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Mictomagnetism and suppressed thermal conduction of the prototype high-entropy alloy CrMnFeCoNi

Yang, J.*; Ren, W.*; Zhao, X.*; 菊地 龍弥*; Miao, P.*; 中島 健次; Li, B.*; Zhang, Z.*

Journal of Materials Science and Technology, 99, p.55 - 60, 2022/02

物性測定と中性子散乱を組み合わせることにより、面心立方高エントロピー合金CrMnFeCoNiの磁気および熱輸送特性を調べた。DCおよびAC帯磁率は、温度領域全体で反強磁性および強磁性相互作用が共存する常磁性挙動を示し、それぞれ、常磁性から反強磁性への遷移、反強磁性から強磁性への遷移、およびスピン凍結に対応して、約80, 50、および20Kで3つの異常が見られる。電気伝導率と熱伝導率はNiに比べて大幅に低下しており、格子熱伝導率の温度依存性はガラスのようなプラトーを示す。非弾性中性子散乱測定は弱い非調和性を示唆し、熱輸送は欠陥散乱によって支配されると思われる。


Stacking fault driven phase transformation in CrCoNi medium entropy alloy

He, H.*; Naeem, M.*; Zhang, F.*; Zhao, Y.*; Harjo, S.; 川崎 卓郎; Wang, B.*; Wu, X.*; Lan, S.*; Wu, Z.*; et al.

Nano Letters, 21(3), p.1419 - 1426, 2021/02

 被引用回数:3 パーセンタイル:0(Chemistry, Multidisciplinary)

In CrCoNi, a so-called medium-entropy alloy, an fcc-to-hcp phase transformation has long been anticipated. Here, we report an in situ loading study with neutron diffraction, which revealed a bulk fcc-to-hcp phase transformation in CrCoNi at 15 K under tensile loading. By correlating deformation characteristics of the fcc phase with the development of the hcp phase, it is shown that the nucleation of the hcp phase was triggered by intrinsic stacking faults. The confirmation of a bulk phase transformation adds to the myriads of deformation mechanisms available in CrCoNi, which together underpin the unusually large ductility at low temperatures.


Magnetic-field and composition tuned antiferromagnetic instability in the quantum spin-liquid candidate NaYbO$$_2$$

Guo, J.*; Zhao, X.*; 河村 聖子; Ling, L.*; Wang, J.*; He, L.*; 中島 健次; Li, B.*; Zhang, Z.*

Physical Review Materials (Internet), 4(6), p.064410_1 - 064410_7, 2020/06

 被引用回数:4 パーセンタイル:51.8(Materials Science, Multidisciplinary)

NaYbO$$_2$$ has been reported as a possible host for the quantum spin-liquid state. Here, the composition-dependent polycrystalline Na$$_{1-x}$$YbO$$_2$$ ($$x = 0$$, 0.03, and 0.07) has been investigated by combining high-field magnetizations and inelastic neutron scattering techniques. For the $$x = 0$$ sample, no signature of a magnetic order is observed down to 0.3 K. Inelastic neutron scattering measurement suggests a continuous low-energy excitation spectrum centered at momentum transfer $$(Q) sim 1.25$$~$AA$^{-1}$$ and extending up to energy transfer $$(E) sim 2.0$$~meV. In contrast, $$x = 0.03$$ and 0.07 samples exhibit magnetic transitions at 1.1 and 2.3 K, respectively. High-field magnetization measurements indicate similar behaviors for $$x = 0$$ and 0.03 samples including plateau-like features at the 1/3 saturated magnetization, which implies that the spin disorder in the $$x = 0$$ sample might be suppressed preceding the emergence of the up-up-down phase. This composition- and field-dependent study allows us to construct complete phase diagrams indicating that NaYbO$$_2$$ is a promising candidate for the quantum spin-liquid state in close proximity to the antiferromagnetic instability tuned by the application of magnetic fields as well as controlling the concentration of Na$$^+$$ ion vacancies.


Ultralow thermal conductivity from transverse acoustic phonon suppression in distorted crystalline $$alpha$$-MgAgSb

Li, X.*; Liu, P.-F.*; Zhao, E.*; Zhang, Z.*; Guide, T.*; Le, M. D.*; Avdeev, M.*; 池田 一貴*; 大友 季哉*; 古府 麻衣子; et al.

Nature Communications (Internet), 11(1), p.942_1 - 942_9, 2020/02

 被引用回数:15 パーセンタイル:93.25(Multidisciplinary Sciences)



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.


Comparison of heavy-ion transport simulations; Collision integral with pions and $$Delta$$ resonances in a box

小野 章*; Xu, J.*; Colonna, M.*; Danielewicz, P.*; Ko, C. M.*; Tsang, M. B.*; Wang, Y,-J.*; Wolter, H.*; Zhang, Y.-X.*; Chen, L.-W.*; et al.

Physical Review C, 100(4), p.044617_1 - 044617_35, 2019/10


 被引用回数:29 パーセンタイル:98.33(Physics, Nuclear)



Evidence for singular-phonon-induced nematic superconductivity in a topological superconductor candidate Sr$$_{0.1}$$Bi$$_{2}$$Se$$_{3}$$

Wang, J.*; Ran, K.*; Li, S.*; Ma, Z.*; Bao, S.*; Cai, Z.*; Zhang, Y.*; 中島 健次; 河村 聖子; $v{C}$erm$'a$k, P.*; et al.

Nature Communications (Internet), 10, p.2802_1 - 2802_6, 2019/06

 被引用回数:12 パーセンタイル:83.95(Multidisciplinary Sciences)

Superconductivity mediated by phonons is typically conventional, exhibiting a momentum-independent $$s$$-wave pairing function, due to the isotropic interactions between electrons and phonons along different crystalline directions. Here, by performing inelastic neutron scattering measurements on a superconducting single crystal of Sr$$_{0.1}$$Bi$$_{2}$$Se$$_{3}$$, a prime candidate for realizing topological superconductivity by doping the topo-logical insulator Bi$$_{2}$$Se$$_{3}$$, we found that there exist singular phonons, with the linewidths of the acoustic phonons increasing substantially at long wavelengths, but only for those along the [001] direction. This observation indicates a large and singular electron-phonon coupling at small momenta, which we propose to give rise to the exotic $$p$$-wave nematic superconducting pairing in the MxBi$$_{2}$$Se$$_{3}$$ (M = Cu, Sr, Nb) superconductor family. Therefore, we show that these superconductors may be the first examples where electron-phonon interaction can induce more exotic superconducting pairing than the $$s$$-wave.


Passive sweat collection and colorimetric analysis of biomarkers relevant to kidney disorders using a soft microfluidic system

Zhang, Y.*; Guo, H.*; Kim, S. B.*; Wu, Y.*; Ostojich, D.*; Park, S. H.*; Wang, X.*; Weng, Z.*; Li, R.*; Bandodkar, A. J.*; et al.

Lab on a Chip, 19(9), p.1545 - 1555, 2019/05

 被引用回数:54 パーセンタイル:99.34(Biochemical Research Methods)



Coexistence of ferromagnetic and stripe-type antiferromagnetic spin fluctuations in YFe$$_{2}$$Ge$$_{2}$$

Wo, H.*; Wang, Q.*; Shen, Y.*; Zhang, X.*; Hao, Y.*; Feng, Y.*; Shen, S.*; He, Z.*; Pan, B.*; Wang, W.*; et al.

Physical Review Letters, 122(21), p.217003_1 - 217003_5, 2019/05

 被引用回数:2 パーセンタイル:35.62(Physics, Multidisciplinary)

We report neutron scattering measurements of single-crystalline YFe$$_{2}$$Ge$$_{2}$$ in the normal state, which has the same crystal structure as the 122 family of iron pnictide superconductors. YFe$$_{2}$$Ge$$_{2}$$ does not exhibit long-range magnetic order but exhibits strong spin fluctuations. Like the iron pnictides, YFe$$_{2}$$Ge$$_{2}$$ displays anisotropic stripe-type antiferromagnetic spin fluctuations at ($$pi, 0, pi$$). More interesting, however, is the observation of strong spin fluctuations at the in-plane ferromagnetic wave vector ($$0, 0, pi$$). These ferromagnetic spin fluctuations are isotropic in the ($$H, K$$) plane, whose intensity exceeds that of stripe spin fluctuations. Both the ferromagnetic and stripe spin fluctuations remain gapless down to the lowest measured energies. Our results naturally explain the absence of magnetic order in YFe$$_{2}$$Ge$$_{2}$$ and also imply that the ferromagnetic correlations may be a key ingredient for iron-based materials.


Proton shell evolution below $$^{132}$$Sn; First measurement of low-lying $$beta$$-emitting isomers in $$^{123,125}$$Ag

Chen, Z. Q.*; Li, Z. H.*; Hua, H.*; 渡邉 寛*; Yuan, C. X.*; Zhang, S. Q.*; Lorusso, G.*; Orlandi, R.; 他60名*

Physical Review Letters, 122(21), p.212502_1 - 212502_6, 2019/05

 被引用回数:11 パーセンタイル:82.27(Physics, Multidisciplinary)

$$beta$$-delayed $$gamma$$-ray spectroscopy of the neutron-rich isotopes $$^{123,125}$$Ag was carried out at RIBF, RIKEN. The long predicted 1/2$$^{-}$$ $$beta$$ emitting isomers were identified in both nuclei for the first time. The new experimental results extend the systematic trend of energy spacing between the lowest 9/2$$^+$$ and 1/2$$^{-}$$ levels in Ag isotopes up to N=78, providing a clear signal for the reduction of the Z=40 subshell gap in Ag towards N=82. The tensor force is found to play a key role in the reduction of the Z=40 sub-shell gap.


Comparison of heavy-ion transport simulations; Collision integral in a box

Zhang, Y.-X.*; Wang, Y,-J.*; Colonna, M.*; Danielewicz, P.*; 小野 章*; Tsang, M. B.*; Wolter, H.*; Xu, J.*; Chen, L.-W.*; Cozma, D.*; et al.

Physical Review C, 97(3), p.034625_1 - 034625_20, 2018/03

 被引用回数:63 パーセンタイル:99.37(Physics, Nuclear)

2017年4月に開催された国際会議Transport2017において、重イオン核反応モデルの国際的な比較が議論された。重イオン加速器の安全評価や宇宙飛行士の被ばく評価等で重要な役割を果たすため、世界中で重イオン核反応の様々な理論モデルが開発されている。本研究はモデル間の共通点と差異を明らかにし、各モデルの問題点を明らかにした。比較において、辺の長さが20fmの直方体に320個の中性子と320個の陽子をランダム配置し、それらが時間発展に伴って起こす散乱の回数や散乱時のエネルギーなどを計算する条件が設定された。また、結果以外にも、理論モデルを構成するアルゴリズムについても比較を行った。発表者は重イオン核反応モデルJQMD(JAERI Quantum Molecular Dynamics)を用いて計算を行い、世界で開発されている15の計算コードによる計算結果と比較した。コードアルゴリズムの比較では、JQMDは必ず陽子から 優先的に衝突確率を計算し、その後に中性子の衝突を計算するため、物理描像の妥当性が指摘された。一方、JQMDは他のモデルとほぼ同じ計算結果を出すことも判明した。衝突回数や運動量の計算値が平均から2倍以上乖離するモデルもある中で、JQMDは本計算条件で安定した性能を発揮することが確認された。


Effect of storage environment on hydrogen generation by the reaction of Al with water

Wang, Y.-Q.*; Gai, W.-Z.*; Zhang, X.-Y.*; Pan, H.-Y.*; Cheng, Z.-X.*; 徐 平光; Deng, Z.-Y.*

RSC Advances (Internet), 7(4), p.2103 - 2109, 2017/01


 被引用回数:18 パーセンタイル:66.56(Chemistry, Multidisciplinary)

Al powder was stored in saturated water vapor, oxygen, nitrogen and drying air separately for a time period up to about six months, the degradation behavior of Al activity was characterized by the reaction of Al with water. It was found that water vapor decreased the induction time for the beginning of Al-water reaction and reduced the total hydrogen generation per unit weight of Al, while oxygen increased the induction time and retarded the Al-water reaction. In contrast, the effect of nitrogen and drying air on Al activity was weak. The mechanism analyses indicated that water vapor promoted the hydration of Al surface passive oxide film and speeded up the reaction of Al with water, while oxygen thickened the passive oxide film of Al surface and prolonged its hydration process. These imply that water vapor rather than oxygen is responsible for the degradation of Al activity during storage under ambient condition.


Colossal negative thermal expansion induced by magnetic phase competition on frustrated lattices in Laves phase compound (Hf,Ta)Fe$$_2$$

Li, B.; Luo, X. H.*; Wang, H.*; Ren, W. J.*; Yano, S.*; Wang, C.-W.*; Gardner, J. S.*; Liss, K.-D.*; Miao, P.*; Lee, S.-H.*; et al.

Physical Review B, 93(22), p.224405_1 - 224405_6, 2016/06

 被引用回数:33 パーセンタイル:83.88(Materials Science, Multidisciplinary)

Competition between ferromagnetic and antiferromagnetic phases on frustrated lattices in hexagonal Laves phase compound Hf$$_{0.86}$$Ta$$_{0.14}$$Fe$$_2$$ is investigated by using neutron diffraction as a function of temperature and magnetic fields and density-functional-theory calculations. At 325 K, the compound orders into the 120$$^{circ}$$ frustrated antiferromagnetic state with well-reduced magnetic moment and an in-plane lattice contraction simultaneously sets in. With further cooling down, however, the accumulated distortion in turn destabilizes this susceptible frustrated structure. The frustration is completely relieved at 255 K when the first-order transition to the ferromagnetic state takes place, where a colossal negative volumetric thermal expansion, $$-123 times 10^{-6}$$/K, is obtained. Meanwhile, the antiferromagnetic state can be suppressed by few Tesla magnetic fields, which results in a colossal positive magnetostriction. Such delicate competition is attributed to the giant magnetic fluctuation inherent in the frustrated antiferromagnetic state. Therefore, the magnetoelastic instability is approached even under a small perturbation.


Enhanced damage buildup in C$$^{+}$$-implanted GaN film studied by a monoenergetic positron beam

Li, X. F.*; Chen, Z. Q.*; Liu, C.*; Zhang, H.; 河裾 厚男

Journal of Applied Physics, 117(8), p.085706_1 - 085706_6, 2015/02

 被引用回数:21 パーセンタイル:72.73(Physics, Applied)



Diluted ferromagnetic semiconductor Li(Zn,Mn)P with decoupled charge and spin doping

Deng, Z.*; Zhao, K.*; Gu, B.; Han, W.*; Zhu, J. L.*; Wang, X. C.*; Li, X.*; Liu, Q. Q.*; Yu, R. C.*; 後神 達郎*; et al.

Physical Review B, 88(8), p.081203_1 - 081203_5, 2013/08

 被引用回数:66 パーセンタイル:92.87(Materials Science, Multidisciplinary)

We report the discovery of a diluted magnetic semiconductor, Li(Zn,Mn)P, in which charge and spin are introduced independently via lithium off-stoichiometry and the isovalent substitution of Mn$$^{2+}$$ for Zn$$^{2+}$$, respectively. Isostructural to (Ga,Mn)As, Li(Zn,Mn)P was found to be a ${it p}$-type ferromagnetic semiconductor with excess lithium providing charge doping. First-principles calculations indicate that excess Li is favored to partially occupy the Zn site, leading to hole doping. Ferromagnetism with Curie temperature up to 34 K is achieved while the system still shows semiconducting transport behavior.


Anisotropic two-dimensional electron gas at the LaAlO$$_{3}$$/SrTiO$$_{3}$$ (110) interface

Annadi, A.*; Zhang, Q.*; Renshaw Wang, X.*; Tuzla, N.*; Gopinadhan, K.*; L$"u$, W. M.*; Roy Barman, A.*; Liu, Z. Q.*; Srivastava, A.*; Saha, S.*; et al.

Nature Communications (Internet), 4, p.1838_1 - 1838_7, 2013/05

 被引用回数:84 パーセンタイル:94.96(Multidisciplinary Sciences)

We report the observation of unexpected conductivity at the LaAlO$$_{3}$$/SrTiO$$_{3}$$ interface prepared on (110)-oriented SrTiO$$_{3}$$, with a LaAlO$$_{3}$$-layer thickness-dependent metal-insulator transition. Density functional theory calculation reveals that electronic reconstruction, and thus conductivity, is still possible at this (110) interface by considering the energetically favourable (110) interface structure, that is, buckled TiO$$_{2}$$/LaO, in which the polarization discontinuity is still present. The conductivity was further found to be strongly anisotropic along the different crystallographic directions with potential for anisotropic superconductivity and magnetism, leading to possible new physics and applications.


Li(Zn,Mn)As as a new generation ferromagnet based on a I-II-V semiconductor

Deng, Z.*; Jin, C. Q.*; Liu, Q. Q.*; Wang, X. C.*; Zhu, J. L.*; Feng, S. M.*; Chen, L. C.*; Yu, R. C.*; Arguello, C.*; 後神 達郎*; et al.

Nature Communications (Internet), 2, p.1425_1 - 1425_5, 2011/08

 被引用回数:137 パーセンタイル:93.89(Multidisciplinary Sciences)



Event structure and double helicity asymmetry in jet production from polarized $$p + p$$ collisions at $$sqrt{s}$$ = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Y.*; Al-Bataineh, H.*; Alexander, J.*; Aoki, K.*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review D, 84(1), p.012006_1 - 012006_18, 2011/07

 被引用回数:25 パーセンタイル:72.31(Astronomy & Astrophysics)

重心エネルギー200GeVでの縦偏極陽子陽子衝突からのジェット生成のイベント構造と二重非対称($$A_{LL}$$)について報告する。光子と荷電粒子がPHENIX実験で測定され、イベント構造がPHYTIAイベント生成コードの結果と比較された。再構成されたジェットの生成率は2次までの摂動QCDの計算で十分再現される。測定された$$A_{LL}$$は、一番低い横運動量で-0.0014$$pm$$0.0037、一番高い横運動量で-0.0181$$pm$$0.0282であった。この$$A_{LL}$$の結果を幾つかの$$Delta G(x)$$の分布を仮定した理論予想と比較する。


Identified charged hadron production in $$p + p$$ collisions at $$sqrt{s}$$ = 200 and 62.4 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; 秋葉 康之*; Al-Bataineh, H.*; Alexander, J.*; 青木 和也*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review C, 83(6), p.064903_1 - 064903_29, 2011/06

 被引用回数:156 パーセンタイル:99.42(Physics, Nuclear)

200GeVと62.4GeVでの陽子陽子の中心衝突からの$$pi, K, p$$の横運動量分布及び収量をRHICのPHENIX実験によって測定した。それぞれエネルギーでの逆スロープパラメーター、平均横運動量及び単位rapidityあたりの収量を求め、異なるエネルギーでの他の測定結果と比較する。また$$m_T$$$$x_T$$スケーリングのようなスケーリングについて示して陽子陽子衝突における粒子生成メカニズムについて議論する。さらに測定したスペクトルを二次の摂動QCDの計算と比較する。


Azimuthal correlations of electrons from heavy-flavor decay with hadrons in $$p+p$$ and Au+Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; 秋葉 康之*; Al-Bataineh, H.*; Alexander, J.*; 青木 和也*; Aphecetche, L.*; Aramaki, Y.*; et al.

Physical Review C, 83(4), p.044912_1 - 044912_16, 2011/04

 被引用回数:8 パーセンタイル:52.71(Physics, Nuclear)


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