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論文

A Systematic approach for the adequacy analysis of a set of experimental databases: Application in the framework of the ATRIUM activity

Baccou, J.*; Glantz, T.*; Ghione, A.*; Sargentini, L.*; Fillion, P.*; Damblin, G.*; Sueur, R.*; Iooss, B.*; Fang, J.*; Liu, J.*; et al.

Nuclear Engineering and Design, 421, p.113035_1 - 113035_16, 2024/05

In the Best-Estimate Plus Uncertainty (BEPU) framework, the use of best-estimate code requires to go through a Verification, Validation and Uncertainty Quantification process (VVUQ). The relevance of the experimental data in relation to the physical phenomena of interest in the VVUQ process is crucial. Adequacy analysis of selected experimental databases addresses this problem. The outcomes of the analysis can be used to select a subset of relevant experimental data, to encourage designing new experiments or to drop some experiments from a database because of their substantial lack of adequacy. The development of a specific transparent and reproducible approach to analyze the relevance of experimental data for VVUQ still remains open and is the topic of this contribution. In this paper, the concept of adequacy initially introduced in the OECD/NEA SAPIUM (Systematic APproach for model Input Uncertainty quantification Methodology) activity is formalized. It is defined through two key properties, called representativeness and completeness, that allows considering the multifactorial dimension of the adequacy problem. A new systematic approach is then proposed to analyze the adequacy of a set of experimental databases. It relies on the introduction of two sets of criteria to characterize representativeness and completeness and on the use of multi-criteria decision analysis method to perform the analysis. Finally, the approach is applied in the framework of the new OECD/NEA ATRIUM activity which includes a set of practical IUQ exercises in thermal-hydraulics to test the SAPIUM guideline in determining input uncertainties and forward propagating them on an application case. It allows evaluating the adequacy of eight experimental databases coming from the Super Moby-dick, Sozzi-Sutherland and Marviken experiments and identifying the most adequate ones.

論文

Crystal-liquid duality driven ultralow two-channel thermal conductivity in $$alpha$$-MgAgSb

Li, J.*; Li, X.*; Zhang, Y.*; Zhu, J.*; Zhao, E.*; 古府 麻衣子; 中島 健次; Avdeev, M.*; Liu, P.-F.*; Sui, J.*; et al.

Applied Physics Reviews (Internet), 11(1), p.011406_1 - 011406_8, 2024/03

 被引用回数:0 パーセンタイル:0.01(Physics, Applied)

The desire for intrinsically low lattice thermal conductivity ($$kappa_L$$) in thermoelectrics motivates numerous efforts on understanding the microscopic mechanisms of heat transport in solids. Here, based on theoretical calculations, we demonstrate that $$alpha$$-MgAgSb hosts low-energy localized phonon bands and avoided crossing of the rattler modes, which coincides with the inelastic neutron scattering result. Using the two-channel lattice dynamical approach, we find, besides the conventional contribution ($$sim$$70% at 300 K) from particlelike phonons propagating, the coherence contribution dominated by the wavelike tunneling of phonons accounts for $$sim$$30% of total $$kappa_L$$ at 300 K. By considering dual contributions, our calculated room-temperature $$kappa_L$$ of 0.64 Wm$$^{-1}$$K$$^{-1}$$ well agrees with the experimental value of 0.63 Wm$$^{-1}$$K$$^{-1}$$. More importantly, our computations give a nonstandard $$kappa_L propto T^{-0.61}$$ dependence, perfectly explaining the abnormal temperature-trend of $$sim T^{-0.57}$$ in experiment for $$alpha$$-MgAgSb. By molecular dynamics simulation, we reveal that the structure simultaneously has soft crystalline sublattices with the metavalent bonding and fluctuating liquid-like sublattices with thermally induced large amplitude vibrations. These diverse forms of chemical bonding arouse mixed part-crystal part-liquid state, scatter strongly heat-carrying phonons, and finally produce extremely low $$kappa_L$$. The fundamental research from this study will accelerate the design of ultralow-$$kappa_L$$ materials for energy-conversion applications.

論文

Chiral Dirac fermion in a collinear antiferromagnet

Zhang, A.*; Deng, K.*; Sheng, J.*; Liu, P.*; Kumar, S.*; 島田 賢也*; Jiang, Z.*; Liu, Z.*; Shen, D.*; Li, J.*; et al.

Chinese Physics Letters, 40(12), p.126101_1 - 126101_8, 2023/12

 被引用回数:1 パーセンタイル:0(Physics, Multidisciplinary)

In a Dirac semimetal, the massless Dirac fermion has zero chirality, leading to surface states connected adiabatically to a topologically trivial surface state as well as vanishing anomalous Hall effect. Recently, itis predicted that in the nonrelativistic limit of certain collinear antiferromagnets, there exists a type of chiral "Dirac-like" fermion, whose dispersion manifests four-fold degenerate crossing points formed by spin-degenerate linear bands, with topologically protected Fermi arcs. Here, by combining with neutron diffraction and first-principles calculations, we suggest a multidomain collinear antiferromagnetic configuration, rendering the existence of the Fermi-arc surface states induced by chiral Dirac-like fermions.

論文

Tetrahedral triple-Q magnetic ordering and large spontaneous Hall conductivity in the metallic triangular antiferromagnet Co$$_{1/3}$$TaS$$_{2}$$

Park, P.*; Cho, W.*; Kim, C.*; An, Y.*; Kang, Y.-G.*; Avdeev, M.*; Sibille, R.*; 飯田 一樹*; 梶本 亮一; Lee, K. H.*; et al.

Nature Communications (Internet), 14, p.8346_1 - 8346_9, 2023/12

 被引用回数:0 パーセンタイル:0(Multidisciplinary Sciences)

The triangular lattice antiferromagnet (TLAF) has been the standard paradigm of frustrated magnetism for several decades. The most common magnetic ordering in insulating TLAFs is the 120$$^{circ}$$ structure. However, a new triple-$$mathbf{Q}$$ chiral ordering can emerge in metallic TLAFs, representing the short wavelength limit of magnetic skyrmion crystals. We report the metallic TLAF Co$$_{1/3}$$TaS$$_{2}$$ as the first example of tetrahedral triple-$$mathbf{Q}$$ magnetic ordering with the associated topological Hall effect (non-zero $$sigma_{xy}(mathbf{H}=0)$$). We also present a theoretical framework that describes the emergence of this magnetic ground state, which is further supported by the electronic structure measured by angle-resolved photoemission spectroscopy. Additionally, our measurements of the inelastic neutron scattering cross section are consistent with the calculated dynamical structure factor of the tetrahedral triple-$$mathbf{Q}$$ state.

論文

A Predicted CRISPR-mediated symbiosis between uncultivated archaea

Esser, S. P.*; Rahlff, J.*; Zhao, W.*; Predl, M.*; Plewka, J.*; Sures, K.*; Wimmer, F.*; Lee, J.*; Adam, P. S.*; McGonigle, J.*; et al.

Nature Microbiology (Internet), 8(9), p.1619 - 1633, 2023/09

 被引用回数:2 パーセンタイル:79.73(Microbiology)

CRISPR-Cas systems defend prokaryotic cells from viruses, plasmids, and other mobile genetic elements. Capitalizing on multi-omics approaches, we show here that the CRISPR-Cas systems of uncultivated archaea also play an integral role in mitigating potentially detrimental interactions with episymbionts. A comprehensive analysis of CRISPR-Cas-based infection histories revealed that uncultivated deep-subsurface archaeal primary-producers defend themselves from archaeal episymbionts of the DPANN superphylum of archaea, some of which are known to fuse their membranes with their host. We show that host cells counter these attacks by deploying one of two CRISPR-Cas systems (type I-B and type III-A) to target and disrupt essential genes in the episymbiont. However, genome-scale modeling of metabolic interactions between two deep subsurface host-symbiont systems revealed that host cells also benefit from the symbionts via metabolic complementation. We speculate that populations of these uncultivated archaeal episymbionts are currently transitioning from a parasitic lifestyle to one of mutualism, as must have occurred in countless mutualistic systems known today. By expanding our analysis to thousands of archaeal genomes, we conclude that CRISPR-Cas mediated resistance to archaeal episymbiosis evolved independently in various archaeal lineages and may be a wide-spread evolutionary phenomenon.

論文

Tensile overload-induced texture effects on the fatigue resistance of a CoCrFeMnNi high-entropy alloy

Lam, T.-N.*; Chin, H.-H.*; Zhang, X.*; Feng, R.*; Wang, H.*; Chiang, C.-Y.*; Lee, S. Y.*; 川崎 卓郎; Harjo, S.; Liaw, P. K.*; et al.

Acta Materialia, 245, p.118585_1 - 118585_9, 2023/02

 被引用回数:8 パーセンタイル:80.32(Materials Science, Multidisciplinary)

The present study investigates the crystallographic-texture effects on the improved fatigue resistance in the CoCrFeMnNi high-entropy alloys (HEAs) with the full-size geometry of the ASTM Standards E647-99. We exploited X-ray nano-diffraction mapping to characterize the crystal-deformation levels ahead of the crack tip after stress unloading under both constant- and tensile overloaded-fatigue conditions. The crack-tip blunting-induced much higher deformation level was concentrated surrounding the crack-tip which delays the fatigue-crack growth immediately after a tensile overload. The predominant deformation texture orientation in the Paris regime was investigated, using electron backscatter diffraction and orientation distribution function analyses. The twinning formation-driven shear deformation gave rise to the development of the Goss-type texture within the plastic deformation regime under a tensile-overloaded-fatigue condition, which was attributed to enhance the crack deflection and thus the tensile induced crack-growth-retardation period in the CoCrFeMnNi HEA.

論文

Hybridized propagation of spin waves and surface acoustic waves in a multiferroic-ferromagnetic heterostructure

Chen, J.*; 山本 慧; Zhang, J.*; Ma, J.*; Wang, H.*; Sun, Y.*; Chen, M.*; Ma, J.*; Liu, S.*; Gao, P.*; et al.

Physical Review Applied (Internet), 19(2), p.024046_1 - 024046_9, 2023/02

 被引用回数:4 パーセンタイル:90.23(Physics, Applied)

Coherent coupling in magnon based hybrid system has many potential applications in quantum information processing. Magnons can propagate in magnetically ordered materials without any motion of electrons, offering a unique method to build low-power-consumption devices and information channels free of heat dissipation. In this article, we demonstrate the coherent propagation of hybridized modes between spin waves and Love surface acoustic waves in a multiferroic BiFeO$$_{3}$$ and ferromagnetic La$$_{0.67}$$Sr$$_{0.33}$$MnO$$_{3}$$ based heterostructure. The magneto-elastic coupling enables a giant enhancement of strength of the hybridized mode by a factor of 26 compared to that of the pure spin waves. A short wavelength down to 250 nm is demonstrated for the hybridized mode, which is desirable for nanoscale acousto-magnonic applications. Our combined experimental and theoretical analyses represent an important step towards the coherent control in hybrid magnonics, which may inspire the study of magnon-phonon hybrid systems for coherent information processing and manipulation.

論文

Experimental evidence for the significance of optical phonons in thermal transport of tin monosulfide

Wu, P.*; 村井 直樹; Li, T.*; 梶本 亮一; 中村 充孝; 古府 麻衣子; 中島 健次; Xia, K.*; Peng, K.*; Zhang, Y.*; et al.

New Journal of Physics (Internet), 25(1), p.013032_1 - 013032_11, 2023/01

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

The understanding of the lattice dynamics is essential for engineering the thermal transport properties in quantum materials. Based on the canonical point of view, acoustic phonons are believed to be the principal thermal carriers in heat flow. Here, in this work, optical phonons are elucidated to play a pivotal role in determining the lattice thermal conductivity in thermoelectric material SnS by using the state-of-the-art inelastic neutron scattering technique combined with first-principles calculations. Additionally, in contrast to acoustic phonons, optical phonons are observed to exhibit pronounced softening and broadening with temperature. Our observations not only shed light on the significance of the optical phonons in thermal transport but also provide a vital clue to suppress the propagation of optical phonons to optimize the thermoelectric performance of SnS.

論文

Ten years of warming increased plant-derived carbon accumulation in an East Asian monsoon forest

Zhang, J.*; Kuang, L.*; Mou, Z.*; 近藤 俊明*; 小嵐 淳; 安藤 麻里子; Li, Y.*; Tang, X.*; Wang, Y.-P.*; Pe$~n$uelas, J.*; et al.

Plant and Soil, 481(1-2), p.349 - 365, 2022/12

 被引用回数:3 パーセンタイル:22.98(Agronomy)

Soil warming effects on soil organic carbon (SOC) decomposition and stabilization are highly variable, and the underlying mechanisms are poorly understood. In this study, concentration, stability (dissolved, particle and mineral-associated SOC), and source (plant-derived and microbial-derived) of SOC, soil microbial community composition, and enzyme activities were studied in a 10-year soil warming field experiment in an East Asian monsoon forest. The results showed that 10-year soil warming significantly enhanced SOC in the top 0-10 cm soil. The increased SOC induced by warming was mainly derived from plants with lignin markers, accompanied by a decrease in microbial-derived SOC. This highlights an urgent need for a better understanding of how the contrasting effects of plant- and microbial-derived C mediate the response of the SOC pool to warming across different biomes.

論文

First observation of the decay of the 13/2$$^+$$ isomer in $$^{183}$$Hg and $$B$$(${it M}$2) systematics of neutron transitions across the nuclear chart

Huang, H.*; Zhang, W. Q.*; Andreyev, A. N.; Liu, Z.*; Seweryniak, D.*; Li, Z. H.*; Guo, C. Y.*; Barzakh, A. E.*; Van Duppen, P.*; Andel, B.*; et al.

Physics Letters B, 833, p.137345_1 - 137345_8, 2022/10

 被引用回数:0 パーセンタイル:0.02(Astronomy & Astrophysics)

The decay of the 13/2$$^+$$ isomeric state in $$^{183}$$Hg was observed for the first time following the $$alpha$$ decay of the 13/2$$^+$$ isomer in $$^{187}$$Pb produced in the $$^{142}$$Nd$$(^{50}$$Cr$$, 2p3n)$$ reaction. Using $$alpha$$-$$gamma$$ delayed coincidence measurements, the half-life of this isomer was measured to be 290(30) $$mu$$s. This isomer is proposed to deexcite by an unobserved low-energy $$M$$2 transition to the known 9/2$$^-$$ member of a strongly prolate-deformed 7/2$$^-$$[514] band, followed by a 105-keV $$M$$1 transition to the bandhead. A lower limit of B($$M$$2)$$geq$$0.018 W.u. was deduced for the unobserved transition. The presumed retardation is proposed to be due to the notable shape change between the initial, nearly spherical, and the final, strongly deformed, states. A similar scenario is also considered for the 13/2$$^+$$ isomer in $$^{181}$$Hg, suggesting both are cases of shape isomers. The B($$M$$2) systematics of neutron transitions across the nuclear chart is discussed.

論文

Synergistic hybrid electrocatalysts of platinum alloy and single-atom platinum for an efficient and durable oxygen reduction reaction

Liu, B.*; Feng, R.*; Busch, M.*; Wang, S.*; Wu, H.*; Liu, P.*; Gu, J.*; Bahadoran, A.*; 松村 大樹; 辻 卓也; et al.

ACS Nano, 16(9), p.14121 - 14133, 2022/09

 被引用回数:49 パーセンタイル:98.33(Chemistry, Multidisciplinary)

Pt single-atom materials possess an ideal atom economy but suffer from limited intrinsic activity and side reaction of producing H$$_{2}$$O$$_{2}$$ in catalyzing the oxygen reduction reaction (ORR). Here, we demonstrate that anchoring platinum alloys on single-atom Pt-decorated carbon (Pt- SAC) surmounts their inherent deficiencies, thereby enabling a complete four-electron ORR pathway catalysis with high efficiency and durability. Pt$$_{3}$$Co@Pt-SAC demonstrates an exceptional mass and specific activities 1 order of magnitude higher than those of commercial Pt/C. They are durable throughout 50000 cycles, showing only a 10 mV decay in halfwave potential. The superior durability is attributed to the shielding effect of the Pt-SAC coating, which significantly mitigates the dissolution of Pt$$_{3}$$Co cores.

論文

Transport model comparison studies of intermediate-energy heavy-ion collisions

Walter, H.*; Colonna, M.*; Cozma, D.*; Danielewicz, P.*; Ko, C. M.*; Kumar, R.*; 小野 章*; Tsang, M. Y. B*; Xu, J.*; Zhang, Y.-X.*; et al.

Progress in Particle and Nuclear Physics, 125, p.103962_1 - 103962_90, 2022/07

 被引用回数:48 パーセンタイル:96.94(Physics, Nuclear)

原子核-原子核衝突や原子核の状態方程式の研究において、反応計算モデルは重要なツールとなり、世界中で開発が進んでいる。本論文は、原子力機構のJQMD-2.0を含め、現在開発中の複数のコード開発者の協力により、これらコードを同じ条件で比較することで共通点や差異を明らかにしたプロジェクトTransport Model Evaluation Project (TMEP)を総括したものである。参加したコードはBoltzmann-Uehling-Uhlenbeck(BUU)法に基づく13のコードと、Quantum Molecular Dynamics (QMD)法に基づく12のコードであった。プロジェクトでは、Au原子核同士を衝突させてその終状態を観測する現実的な計算や、一辺が640nmの箱に核子を詰めて時間発展させる仮想的な計算を行った。その結果、BUU法コードとQMD法コードは計算原理が異なるため、計算の設定に関係なく系統的な差異が生じることが明らかになった。その一方で、同じ方法を採用するコード間の比較では、時間発展を細かく計算することでコード間の差は埋まっていき、一定の収束値を持つことが示された。この結果は今後開発される同分野のコードのベンチマークデータとして有用なものであるだけでなく、原子核基礎物理学の実験や理論研究の標準的な指針としても役に立つことが期待される。

論文

Status of the uncertainty quantification for severe accident sequences of different NPP-designs in the frame of the H-2020 project MUSA

Brumm, S.*; Gabrielli, F.*; Sanchez-Espinoza, V.*; Groudev, P.*; Ou, P.*; Zhang, W.*; Malkhasyan, A.*; Bocanegra, R.*; Herranz, L. E.*; Berda$"i$, M.*; et al.

Proceedings of 10th European Review Meeting on Severe Accident Research (ERMSAR 2022) (Internet), 13 Pages, 2022/05

The current HORIZON-2020 project on "Management and Uncertainties of Severe Accidents (MUSA)" aims at applying Uncertainty Quantification (UQ) in the modeling of Severe Accidents (SA), particularly in predicting the radiological source term of mitigated and unmitigated accident scenarios. Within its application part, the project is devoted to the uncertainty quantification of different severe accident codes when predicting the radiological source term of selected severe accident sequences of different nuclear power plant designs, e.g. PWR, VVER, and BWR. Key steps for this investigation are, (a) the selection of severe accident sequences for each reactor design, (b) the development of a reference input model for the specific design and SA-code, (c) the selection of a list of uncertain model parameters to be investigated, (d) the choice of an UQ-tool e.g. DAKOTA, SUSA, URANIE, etc., (e) the definition of the figures of merit for the UA-analysis, (f) the performance of the simulations with the SA-codes, and, (g) the statistical evaluation of the results using the capabilities, i.e. methods and tools offered by the UQ-tools. This paper describes the project status of the UQ of different SA codes for the selected SA sequences, and the technical challenges and lessons learnt from the preparatory and exploratory investigations performed.

論文

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 & Technology, 99, p.55 - 60, 2022/02

 被引用回数:5 パーセンタイル:41.35(Materials Science, Multidisciplinary)

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。

論文

Modelling and simulation of the source term for a sodium cooled fast reactor under hypothetical severe accident conditions; Final report of a coordinated research project

Arokiaswamy, J. A.*; Batra, C.*; Chang, J. E.*; Garcia, M.*; Herranz, L. E.*; Klimonov, I. A.*; Kriventsev, V.*; Li, S.*; Liegeard, C.*; Mahanes, J.*; et al.

IAEA-TECDOC-2006, 380 Pages, 2022/00

IAEAの共同研究プロジェクト「シビアアクシデント条件下におけるプロトタイプナトリウム冷却高速炉からの放射性物質の放出」は、シビアアクシデント条件下における、リファレンスとなるナトリウム冷却高速炉の施設内における放射性物質および燃料粒子の存在量の、異なる時間スケールにおける現実的な数値シミュレーションを目的として実施された。解析のスコープは3つに分割され、3つのワークパッケージ(WP)として定義された:(1)炉内ソースターム評価、(2)一次系/格納容器系境界のソースターム評価、および(3)格納容器内の現象分析。WP-1の参加機関の結果を比較すると、希ガスおよび放射性セシウムの放出割合、およびカバーガスへの放射性核種の放出割合はよく一致した。共通の圧力履歴を用いたWP-2の解析では、各機関の解析結果はよく一致し、いずれの機関の解析手法も同程度の精度を有することが示された。先行するWPにおける解析と分離するため、放出割合をあらかじめ設定したスタンドアロンケースがWP-3にて定義された。WP-3の全参加機関によるスタンドアロンケースの解析結果は全般的に一致した。

論文

Crystalline fully carboxylated polyacetylene obtained under high pressure as a Li-ion battery anode material

Wang, X.*; Tang, X.*; Zhang, P.*; Wang, Y.*; Gao, D.*; Liu, J.*; Hui, K.*; Wang, Y.*; Dong, X.*; 服部 高典; et al.

Journal of Physical Chemistry Letters (Internet), 12(50), p.12055 - 12061, 2021/12

 被引用回数:6 パーセンタイル:44.89(Chemistry, Physical)

置換ポリアセチレンは、ポリアセチレン骨格の化学的安定性,物性,付加機能の向上が期待されるが、その多様性は非常に限られている。今回我々は、固体のアセチレンジカルボン酸に外圧を加えることにより、従来の方法では合成が非常に困難であったトランス-ポリアセチレン骨格上のすべての炭素がカルボキシル基に結合した結晶性のポリ-ジカルボキシルアセチレンができることを報告する。重合は、水素結合を利用したトポケミカル反応であった。このユニークな構造は、カルボニル基の極めて高い含有量とポリアセチレン骨格の高い導電性を組み合わせたもので、リチウムイオン電池(LIB)負極として高い比容量と優れたサイクル/レート性能を示す。我々は、完全に機能化された結晶性ポリアセチレンを紹介し、高分子LIB材料や活性基を多く含む高分子材料合成のために圧力重合が有力な方法であることを提案する。

論文

Long decay length of magnon-polarons in BiFeO$$_{3}$$/La$$_{0.67}$$Sr$$_{0.33}$$MnO$$_{3}$$ heterostructures

Zhang, J.*; Chen, M.*; Chen, J.*; 山本 慧; Wang, H.*; Hamdi, M.*; Sun, Y.*; Wagner, K.*; He, W.*; Zhang, Y.*; et al.

Nature Communications (Internet), 12, p.7258_1 - 7258_8, 2021/12

 被引用回数:14 パーセンタイル:77.64(Multidisciplinary Sciences)

Magnons can transfer information in metals and insulators without Joule heating, and therefore are promising for low-power computation. The on-chip magnonics however suffers from high losses due to limited magnon decay length. In metallic thin films, it is typically on the tens of micrometre length scale. Here, we demonstrate an ultra-long magnon decay length of up to one millimetre in multiferroic/ferromagnetic BiFeO$$_{3}$$(BFO)/La$$_{0.67}$$Sr$$_{0.33}$$MnO$$_{3}$$ (LSMO) heterostructures at room temperature. This decay length is attributed to a magnon-phonon hybridization and is more than two orders of magnitude longer than that of bare metallic LSMO. The long-distance modes have high group velocities of 2.5 km$$^{-1}$$ as detected by time-resolved Brillouin light scattering. Numerical simulations suggest that magnetoelastic coupling via the BFO/LSMO interface hybridizes phonons in BFO with magnons in LSMO. Our results provide a solution to the long-standing issue on magnon decay lengths in metallic magnets and advance the bourgeoning field of hybrid magnonics.

論文

Paramagnetic spin Hall magnetoresistance

大柳 洸一*; Gomez-Perez, J. M.*; Zhang, X.-P.*; 吉川 貴史*; Chen, Y.*; Sagasta, E.*; Chuvilin, A.*; Hueso, L. E.*; Golovach, V. N.*; Sebastian Bergeret, F.*; et al.

Physical Review B, 104(13), p.134428_1 - 134428_14, 2021/10

 被引用回数:14 パーセンタイル:77.64(Materials Science, Multidisciplinary)

We report the observation of the spin Hall magnetoresistance (SMR) in a paramagnetic insulator. By measuring the transverse resistance in a Pt/Gd$$_3$$Ga$$_5$$O$$_{12}$$ (GGG) system at low temperatures, paramagnetic SMR is found to appear with an intensity that increases with the magnetic field aligning GGG's spins. The observed effect is well supported by a microscopic SMR theory, which provides the parameters governing the spin transport at the interface. Our findings clarify the mechanism of spin exchange at a Pt/GGG interface, and demonstrate tunable spin-transfer torque through the field-induced magnetization of GGG. In this regard, paramagnetic insulators offer a key property for future spintronic devices.

論文

Phase transition and chemical reactivity of 1H-tetrazole under high pressure up to 100 GPa

Gao, D.*; Tang, X.*; Wang, X.*; Yang, X.*; Zhang, P.*; Che, G.*; Han, J.*; 服部 高典; Wang, Y.*; Dong, X.*; et al.

Physical Chemistry Chemical Physics, 23(35), p.19503 - 19510, 2021/09

 被引用回数:4 パーセンタイル:36.54(Chemistry, Physical)

窒素に富む分子の圧力有機相転移や重合は、環境にやさしい高エネルギー密度材料の開発にとって非常に重要であるため、広く注目されている。本論文では、その場ラマン,IR,X線回折,中性子回折、および理論計算をもちい、100GPaまでの1H-テトラゾールの相転移挙動と化学反応の研究を紹介する。2.6GPa以上での相転移が確認され、その高圧構造は、以前に報告されたユニットセル内に2つの分子をもつものではなく、1つの分子をものであることが分かった。1H-テトラゾールは、おそらく窒素-窒素結合ではなく炭素-窒素結合により、100GPa以下で可逆的に重合する。私たちの研究は、1H-テトラゾールの高圧相の構造モデルを更新し、もっともらしい分子間結合の経路を初めて提示した。これにより、窒素に富む化合物の相転移と化学反応の理解が進み、新しい高エネルギー密度材料の設計に役立つと考えられる。

論文

Expansion of agriculture in northern cold-climate regions; A Cross-sectoral perspective on opportunities and challenges

Unc, A.*; Altdorff, D.*; Abakumov, E.*; Adl, S.*; Baldursson, S.*; Bechtold, M.*; Cattani, D. J.*; Firbank, L. G.*; Grand, S.*; Gudjonsdottir, M.*; et al.

Frontiers in Sustainable Food Systems (Internet), 5, p.663448_1 - 663448_11, 2021/07

 被引用回数:33 パーセンタイル:94.29(Food Science & Technology)

本レビュー論文では、関連分野を研究する科学者の意識調査と既存文献の調査を実施し、地球温暖化の加速が寒冷な北方地域を地域および世界の農業セクター拡大にとってますます魅力的なターゲットにしていることを明らかにした。ただし、こうした活動の持続可能な長期的発展は、信頼性のある関連知見に対し全てのステークホルダーが容易にアクセスできる場合にのみ実現できる、という共通認識があることも明らかになった。特に、北方地域における農業の拡大は、温室効果ガス収支や生物多様性、生態系サービスに対し、負の影響をもたらす傾向にあることが明らかになってきている。以上より、寒冷な北方地域における農業の拡大と強化は、社会的な向上とニュートラルな環境影響とを両立できる計画の下で遂行される必要がある。

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