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論文

Direct observation of topological magnon polarons in a multiferroic material

Bao, S.*; Gu, Z.-L.*; Shangguan, Y.*; Huang, Z.*; Liao, J.*; Zhao, X.*; Zhang, B.*; Dong, Z.-Y.*; Wang, W.*; 梶本亮一; et al.

Nature Communications (Internet), 14, p.6093_1 - 6093_9, 2023/09

https://doi.org/10.1038/s41467-023-41791-9

被引用回数：1 パーセンタイル：61.99(Multidisciplinary Sciences)

Magnon polarons are novel elementary excitations possessing hybrid magnonic and phononic signatures, and are responsible for many exotic spintronic and magnonic phenomena. Despite long-term sustained experimental efforts in chasing for magnon polarons, direct spectroscopic evidence of their existence is hardly observed. Here, we report the direct observation of magnon polarons using neutron spectroscopy on a multiferroic Fe $_{2}$ Mo $_{3}$ O $_{8}$ possessing strong magnon-phonon coupling. Specifically, below the magnetic ordering temperature, a gap opens at the nominal intersection of the original magnon and phonon bands, leading to two separated magnon-polaron bands. Each of the bands undergoes mixing, interconverting and reversing between its magnonic and phononic components. We attribute the formation of magnon polarons to the strong magnon-phonon coupling induced by Dzyaloshinskii-Moriya interaction. Intriguingly, we find that the band-inverted magnon polarons are topologically nontrivial. These results uncover exotic elementary excitations arising from the magnon-phonon coupling, and offer a new route to topological states by considering hybridizations between different types of fundamental excitations.

論文

Magnetic properties and electronic configurations of Mn ions in the diluted magnetic semiconductor Ba $_{1-x}$ K(Zn $_{1-y}$ Mn)As studied by X-ray magnetic circular dichroism and resonant inelastic X-ray scattering

鈴木博人*; Zhao, G.*; 岡本淳*; 坂本祥哉*; Chen, Z.-Y.*; 野中洋亮*; 芝田悟朗; Zhao, K.*; Chen, B.*; Wu, W.-B.*; et al.

Journal of the Physical Society of Japan, 91(6), p.064710_1 - 064710_5, 2022/06

https://doi.org/10.7566/JPSJ.91.064710

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

The magnetic properties and the electronic excitations of the new diluted magnetic semiconductor Ba $_{1-x}$ K(Zn $_{1-y}$ Mn)As have been studied by X-ray magnetic circular dichroism (XMCD) and resonant inelastic X-ray scattering (RIXS). The sum rule analysis of the XMCD spectra indicates that the Mn atoms are in the high-spin configurations of , whereas the presence of competing ferromagnetic and antiferromagnetic interactions between the Mn ions reduces the net spin moment. Based on a comparison of the RIXS line shapes with those of Ga $_{1-x}$ MnAs, it is concluded that the ground state of Mn in Ba $_{1-x}$ K(Zn $_{1-y}$ Mn)As consists of both the $3d^5 underline{L}$ and electron configurations.

論文

Field-tuned magnetic structure and phase diagram of the honeycomb magnet YbCl

Hao, Y. Q.*; Wo, H. L.*; Gu, Y. M.*; Zhang, X. W.*; Gu, Y. Q.*; Zheng, S. Y.*; Zhao, Y.*; Xu, G. Y.*; Lynn, J. W.*; 中島健次; et al.

Science China; Physics, Mechanics & Astronomy, 64(3), p.237411_1 - 237411_6, 2021/03

https://doi.org/10.1007/s11433-020-1626-3

被引用回数：6 パーセンタイル：61.42(Physics, Multidisciplinary)

We report thermodynamic and neutron diffraction measurements on the magnetic ordering properties of the honeycomb lattice magnet YbCl. We find YbCl exhibits a Nel type long-range magnetic order at the wavevector (0, 0, 0) below T = 600 mK. This magnetic order is associated with a small sharp peak in heat capacity and most magnetic entropy release occurs above the magnetic ordering temperature. The magnetic moment lies in-plane, parallel to the monoclinic a-axis, whose magnitude m $_{rm Yb}$ = 0.86(3) is considerably smaller than the expected fully ordered moment of 2.24 for the doublet crystal-field ground state. The magnetic ordering moment gradually increases with increasing magnetic field perpendicular to the ab-plane, reaching a maximum value of 1.6(2) at 4 T, before it is completely suppressed above 9 T. These results indicate the presence of strong quantum fluctuations in YbCl.

論文

Coordination number regulation of molybdenum single-atom nanozyme peroxidase-like specificity

Wang, Y.*; Jia, G.*; Cui, X.*; Zhao, X.*; Zhang, Q.*; Gu, L.*; Zheng, L.*; Li, L. H.*; Wu, Q.*; Singh, D. J.*; et al.

Chem, 7(2), p.436 - 449, 2021/02

https://doi.org/10.1016/j.chempr.2020.10.023

被引用回数：194 パーセンタイル：99.8(Chemistry, Multidisciplinary)

Nanozymes are promising alternatives to natural enzymes, but their use remains limited owing to poor specificity. Overcoming this is extremely challenging due to the intrinsic structural complexity of these systems. We report theoretical design and experimental realization of a series of heterogeneous molybdenum single-atom nanozymes (named Mo $_{rm{SA}}$ -N $_{x}$ -C), wherein we find that the peroxidase-like specificity is well regulated by the coordination numbers of single Mo sites. The resulting Mo $_{rm{SA}}$ -N $_{3}$ -C catalyst shows exclusive peroxidase-like behavior. It achieves this behavior via a homolytic pathway, whereas Mo $_{rm{SA}}$ -N $_{2}$ -C and Mo $_{rm{SA}}$ -N $_{4}$ -C catalysts have a different heterolytic pathway. The mechanism of this coordination-number-dependent enzymatic specificity is attributed to geometrical structure differences and orientation relationships of the frontier molecular orbitals.

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

Li(Cd,Mn)P; A New cadmium based diluted ferromagnetic semiconductor with independent spin & charge doping

Han, W.*; Chen, B. J.*; Gu, B.*; 前川禎通*; 他14名*

Scientific Reports (Internet), 9, p.7490_1 - 7490_6, 2019/05

https://doi.org/10.1038/s41598-019-43754-x

被引用回数：9 パーセンタイル：41.92(Multidisciplinary Sciences)

We report a new diluted ferromagnetic semiconductor Li $_{1+y}$ (Cd,Mn)P, wherein carrier is doped via excess Li while spin is doped by isovalence substitution of Mn $^{2+}$ into Cd $^{2+}$ . The extended Cd 4-orbitals lead to more itinerant characters of Li $_{1+y}$ (Cd,Mn)P than that of analogous Li $_{1+y}$ (Zn,Mn)P. A higher Curie temperature of 45 K than that for Li $_{1+y}$ (Zn, Mn)P is obtained in Li $_{1+y}$ (Cd,Mn)P polycrystalline samples by Arrott plot technique. The p-type carriers are determined by Hall effect measurements. The first principle calculations and X-ray diffraction measurements indicate that occupation of excess Li is at Cd sites rather than the interstitial site. Consequently holes are doped by excess Li substitution. More interestingly Li $_{1+y}$ (Cd,Mn)P shows a very low coercive field (100 Oe) and giant negative magnetoresistance (similar to 80%) in ferromagnetic state that will benefit potential spintronics applications.

論文

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

https://doi.org/10.1103/PhysRevB.88.081203

被引用回数：73 パーセンタイル：91.83(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 -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.

論文

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, 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

https://doi.org/10.1038/ncomms2804

被引用回数：97 パーセンタイル：94.65(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.

論文

Elongation of plasma channel for electron acceleration

Chen, L.-M.; 中島一久; Hong, W.*; Hua, J. F.*; 亀島敬; 小瀧秀行; 杉山精博*; Wen, X.*; Wu, Y.*; Tang, C.*; et al.

Chinese Optics Letters, 5(S1), p.S133 - S135, 2007/05

Experiments for the laser guiding studies has been carried out with the 30 fs, 100 TW laser pulse interaction with the long slab and discharged capillary of underdense plasma. Formation of extremely long plasma channel with its length 10 times above the Rayleigh length is observed when the laser pulse power is much higher than the critical power for relativistic self-focusing. The long self-guiding channel formation is accompanied by the quasi-monoenergetic electron acceleration with a low transverse emittance and high electric current (10 nC/shot). In order to continuously elongate plasma channel, a 4 cm-scale discharged capillary was used. We successfully demonstrated laser-plasma acceleration of high-quality electron beams up to nearly GeV. Our results exactly verified the prediction of laser-wakefield acceleration through a cm-scale plasma channel in the blowout bubble regime.

論文

Self-guiding of 100 TW femtosecond laser pulses in centimeter-scale underdense plasma

Chen, L.-M.; 小瀧秀行; 中島一久*; Koga, J. K.; Bulanov, S. V.; 田島俊樹; Gu, Y. Q.*; Peng, H. S.*; Wang, X. X.*; Wen, T. S.*; et al.

Physics of Plasmas, 14(4), p.040703_1 - 040703_4, 2007/04

https://doi.org/10.1063/1.2720374

被引用回数：36 パーセンタイル：75.52(Physics, Fluids & Plasmas)

レーザーの自己導波の調査のため、長いunderdenseのプラズマと100TWレーザーパルスの相互作用実験を行い、レイリー長の約20倍の10mmという非常に長いプラズマチャネルを観測した。レーザーパルスがチャネル中で曲がること、及び電子キャビティ形成が実験的に初めて観測された。

論文

Development of structural analysis program for non-linear elasticity by continuum damage mechanics

加治芳行; Gu, W.*; 石原正博; 荒井長利; 中村均*

Nuclear Engineering and Design, 206(1), p.1 - 12, 2001/05

https://doi.org/10.1016/S0029-5493(01)00335-1

被引用回数：9 パーセンタイル：56.08(Nuclear Science & Technology)

工業用黒鉛材料は、引張荷重に対して非線形な応力-ひずみ挙動を示すが、これは材料内部において分布される微視的空隙とき裂の発生及び進展によって黒鉛材料の剛性が低下することによると考えられている。そこで本論文では、連続体損傷力学を脆性材料構造物の非線形弾性挙動の評価に適用し、構造健全性を損傷パラメータによって評価するプログラムを開発した。また黒鉛構造物を用いた健全性評価試験結果及び弾性解析結果との比較検討した結果、損傷力学を考慮することによってより高精度な損傷評価が可能なことが明らかになった。

報告書

確率論的構造力学解析における並列計算プログラムの基本設計

加治芳行; 荒井長利; Gu, W.*; 中村均*

JAERI-Review 99-016, 61 Pages, 1999/06

JAERI-Review-99-016.pdf:2.37MB

これまでセラミックス製構造物の新たな構造信頼性評価解析法の開発を目的として、潜在欠陥に関する微視的破壊力学をベースとする材料強度理論と連続体構造力学モデルとを融合させる、超並列計算システム対応の計算力学的手法を検討してきた。本論文は、その一環として計算力学プログラムの基本設計のうち主な項目に関係している確率論的構造力学の原理、定式の基礎事項及び並列処理計算のプログラミング手法について調査し、概要をまとめたものである。

論文

Application of continuum damage mechanics for non-linear elastic deformation behaviors of brittle materials

加治芳行; Gu, W.*; 石原正博; 荒井長利; 中村均*

Transactions of 15th Int. Conf. on Structural Mechanics in Reactor Technol. (SMiRT-15), 2, p.133 - 139, 1999/00

工業用黒鉛材料は、引張荷重に対して非線形な応力-ひずみ挙動を示すが、これは材料内部に分布する微視的空隙とき裂の発生及び進展によって黒鉛材料の剛性が低下することによると考えられている。そこで本論文では、連続体損傷力学を脆性材利用構造物の非線形弾性挙動の評価に適用し、構造健全性を損傷パラメータによって評価するプログラムを開発した。また黒鉛構造物を用いた健全性評価試験結果及び弾性解析結果との比較検討の結果、損傷力学を考慮することによってより高精度な損傷評価が可能なことが明らかになった。

口頭

Guiding of 100 TW Relativistic Laser Pulses by 10 mm Plasma Channels

Koga, J. K.; Chen, L.-M.; 小瀧秀行; 中島一久; Bulanov, S. V.; 田島俊樹; Gu, Y. Q.*; Peng, H. S.*; Hua, J. F.*; An, W. M.*; et al.

no journal, ,

100TW, 30fsの相対論的強度のレーザーを長いスリットガスジェット(1.210mm $^{2}$ )へ集光し、レーザー・プラズマ相互作用により電子を発生させる最初の実験を行った。10mmの、レイリー長の20倍となるプラズマチャネルの形成が確認された。このチャネルの特長として、レーザーの偏向,ホース効果,キャビティの形成が確認された。この長いチャネルの形成と同時にコリメートされた(エミッタンス0.8mm mrad),高エネルギーの準単色電子(70MeV)の発生が確認された。このときの1MeV以上の電子の電荷量は 10nC/shotであり、これは長いチャネル形成の効果によるものと考えられる。

口頭

センチメートルスケールのキャピラリー放電プラズマチャネルを用いたレーザー電子加速

亀島敬; 小瀧秀行; 神門正城; 大東出; 川瀬啓悟; 福田祐仁; Chen, L. M.*; 本間隆之; 近藤修司; Esirkepov, T. Z.; et al.

no journal, ,

レーザープラズマ電子加速は非常に高い電場を持っているが、加速空間が非常に短いという問題点を持っているため、その電子ビームの加速エネルギーは100MeV程度に制限されていた。近年、このレーザープラズマ電子加速が抱える問題点をキャピラリー放電管を用いることで大幅に解決がなされた。プラズマは密度が高いほど屈折率が低くなる特徴を利用して放電管の中でプラズマ密度を中心で薄く、その外周を高く分布させれば光ファイバーと同じ原理でレーザーは放電管内のプラズマ中を集光伝搬しながら相互作用する。ゆえに、加速空間を大幅に拡張することができる。この実験を2006年に中国工程物理研究院とKEK、及び原子力機構で共同実験を行い、キャピラリ放電管を用いて4.4Jのレーザーパルスの集光伝搬及び0.56GeVの電子ビームの生成に成功した。加えて、JAEAにて同様の実験を2007年に行い、1Jのレーザーパルスの集光伝搬及び電子ビームの発生に成功した。