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論文

Synthesis of BaSiH hydridosilicate at high pressures; A Bridge to BaSiH polyhydride

Beyer, D. C.*; Spektor, K.*; Vekilova, O. Y.*; Grins, J.*; Barros Brant Carvalho, P. H.*; Leinbach, L. J.*; Sannemo-Targama, M.*; Bhat, S.*; Baran, V.*; Etter, M.*; et al.

ACS Omega (Internet), 10(15), p.15029 - 15035, 2025/04

https://doi.org/10.1021/acsomega.4c10502

被引用回数：0 パーセンタイル：0.00(Chemistry, Multidisciplinary)

SiH八面体部位を特徴とするヒドリドケイ酸塩は、水素貯蔵と水素化物イオン伝導に関連する潜在的な性質を持つかなり新しい化合物のクラスである。ここでは、Zintl相水素化物BaSiH $_{sim 1.8}$ を4GPa以上の圧力でH流体と反応させ、その後常圧まで減圧して得られた新しい代表的なBaSiHについて報告する。SiH $_{6}^{2-}$ イオンはBa $^{2+}$ 対イオンによって八面体に配位している。Ba原子とSi原子の配置は理想的なfcc NaCl構造からわずかにずれている。IRとラマンスペクトルからSiH $_{6}^{2-}$ の屈曲と伸縮モードがそれぞれ800-1200と1400-1800cm $^{-1}$ の範囲で観測された。BaSiHは95Cまで熱的に安定であり、それ以上ではBaHとSiに分解する。DFT計算により、直接バンドギャップは2.5eVであることが示された。BaSiHの発見により、ギガパスカル圧力(10GPa以下)のシリサイドの水素化反応からアクセス可能なヒドリドケイ酸塩の化合物クラスが固まった。BaSiHの構造的性質は、超伝導ポリハイドライドBaSiHを予測されるより高い圧力で水素化するための中間体(あるいは前駆体)であることを示唆している。

論文

Unusual low-temperature ductility increase mediated by dislocations alone

Naeem, M.*; Ma, Y.*; Tian, J.*; Kong, H.*; Romero-Resendiz, L.*; Fan, Z.*; Jiang, F.*; Gong, W.; Harjo, S.; Wu, Z.*; et al.

Materials Science & Engineering A, 924, p.147819_1 - 147819_10, 2025/02

https://doi.org/10.1016/j.msea.2025.147819

被引用回数：1 パーセンタイル：0.00(Nanoscience & Nanotechnology)

Face-centered cubic (fcc) medium-/high-entropy alloys (M/HEAs) typically enhance strength and ductility at cryogenic temperatures via stacking faults, twinning, or martensitic transformation. However, in-situ neutron diffraction on VCoNi MEA at 15 K reveals that strain hardening is driven solely by rapid dislocation accumulation, without these mechanisms. This results in increased yield strength, strain hardening, and fracture strain. The behavior, explained by the Orowan equation, challenges conventional views on cryogenic strengthening in fcc M/HEAs and highlights the role of dislocation-mediated plasticity at low temperatures.

論文

Strong low-energy rattling modes enabled liquid-like ultralow thermal conductivity in a well-ordered solid

Liu, P.-F.*; Li, X.*; Li, J.*; Zhu, J.*; Tong, Z.*; 古府麻衣子*; 楡井真実; Xu, J.*; Yin, W.*; Wang, F.*; et al.

National Science Review, 11(12), p.nwae216_1 - nwae216_10, 2024/12

https://doi.org/10.1093/nsr/nwae216

被引用回数：13 パーセンタイル：94.32(Multidisciplinary Sciences)

Crystalline solids exhibiting inherently low lattice thermal conductivity ( $kappa_{rm L}$ ) are of great importance in applications such as thermoelectrics and thermal barrier coatings. However, $kappa_{rm L}$ cannot be arbitrarily low and is limited by the minimum thermal conductivity related to phonon dispersions. In this work, we report the liquid-like thermal transport in a well-ordered crystalline CsAgTe, which exhibits an extremely low $kappa_{rm L}$ value of 0.18 Wm $^{-1}$ K $^{-1}$ . On the basis of first-principles calculations and inelastic neutron scattering measurements, we find that there are lots of low-lying optical phonon modes at 3.1 meV hosting the avoided-crossing behavior with acoustic phonons. These strongly localized modes are accompanied by weakly bound rattling Ag atoms with thermally induced large amplitudes of vibrations. Using the two-channel model, we demonstrate that coupling of the particle-like phonon modes and the heat-carrying wave-like phonons is essential for understanding the low $kappa_{rm L}$ , which is heavily deviated from the temperature dependence of the standard Peierls theory. In addition, our analysis indicates that the soft structural framework with liquid-like motions of the fluctuating Ag atoms is the underlying cause that leads to the suppression of the heat conduction in CsAgTe. These factors synergistically account for the ultralow $kappa_{rm L}$ value. Our results demonstrate that the liquid-like heat transfer could indeed exist in a well-ordered crystal.

論文

Enhanced cryogenic mechanical properties of heterostructured CrCoNi multicomponent alloy; Insights from neutron diffraction

Naeem, M.*; Ma, Y.*; Knowles, A. J.*; Gong, W.; Harjo, S.; Wang, X.-L.*; Romero Resendiz, L.*; 他6名*

Materials Science & Engineering A, 916, p.147374_1 - 147374_8, 2024/11

https://doi.org/10.1016/j.msea.2024.147374

被引用回数：3 パーセンタイル：57.76(Nanoscience & Nanotechnology)

Heterostructured materials (HSMs) improve the strength-ductility trade-off of alloys, but their cryogenic performance under real-time deformation is unclear. We studied heterostructured CrCoNi medium-entropy alloy via neutron diffraction at 77 K and 293 K. A significant mechanical mismatch between fine and coarse grains led to an exceptional yield strength of 918 MPa at 293 K, increasing to 1244 MPa at 77 K with a uniform elongation of 34%. This strength-ductility synergy at 77 K is attributed to high dislocation pile-up density, increased planar faults, and martensitic transformation. Compared to homogeneous alloys, HSMs show promise for enhancing cryogenic mechanical performance in medium-/high-entropy alloys.

論文

Progress of material characterization techniques based on neutron Bragg-edge transmission imaging

Wang, Y. W.*; 徐平光; Su, Y. H.; Ma, Y. L.*; Wang, H. H.*

Physics Examination and Testing, 42(4), p.32 - 41, 2024/08

https://doi.org/10.13228/j.boyuan.issn1001-0777.20230085

With the rapid technological development of large spallation neutron source facilities, the neutron beam flux obtained has been greatly improved and neutron imaging techniques have been further developed. Due to the limitation of neutron beam flux, conventional neutron imaging techniques require neutron beams with a wide wavelength range to obtain relatively high neutron beam flux conditions. Recently, spallation neutron sources using large proton accelerators have made it possible to obtain high-flux pulsed neutron beams. Energy (wavelength) resolved neutron imaging technique based on the Bragg edge effect (neutron Bragg edge transmission imaging technique) is expected to have a wide range of applications because of its high energy resolution, high spatial resolution, and ability to detect crystallographic information. The basic principle of this technique is briefly introduced. Several applications in the evaluation of residual strain, phase composition, dislocation density, and oriented structure are also reviewed to play an active role in promoting the wider applications of related technique.

論文

Microscopic insights of the extraordinary work-hardening due to phase transformation

Ma, Y.*; Naeem, M.*; Zhu, L.*; He, H.*; Sun, X.*; Yang, Z.*; He, F.*; Harjo, S.; 川崎卓郎; Wang, X.-L.*

Acta Materialia, 270, p.119822_1 - 119822_13, 2024/05

https://doi.org/10.1016/j.actamat.2024.119822

被引用回数：10 パーセンタイル：94.16(Materials Science, Multidisciplinary)

We report an in situ neutron diffraction study of 316 L that reveals an extraordinary work-hardening rate (WHR) of 7 GPa at 15 K. Detailed analyses show that the major contribution to the excellent strength and ductility comes from the transformation-induced plasticity (TRIP) effect, introduced by the austenite-to-martensite (-to-') phase transition. A dramatic increase in the WHR is observed along with the transformation; the WHR declined when the austenite phase is exhausted. During plastic deformation, the volume-fraction weighted phase stress and stress contribution from the '-martensite increase significantly. The neutron diffraction data further suggest that the -to-' phase transformation was mediated by the -martensite, as evidenced by the concurrent decline of the phase with the phase.

論文

A One-third magnetization plateau phase as evidence for the Kitaev interaction in a honeycomb-lattice antiferromagnet

Shangguan, Y.*; Bao, S.*; Dong, Z.-Y.*; Xi, N.*; Gao, Y.-P.*; Ma, Z.*; Wang, W.*; Qi, Z.*; Zhang, S.*; Huang, Z.*; et al.

Nature Physics, 19(12), p.1883 - 1889, 2023/09

https://doi.org/10.1038/s41567-023-02212-2

被引用回数：19 パーセンタイル：93.50(Physics, Multidisciplinary)

The magnetization of a quantum magnet can be pinned at a fraction of its saturated value by collective effects. One example of such a plateau phase is found in spin-1/2 triangular-lattice antiferromagnets. They feature strong geometrical frustration and the plateau phase therein is often interpreted as arising from an order-by-disorder mechanism driven by quantum fluctuations. Here we observe a one-third magnetization plateau under an applied magnetic field in the spin-1 antiferromagnet Na $_{3}$ Ni $_{2}$ BiO $_{6}$ with a honeycomb lattice, which, with conventional magnetic interactions, would not be geometrically frustrated. Based on our elastic neutron scattering measurements, we propose the spin structure of the plateau phase to be an unusual partial spin-flop ferrimagnetic order. Our theoretical calculations indicate that bond-anisotropic Kitaev interactions are the source of frustration that produces the plateau. These results suggest that Kitaev interactions provide a different route to frustration and phases driven by quantum fluctuations in high-spin magnets.

論文

First observation of $^{28}$ O

近藤洋介*; Achouri, N. L.*; Al Falou, H.*; Atar, L.*; Aumann, T.*; 馬場秀忠*; Boretzky, K.*; Caesar, C.*; Calvet, D.*; Chae, H.*; et al.

Nature, 620(7976), p.965 - 970, 2023/08

https://doi.org/10.1038/s41586-023-06352-6

被引用回数：29 パーセンタイル：95.28(Multidisciplinary Sciences)

非常に中性子が過剰な原子核 $^{28}$ Oは、陽子、中性子ともに魔法数であることから古くからその性質に興味が持たれていたが、酸素の最後の束縛核 $^{24}$ Oよりも中性子が4個も多いため、これまで観測されてこなかった。この論文では、理化学研究所RIBFにて $^{29}$ Fからの1陽子ノックアウト反応によって $^{28}$ Oを生成し、そこから放出される中性子を測定することによって初めてその観測に成功した。核構造の観点からは、 $^{28}$ Oでは二重閉殻が保たれているか興味が持たれていたが、実験で得られた分光学的因子が殻模型計算で予言されて程度の大きいことから、閉殻構造をもたない可能性が高いことがわかった。

論文

Intruder configurations in $^{29}$ Ne at the transition into the island of inversion; Detailed structure study of $^{28}$ Ne

Wang, H.*; 安田昌弘*; 近藤洋介*; 中村隆司*; Tostevin, J. A.*; 緒方一介*; 大塚孝治*; Poves, A.*; 清水則孝*; 吉田数貴; et al.

Physics Letters B, 843, p.138038_1 - 138038_9, 2023/08

https://doi.org/10.1016/j.physletb.2023.138038

被引用回数：4 パーセンタイル：67.28(Astronomy & Astrophysics)

$^{29}$ Neからの1中性子除去反応を用いて、 $^{28}$ Neの詳細な線分光を行った。平行運動量分布の解析に基づき、 $^{28}$ Neの準位構造とスピンパリティを決定し、初めて負のパリティ状態を同定した。測定された断面積と運動量分布から、N=20とN=28のシェルギャップの消失の証拠となる有意なintruder p-wave強度が明らかになった。束縛状態については、弱いf-waveの可能性のある強度が観測された。いくつかの有効相互作用を用いた大規模殻模型計算では、実験的に観測された大きなp-wave強度と小さなf-wave強度は再現されず、Ne同位体に沿った反転の島への遷移の完全な理論的記述への挑戦が続いていることを示している。

論文

Fine structure in the decay of the 8 $^{+}$ isomer in $^{216,218}$ U

Zhang, M. M.*; Tian, Y. L.*; Wang, Y. S.*; Zhang, Z. Y.*; Gan, Z. G.*; Yang, H. B.*; Huang, M. H.*; Ma, L.*; Yang, C. L.*; Wang, J. G.*; et al.

Physical Review C, 106(2), p.024305_1 - 024305_6, 2022/08

https://doi.org/10.1103/PhysRevC.106.024305

被引用回数：5 パーセンタイル：60.14(Physics, Nuclear)

The extremely neutron-deficient even-even uranium isotopes $^{216,218}$ U were produced in the complete-fusion reactions induced by impinging $^{40}$ Ar and $^{40}$ Ca ions on $^{180,182,184}$ W targets. Fusion evaporation residues were separated in flight by the gas-filled recoil separator SHANS (Spectrometer for Heavy Atoms and Nuclear Structure) and subsequently identified using the recoil--correlation method. In this paper, we report on new -decay activities with $E_{alpha} = 10163(27)$ keV for $^{216}$ U and $E_{alpha} = 10073(16)$ keV for $^{218}$ U, which decay from the 8 $^{+}$ isomeric states of $^{216,218}$ U into the 2 $^{+}$ states of their daughter nuclei $^{212,214}$ Th, respectively. The new results extend the systematics of the -decay fine structure for the = 124 and 126 even-even isotones.

論文

Metalloid substitution elevates simultaneously the strength and ductility of face-centered-cubic high-entropy alloys

Wei, D.*; Wang, L.*; Zhang, Y.*; Gong, W.; 都留智仁; Lobzenko, I.; Jiang, J.*; Harjo, S.; 川崎卓郎; Bae, J. W.*; et al.

Acta Materialia, 225, p.117571_1 - 117571_16, 2022/02

https://doi.org/10.1016/j.actamat.2021.117571

被引用回数：97 パーセンタイル：99.64(Materials Science, Multidisciplinary)

Recently-developed high-entropy alloys (HEAs) containing multiple principal metallic elements have ex-tended the compositional space of solid solutions and the range of their mechanical properties. Here we show that the realm of possibilities can be further expanded through substituting the constituent metals with metalloids, which are desirable for tailoring strength/ductility because they have chemical interactions and atomic sizes distinctly different from the host metallic elements. Specifically, the metalloid substitution increases local lattice distortion and short-range chemical inhomogeneities to elevate strength, and in the meantime reduces the stacking fault energy to discourage dynamic recovery and encourage defect accumulation via partial-dislocation-mediated activities. These impart potent dislocation storage to improve the strain hardening capability, which is essential for sustaining large tensile elongation. As such, metalloid substitution into HEAs evades the normally expected strength-ductility trade-off, enabling an unusual synergy of high tensile strength and extraordinary ductility for these single-phase solid solutions.

論文

Neutron spectroscopy evidence on the dual nature of magnetic excitations in a van der Waals metallic ferromagnet Fe $_{2.75}$ GeTe $_{2}$

Bao, S.*; Wang, W.*; Shangguan, Y.*; Cai, Z.*; Dong, Z.-Y.*; Huang, Z.*; Si, W.*; Ma, Z.*; 梶本亮一; 池内和彦*; et al.

Physical Review X, 12(1), p.011022_1 - 011022_15, 2022/02

https://doi.org/10.1103/PhysRevX.12.011022

被引用回数：35 パーセンタイル：95.19(Physics, Multidisciplinary)

In the local or itinerant extreme, magnetic excitations can be described by the Heisenberg model which treats electron spins as localized moments, or by the itinerant-electron model where the exchange interaction between electrons leads to unequal numbers of electrons with up and down spins. However, the nature of the magnetic excitations has been elusive when both local moments and itinerant electrons are present in the intermediate range. Using inelastic neutron scattering, we provide direct spectroscopic evidence on the coexistence of and interplay between local moments and itinerant electrons in a van der Waals metallic ferromagnet Fe $_{2.72}$ GeTe $_{2}$ , which can sustain tunable room-temperature ferromagnetism down to the monolayer limit. We find that there exist ferromagnetic spin-wave excitations dispersing from the zone center at low energies resulting from local moments and a columnlike broad continuum at the zone boundary at high energies up to over 100 meV resulting from itinerant electrons. Unlike the two-dimensional crystal structure, the low-energy mode exhibits a three-dimensional nature, and the high-energy mode also has an out-of-plane dependence. Both modes persist well above the Curie temperature of 160 K. Our neutron spectroscopic data reveal that the low-energy spin waves at 100 K are more coherent than those at 4 K, which is evidence of the weakening of the Kondo screening at high temperatures. These results unambiguously demonstrate the coexistence of local moments and itinerant electrons and the Kondo effect between these two components in Fe $_{2.72}$ GeTe $_{2}$ . Such behaviors are generally expected in heavy-fermion systems with heavy electrons but are rarely clearly observed in materials with light electrons. These findings shed light on the understanding of magnetism in transition-metal compounds.

論文

Evidence for strong correlations at finite temperatures in the dimerized magnet Na $_{2}$ Cu $_{2}$ TeO $_{6}$

Shangguan, Y.*; Bao, S.*; Dong, Z.-Y.*; Cai, Z.*; Wang, W.*; Huang, Z.*; Ma, Z.*; Liao, J.*; Zhao, X.*; 梶本亮一; et al.

Physical Review B, 104(22), p.224430_1 - 224430_8, 2021/12

https://doi.org/10.1103/PhysRevB.104.224430

被引用回数：2 パーセンタイル：10.46(Materials Science, Multidisciplinary)

Dimerized magnets forming alternating Heisenberg chains exhibit quantum coherence and entanglement and thus can find potential applications in quantum information and computation. However, magnetic systems typically undergo thermal decoherence at finite temperatures. Here, we show inelastic neutron scattering results on an alternating antiferromagnetic-ferromagnetic chain compound Na $_{2}$ Cu $_{2}$ TeO $_{6}$ that the excited quasiparticles can counter thermal decoherence and maintain strong correlations at elevated temperatures. At low temperatures, we observe clear dispersive singlet-triplet excitations arising from the dimers formed along the crystalline -axis. The excitation gap is of 18 meV and the bandwidth is about half of the gap. The band top energy has a weak modulation along the [100] direction, indicative of a small interchain coupling. The gap increases while the bandwidth decreases with increasing temperature, leading to a strong reduction in the available phase space for the triplons. As a result, the Lorentzian-type energy broadening becomes highly asymmetric as the temperature is raised. These results are associated with a strongly correlated state resulting from hard-core constraint and quasiparticle interactions. We consider these results to be not only evidence for strong correlations at finite temperatures in Na $_{2}$ Cu $_{2}$ TeO $_{6}$ , but also for the universality of the strongly correlated state in a broad range of quantum magnetic systems.

論文

The $^{59}$ Fe(n,) $^{60}$ Fe cross section from the surrogate ratio method and its effect on the $^{60}$ Fe nucleosynthesis

Yan, S. Q.*; Li, X. Y.*; 西尾勝久; Lugaro, M.*; Li, Z. H.*; 牧井宏之; Pignatari, M.*; Wang, Y. B.*; Orlandi, R.; 廣瀬健太郎; et al.

Astrophysical Journal, 919(2), p.84_1 - 84_7, 2021/10

https://doi.org/10.3847/1538-4357/ac12ce

被引用回数：5 パーセンタイル：33.27(Astronomy & Astrophysics)

The long-lived $^{60}$ Fe (with a half-life of 2.62 Myr) is a crucial diagnostic of active nucleosynthesis in the Milky Way galaxy and in supernovae near the solar system. The neutron-capture reaction $^{59}$ Fe(n,) $^{60}$ Fe on $^{59}$ Fe (half-life=44.5 days) is the key reaction for the production of $^{60}$ Fe in massive stars. This reaction cross section has been previously constrained by the Coulomb dissociation experiment, which offered partial constraint on the E1 -ray strength function but a negligible constraint on the M1 and E2 components. In this work, for the first time, we use the surrogate ratio method to experimentally determine the $^{59}$ Fe(n,) $^{60}$ Fe cross sections in which all the components are included. We derived a Maxwellian-averaged cross section of 27.53.5 mb at = 30 keV and 13.41.7 mb at = 90 keV, roughly 10%-20% higher than previous estimates. We analyzed the impact of our new reaction rates in nucleosynthesis models of massive stars and found that uncertainties in the production of $^{60}$ Fe from the $^{59}$ Fe(n,) $^{60}$ Fe rate are at most 25. We conclude that stellar physics uncertainties now play a major role in the accurate evaluation of the stellar production of $^{60}$ Fe.

論文

New -emitting isotope $^{214}$ U and abnormal enhancement of -particle clustering in lightest uranium isotopes

Zhang, Z. Y.*; Yang, H. B.*; Andreyev, A. N.; Liu, M. L.*; Ma, L.*; 他37名*

Physical Review Letters, 126(15), p.152502_1 - 152502_6, 2021/04

https://doi.org/10.1103/PhysRevLett.126.152502

被引用回数：85 パーセンタイル：97.79(Physics, Multidisciplinary)

A new -emitting isotope $^{214}$ U, produced by the fusion-evaporation reaction $^{182}$ W( $^{36}$ Ar,4n) $^{214}$ U, was identified by employing the gas-filled recoil separator SHANS and the recoil- correlation technique. More precise -decay properties of even-even nuclei $^{216,218}$ U were also measured in the reactions of $^{40}$ Ar, $^{40}$ Ca beams with $^{180,182,184}$ W targets. By combining the experimental data, improved -decay reduced widths $^{2}$ for the even-even Po-Pu nuclei in the vicinity of the magic neutron number = 126 are deduced. Their systematic trends are discussed in terms of the $_{it p}$ $_{it n}$ scheme in order to study the influence of proton-neutron interaction on decay in this region of nuclei. It is strikingly found that the reduced widths of $^{214,216}$ U are significantly enhanced by a factor of two as compared with the $_{it p}$ $_{it n}$ systematics for the 84 90 and 126 even-even nuclei. The abnormal enhancement is interpreted by the strong monopole interaction between the valence protons and neutrons occupying the 1 $_{7/2}$ and 1 $_{5/2}$ spin-orbit partner orbits, which is supported by the large-scale shell model calculation.

論文

Evidence for magnon-phonon coupling in the topological magnet Cu $_{3}$ TeO $_{6}$

Bao, S.*; Cai, Z.*; Si, W.*; Wang, W.*; Wang, X.*; Shangguan, Y.*; Ma, Z.*; Dong, Z.-Y.*; 梶本亮一; 池内和彦*; et al.

Physical Review B, 101(21), p.214419_1 - 214419_8, 2020/06

https://doi.org/10.1103/PhysRevB.101.214419

被引用回数：21 パーセンタイル：71.94(Materials Science, Multidisciplinary)

We perform thermodynamic and inelastic neutron scattering (INS) measurements to study the lattice dynamics (phonons) of a cubic collinear antiferromagnet Cu $_{3}$ TeO $_{6}$ which hosts topological spin excitations (magnons). While the specific heat and thermal conductivity results show that the thermal transport is dominated by phonons, the deviation of the thermal conductivity from a pure phononic model indicates that there is a strong coupling between magnons and phonons. In the INS measurements, we find a mode in the excitation spectra at 4.5 K, which exhibits a slight downward dispersion around the Brillouin zone center. This mode disappears above the Nel temperature and thus cannot be a phonon. Furthermore, the dispersion is distinct from that of a magnon. Instead, it can be explained by the magnon-polaron mode, collective excitations resulting from the hybridization between magnons and phonons. We consider the suppression of the thermal conductivity and emergence of the magnon-polaron mode to be evidence for magnon-phonon coupling in Cu $_{3}$ TeO $_{6}$ .

論文

Spin dynamics of a magnetic Weyl semimetal Sr $_{1-x}$ Mn $_{1-y}$ Sb $_{2}$

Cai, Z.*; Bao, S.*; Wang, W.*; Ma, Z.*; Dong, Z.-Y.*; Shangguan, Y.*; Wang, J.*; Ran, K.*; Li, S.*; 蒲沢和也*; et al.

Physical Review B, 101(13), p.134408_1 - 134408_10, 2020/04

AA2020-0050.pdf:5.09MB

https://doi.org/10.1103/PhysRevB.101.134408

被引用回数：7 パーセンタイル：34.47(Materials Science, Multidisciplinary)

ディラック物質は量子現象と共にキャリアの役割を探索するのに良い系で、磁気ワイル半金属のSr $_{1-x}$ Mn $_{1-y}$ Sb $_{2}$ はワイルフェルミオンとマグノンの関係を研究する良い舞台である。本研究では、Sr $_{1-x}$ Mn $_{1-y}$ Sb $_{2}$ の単結晶の中性子非弾性散乱実験を行い、磁性Mn層の分散は約76meVまで広がり、層間の分散は6meVの狭いバンド幅を持つことを見出した。また、これらの実験結果はハイゼンベルグ・スピンハミルトニアンを用いた線形スピン波理論によって再現可能である。本研究では、ワイルフェルミオンとマグノンが共存しているにもかかわらず、Sr $_{1-x}$ Mn $_{1-y}$ Sb $_{2}$ 中のワイルフェルミオンが磁気ダイナミクスに影響を与えているという明確な証拠は得られなかった。これは、ワイルフェルミオンとマグノンがSb層とMn層に別々に存在し、この擬二次元性による層間結合の弱さに起因するもの考えられる。

論文

Non-destructive analysis of samples with a complex geometry by NRTA

Ma, F.; Kopecky, S.*; Alaerts, G.*; 原田秀郎; Heyse, J.*; 北谷文人; Noguere, G.*; Paradela, C.*; alamon, L.*; Schillebeeckx, P.*; et al.

Journal of Analytical Atomic Spectrometry, 35(3), p.478 - 488, 2020/03

AA2019-0356.pdf:2.54MB

https://doi.org/10.1039/C9JA00342H

被引用回数：7 パーセンタイル：49.22(Chemistry, Analytical)

The use of Neutron Resonance Transmission Analysis to characterize homogeneous samples not fulfilling good transmission geometry conditions is discussed. Analytical expressions for such samples have been derived and implemented in the resonance shape analysis code REFIT. They were validated by experiments at the time-of-flight facility GELINA using a set of metallic natural copper samples. The expressions were used to derive sample characteristics by a least squares adjustment to experimental transmission data. In addition, the resonance parameters of Cu for energies below 6 keV, which are reported in the literature and recommended in evaluated data libraries, were verified. This research was implemented under the subsidiary for nuclear security promotion of MEXT.

論文

Shell structure of the neutron-rich isotopes $^{69,71,73}$ Co

Lokotko, T.*; Leblond, S.*; Lee, J.*; Doornenbal, P.*; Obertelli, A.*; Poves, A.*; Nowacki, F.*; 緒方一介*; 吉田数貴; Authelet, G.*; et al.

Physical Review C, 101(3), p.034314_1 - 034314_7, 2020/03

https://doi.org/10.1103/PhysRevC.101.034314

被引用回数：12 パーセンタイル：73.32(Physics, Nuclear)

中性子過剰核である $^{69,71,73}$ Coに対する()ノックアウト反応が理化学研究所RIBFで測定された。 coincidenceの方法で準位構造が決定され、測定された包括的断面積および排他的断面積から暫定的ではあるがスピン・パリティが決定された。殻模型計算との比較により、 $^{69,71,73}$ Coの低励起状態には球形核と変形核が共存することが示唆された。

論文

IRDFF-II; A New neutron metrology library

Trkov, A.*; Griffin, P. J.*; Simakov, S. P.*; Greenwood, L. R.*; Zolotarev, K. I.*; Capote, R.*; Aldama, D. L.*; Chechev, V.*; Destouches, C.*; Kahler, A. C.*; et al.

Nuclear Data Sheets, 163, p.1 - 108, 2020/01

https://doi.org/10.1016/j.nds.2019.12.001

被引用回数：136 パーセンタイル：99.75(Physics, Nuclear)

60MeVまでの核分裂炉、核融合炉の中性子計測のための核データであるIRDFF-IIが公開された。このライブラリは、(a)研究炉応用、(b)商業炉の安全性応用、(c)核融合材料開発のための損傷研究、をサポートしている。本論文は、ライブラリの内容、検証プロセスについて述べ、幅広い中性子場でのベンチマークデータを提供している。このライブラリは様々な応用のための中性子計測における国際的な基準データとなることが期待される。