Quantum critical behavior of the hyperkagome magnet MnCoSi

山内 宏樹; Sari, D. P.*; 安井 幸夫*; 坂倉 輝俊*; 木村 宏之*; 中尾 朗子*; 大原 高志; 本田 孝志*; 樹神 克明; 井川 直樹; et al.

Physical Review Research (Internet), 6(1), p.013144_1 - 013144_9, 2024/02

https://doi.org/10.1103/PhysRevResearch.6.013144

-Mn-type family alloys Mn have three-dimensional antiferromagnetic (AFM) corner-shared triangular network. The antiferromagnet MnRhSi shows magnetic short-range order (SRO) over a wide temperature range of approximately 500 K above the Nel temperature = 190 K. MnCoSi has the smallest lattice parameter and the lowest in the family compounds. The quantum critical point (QCP) from AFM to the quantum paramagnetic state is expected near a cubic lattice parameter of 6.15 of MnCoSi is only 140 K, quantum critical behavior is observed in MnCoSi as the enhancement of the electronic specific heat coefficient . We study how the magnetic SRO appears in MnCoSi by using neutron scattering, SR, and physical property measurements. The experimental results show that the neutron scattering intensity of the magnetic SRO does not change much regardless of the suppressed magnetic moment in the long-range magnetic ordered state compared to those of MnRhSi. The initial asymmetry drop ratio of SR above becomes small, and the magnetic SRO temperature is suppressed to 240 K. The results suggest that the MnCoSi is close to the QCP in the Mn system.

Spiral spin cluster in the hyperkagome antiferromagnet MnRhSi

社本 真一; 山内 宏樹; 飯田 一樹*; 池内 和彦*; Hall, A. E.*; Chen, Y.-S.*; Lee, M. K.*; Balakrishnan, G.*; Chang, L.-J.*

Communications Physics (Internet), 6, p.248_1 - 248_6, 2023/09

https://doi.org/10.1038/s42005-023-01363-1

MnRhSi単結晶の中性子散乱測定により、局所スピン相関秩序がらせん構造を持つことがわかった。磁気クラスター形成の起源の可能性を、リフシッツ不変量とグリフィス相の観点から議論し、CoZnMnの室温スキルミオン相とMnの非フェルミ液体挙動と比較した。

Si-addition contributes to overcoming the strength-ductility trade-off in high-entropy alloys

Wei, D.*; Gong, W.; 都留 智仁; Lobzenko, I.; Li, X.*; Harjo, S.; 川崎 卓郎; Do, H.-S.*; Bae, J. W.*; Wagner, C.*; et al.

International Journal of Plasticity, 159, p.103443_1 - 103443_18, 2022/12

https://doi.org/10.1016/j.ijplas.2022.103443

Face-centered cubic single-phase high-entropy alloys (HEAs) containing multi-principal transition metals have attracted significant attention, exhibiting an unprecedented combination of strength and ductility owing to their low stacking fault energy (SFE) and large misfit parameter that creates severe local lattice distortion. Increasing both strength and ductility further is challenging. In the present study, we demonstrate via meticulous experiments that the CoCrFeNi HEA with the addition of the substitutional metalloid Si can retain a single-phase FCC structure while its yield strength (up to 65%), ultimate strength (up to 34%), and ductility (up to 15%) are simultaneously increased, owing to a synthetical effect of the enhanced solid solution strengthening and a reduced SFE. The dislocation behaviors and plastic deformation mechanisms were tuned by the addition of Si, which improves the strain hardening and tensile ductility. The present study provides new strategies for enhancing HEA performance by targeted metalloid additions.

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, 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.

Soft, skin-interfaced microfluidic systems with integrated immunoassays, fluorometric sensors, and impedance measurement capabilities

Kim, S.*; Lee, B.*; Reeder, J. T.*; Seo, S. H.*; Lee, S.-U.*; Hourlier-Fargette, A.*; Shin, J.*; 関根 由莉奈; Jeong, H.*; Oh, Y. S.*; et al.

Proceedings of the National Academy of Sciences of the United States of America, 117(45), p.27906 - 27915, 2020/11

https://doi.org/10.1073/pnas.2012700117

本研究では、汗のコルチゾール分析のための流動イムノアッセイ、グルコースとアスコルビン酸(ビタミンC)分析のための蛍光測定イメージング、および電極を使用した発汗速度のデジタルトラッキングを組み合わせた、ワイヤレス,バッテリー不要の皮膚インターフェースマイクロ流体システムを実現した。運動している被験者を対象とした体系的なテストにより、本開発デバイスが物理的ストレスと生化学的相関を追跡可能であることが示された。

Signatures of the vortical quark-gluon plasma in hadron yields

田屋 英俊*; Park, A.*; Cho, S.*; Gubler, P.; 服部 恒一*; Hong, J.*; Huang, X.-G.*; Lee, S. H.*; 門内 明彦*; 大西 明*; et al.

Physical Review C, 102(2), p.021901_1 - 021901_6, 2020/08

AA2020-0306.pdf:0.47MB

https://doi.org/10.1103/PhysRevC.102.021901

We investigate the hadron production from the vortical quark-gluon plasma created in heavy-ion collisions. Based on the quark-coalescence and statistical hadronization models, we show that total hadron yields summed over the spin components are enhanced by the local vorticity with quadratic dependence. The enhancement factor amounts to be a few percent and may be detectable within current experimental sensitivities. We also show that the effect is stronger for hadrons with larger spin, and thus propose a new signature of the local vorticity, which may be detected by the yield ratio of distinct hadron species having different spins such as and . The vorticity dependence of hadron yields seems robust, with consistent predictions in both of the hadron production mechanisms for reasonable values of the vorticity strength estimated for heavy-ion collisions.

Surface coverage dependence of spin-to-charge current across Pt/MoS/YFeO layers via longitudinal spin Seebeck effect

Lee, W.-Y.*; Park, N.-W.*; Kang, M.-S.*; Kim, G.-S.*; Jang, H. W.*; 齊藤 英治; Lee, S.-K.*

Journal of Physical Chemistry Letters (Internet), 11(13), p.5338 - 5344, 2020/07

https://doi.org/10.1021/acs.jpclett.0c01502

The voltage induced by the inverse spin Hall effect (ISHE) is affected by several factors, including the spin Hall angle of the normal metal (NM), the quality and magnetic properties of the ferromagnetic material (FM), and the interface conditions between the NM and FM bilayers in longitudinal spin Seebeck effect (LSSE) measurement. Specifically, the interface conditions in NM/FM systems via LSSE devices play a crucial role in determining the efficiency of spin current injection into the NM layer. In this letter, we report a new approach to controlling the efficiency of spin current injection into a Pt layer across a Pt/YFeO (YIG) interface by surface coverage of the intermediate layer. A continuous, large-area multilayer molybdenum dichalcogenide (MoS) thin film grown by chemical vapor deposition is inserted between the Pt and YIG layers in the LSSE configuration. We found that, when the large-area multilayer MoS film was present, the measured ISHE-induced voltage and theoretically calculated spin current in the Pt/MoS/YIG trilayer increased by 510% and 470%, respectively, compared to those of a Pt/YIG bilayer. The induced voltage and spin current were very sensitive to the surface conductance, which was affected by the surface coverage of the multilayer MoS films in the LSSE measurement. Furthermore, the theoretically calculated spin current and spin mixing conductance in the trilayer geometry are in qualitatively good agreement with the experimental observations. These measurements enable us to explain the effect of the interface conditions on the spin Seebeck effect in spin transport.

A Review of separation processes proposed for advanced fuel cycles based on technology readiness level assessments

Baron, P.*; Cornet, S. M.*; Collins, E. D.*; DeAngelis, G.*; Del Cul, G.*; Fedorov, Y.*; Glatz, J. P.*; Ignatiev, V.*; 井上 正*; Khaperskaya, A.*; et al.

Progress in Nuclear Energy, 117, p.103091_1 - 103091_24, 2019/11

https://doi.org/10.1016/j.pnucene.2019.103091

本論文では、将来のクローズド燃料サイクルにおける使用済燃料のための分離プロセスに対する国際的リビューの結果が、技術成熟度評価の結果ととともに示されている。本研究は、ORCD/NEAで組織された燃料リサイクル化学に関する専門家グループによって実施されたものである。本研究の特徴的な点は、分離プロセスを使用済燃料中の分離対象元素(ウラン, ウラン-プルトニウム, マイナーアクチノイド, 発熱性元素等)別の分離階層により区分けして評価したことであり、これに使用済燃料の前処理プロセスの評価を加えている。分離プロセスとしては湿式プロセスと乾式プロセスの両者をカバーしている。

Nuclear structure of Ni from the (,) reaction

Elekes, Z.*; Kripk, *; Sohler, D.*; Sieja, K.*; 緒方 一介*; 吉田 数貴; Doornenbal, P.*; Obertelli, A.*; Authelet, G.*; 馬場 秀忠*; et al.

Physical Review C, 99(1), p.014312_1 - 014312_7, 2019/01

https://doi.org/10.1103/PhysRevC.99.014312

(,)反応によるNiの核構造の探索実験を行った。Lenzi, Nowacki, Poves, Sieja相互作用を用いた殻模型計算では実験結果を説明しうる陽子空孔状態が得られており、理論的な断面積計算は実験値とよい一致を与えた。実験で得られたすべての状態を理論的に一意に決定することはできなかったが、過去の実験結果と同様にNi同位体でのZ = 28の大きなshell gapを示す結果が得られた。

Overall approaches and experiences of first-time participants in the Nuclear Forensics International Technical Working Group's Fourth Collaborative Material Exercise (CMX-4)

Ho, D. M. L.*; Nelwamondo, A. N.*; 大久保 綾子; Ramebck, H.*; Song, K.*; Han, S.-H.*; Hancke, J. J.*; Holmgren, S.*; Jonsson, S.*; 片岡 修; et al.

Journal of Radioanalytical and Nuclear Chemistry, 315(2), p.353 - 363, 2018/02

https://doi.org/10.1007/s10967-017-5677-0

国際核鑑識作業グループが主催する第4回核鑑識共同試料分析演習には、過去最大の17か国からの参加があり、このうち7か国は初めての参加であった。本稿では、演習に初めて参加した5か国のラボラトリが、演習で実施した分析試料の準備および分析内容について情報を共有した。核鑑識共同試料分析演習は、各ラボラトリで確立した分析法のテスト、他の目的で確立した方法の核鑑識への適用化、分析技術の修練に非常に有用であることが確認された。また、演習実施後に開催されたレビュー会合によって、核鑑識シグネチャとその解釈に関する理解を深めることができた。