95.81(Chemistry, Multidisciplinary)

Herein, we report a comprehensive strategy to synthesize a full range of single-atom metals on carbon matrix, including V, Mn, Fe, Co, Ni, Cu, Ge, Mo, Ru, Rh, Pd, Ag, In, Sn, W, Ir, Pt, Pb, and Bi. The extensive applications of various single-atom catalysts (SACs) are manifested via their ability to electro-catalyze typical hydrogen evolution reactions (HER) and conversion reactions in novel room-temperature sodium sulfur batteries (RT-Na-S). The enhanced performances for these electrochemical reactions arisen from the ability of different single active atoms on local structures to tune their electronic configuration. Significantly, the electrocatalytic behaviors of diverse SACs, assisted by density functional theory calculations, are systematically revealed by in situ synchrotron X-ray diffraction and in situ transmission electronic microscopy, providing a strategic library for the general synthesis and extensive applications of SACs in energy conversion and storage.

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

https://doi.org/10.1140/epja/s10050-020-00141-9
 被引用回数：321 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

Crystalline dependence of spin transmission in Cr$$_2$$O$$_3$$ thin films

Qin, J.*; Hou, D.*; Chen, Y.*; 齊藤 英治; Jin, X.*

Journal of Magnetism and Magnetic Materials, 501, p.166362_1 - 166362_4, 2020/05

https://doi.org/10.1016/j.jmmm.2019.166362
 被引用回数：4 パーセンタイル：26.39(Materials Science, Multidisciplinary)

Spin transmission in Cr$$_2$$O$$_3$$ films of different crystalline textures is studied experimentally. With Y$$_3$$Fe$$_5$$O$$_{12}$$/Cr$$_2$$O$$_3$$/Pt trilayer devices, a spin current is injected into Cr$$_2$$O$$_3$$ by spin pumping from Y$$_3$$Fe$$_5$$O$$_{12}$$, and the spin transmission is monitored by the inverse spin Hall voltage ($$V_mathrm{ISHE}$$) in Pt. For (0001) plane textured Cr$$_2$$O$$_3$$ films, $$V_mathrm{ISHE}$$ vanishes quickly below the N$'{e}$el temperature. However, the $$V_mathrm{ISHE}$$ shows a broad shoulder below the N$'{e}$el temperature for $$(11bar{2}0)$$ and $$(11bar{2}3)$$ plane co-textured Cr$$_2$$O$$_3$$. Such a difference in the temperature dependence of Cr$$_2$$O$$_3$$ can be understood by the different N$'{e}$el vector orientations with respect to the injected spin moment direction.

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

https://doi.org/10.1016/j.physletb.2019.135096
 被引用回数：11 パーセンタイル：79.42(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

Comparing cyclic tension-compression effects on CoCrFeMnNi high-entropy alloy and Ni-based superalloy

Lam, T.-N.*; Chou, Y.-S.*; Chang, Y.-J.*; Sui, T.-R.*; Yeh, A.-C.*; Harjo, S.; Lee, S. Y.*; Jain, J.*; Lai, B.-H.*; Huang, E.-W.*

Crystals (Internet), 9(8), p.420_1 - 420_8, 2019/08

AA2019-0503.pdf:1.06MB

https://doi.org/10.3390/cryst9080420
 被引用回数：9 パーセンタイル：67.83(Crystallography)

An equal-molar CoCrFeMnNi, face-centered-cubic (fcc) high-entropy alloy (HEA) and a nickel-based superalloy are studied using in situ neutron diffraction experiments. With continuous measurements, the evolution of diffraction peaks is collected for microscopic lattice strain analyses. Cyclic hardening and softening are found in both metallic systems. However, as obtained from the diffraction-peak-width evolution, the underneath deformation mechanisms are quite different. The CoCrFeMnNi HEA exhibits distinct lattice strain and microstructure responses under tension-compression cyclic loadings.

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

https://doi.org/10.1038/ncomms12670
 被引用回数：141 パーセンタイル：97.14(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

Precise determination of $$^{12}_{Lambda}$$C level structure by $$gamma$$-ray spectroscopy

細見 健二; Ma, Y.*; 味村 周平*; 青木 香苗*; 大樂 誠司*; Fu, Y.*; 藤岡 宏之*; 二ツ川 健太*; 井元 済*; 垣口 豊*; et al.

Progress of Theoretical and Experimental Physics (Internet), 2015(8), p.081D01_1 - 081D01_8, 2015/08

https://doi.org/10.1093/ptep/ptv113
 被引用回数：14 パーセンタイル：66.59(Physics, Multidisciplinary)

$$gamma$$線分光によって$$^{12}_{Lambda}$$Cハイパー核のレベル構造を精密に測定した。ゲルマニウム検出器群Hyperball2を用いて、$$^{12}$$C$$(pi^{+}, K^{+}gamma)$$反応からの4本の$$gamma$$線遷移を同定することに成功した。基底状態スピン二重項$$(2^{-}, 1^{-}_{1})$$のエネルギー間隔は直接遷移$$M1$$$$gamma$$線により、$$161.5pm0.3$$(stat)$$pm0.3$$(syst)keVと測定された。また、励起準位である$$1^{-}_{2}$$と$$1^{-}_{3}$$について、それぞれ、$$2832pm3pm4$$, keVと$$6050pm8pm7$$, keVと励起エネルギーを決定した。これらの測定された$$^{12}_{Lambda}$$Cの励起エネルギーは反応分光による$$lambda$$ハイパー核の実験研究において決定的な基準となる。

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

https://doi.org/10.1103/PhysRevC.89.054303
 被引用回数：5 パーセンタイル：38.03(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$$nu j$$は$$nu p_{3/2}$$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。

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