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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
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、Co
Zn
Mn
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。
Chen, S.*; Browne, F.*; Doornenbal, P.*; Lee, J.*; Obertelli, A.*; 角田 佑介*; 大塚 孝治*; 茶園 亮樹*; Hagen, G.*; Holt, J. D.*; et al.
Physics Letters B, 843, p.138025_1 - 138025_7, 2023/08
Scからの1陽子ノックアウト反応を用いて、
Caと
Caのガンマ崩壊を観測した。
Caでは1456(12)keVの
線遷移が、
Caでは1115(34)keVの遷移が観測された。どちらの遷移も暫定的に
と割り当てられた。有効核子間相互作用をわずかに修正した広い模型空間での殻模型計算では、
準位エネルギー、2中性子分離エネルギー、反応断面積が実験とよく一致し、N=34閉殻の上に新しい殻が形成されていることを裏付けた。その構成要素である
と
軌道はほぼ縮退しており、これは
Caが二重魔法核である可能性を排除し、Ca同位体のドリップラインを
Caあるいはそれ以上にまで広げる可能性がある。
Chen, Y.*; 浅野 駿*; Wang, T.*; Xie, P.*; 北山 慎之介*; 石井 賢司*; 松村 大樹; 辻 卓也; 谷口 貴紀*; 藤田 全基*
JPS Conference Proceedings (Internet), 38, p.011050_1 - 011050_6, 2023/05
To investigate the variation of the electronic state of -type cuprate due to annealing, we performed Cu
-edge X-ray absorption fine structure measurements on Pr
CuO
(PCO) and Pr
La
CuO
(PLCO). The induced electrons due to annealing (
) in PCO and PLCO were approximately 2
, consistent with a model of electron doping to Mott insulator. Here,
and
represent the amount of excess oxygen from the stoichiometric composition in the as-sintered compound and that of oxygen loss due to annealing, respectively. Furthermore, the energy of the Einstein oscillator (
) for the Cu-O
bond was evaluated by extended X-ray absorption fine structure analysis. (O
denotes the in-plane oxygen.) We found a small annealing effect on
for both PCO and PLCO.
Ren, Q.*; Gupta, M. K.*; Jin, M.*; Ding, J.*; Wu, J.*; Chen, Z.*; Lin, S.*; Fabelo, O.*; Rodriguez-Velamazan, J. A.*; 古府 麻衣子; et al.
Nature Materials, 22, p.999 - 1006, 2023/05
Ultralow thermal conductivity and fast ionic diffusion endow superionic materials with excellent performance both as thermoelectric converters and as solid-state electrolytes. Yet the correlation and interdependence between these two features remain unclear owing to a limited understanding of their complex atomic dynamics. Here we investigate ionic diffusion and lattice dynamics in argyrodite AgSnSe
using synchrotron X-ray and neutron scattering techniques along with machine-learned molecular dynamics. We identify a critical interplay of the vibrational dynamics of mobile Ag and a host framework that controls the overdamping of low-energy Ag-dominated phonons into a quasi-elastic response, enabling superionicity. Concomitantly, the persistence of long-wavelength transverse acoustic phonons across the superionic transition challenges a proposed 'liquid-like thermal conduction' picture. Rather, a striking thermal broadening of low-energy phonons, starting even below 50 K, reveals extreme phonon anharmonicity and weak bonding as underlying features of the potential energy surface responsible for the ultralow thermal conductivity (
0.5 Wm
K
) and fast diffusion. Our results provide fundamental insights into the complex atomic dynamics in superionic materials for energy conversion and storage.
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:1 パーセンタイル:72.98(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 and ferromagnetic La
Sr
MnO
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.
Guo, B.*; Mao, W.; Chong, Y.*; 柴田 曉伸*; Harjo, S.; Gong, W.; Chen, H.*; Jonas, J. J.*; 辻 伸泰*
Acta Materialia, 242, p.118427_1 - 118427_11, 2023/01
被引用回数:2 パーセンタイル:46.51(Materials Science, Multidisciplinary)Dynamic transformation from alpha (HCP) to beta (BCC) phase in a zirconium alloy was revealed by the use of in-situ neutron diffraction during hot compression. The dynamic transformation was unexpectedly detected during isothermal compression at temperatures of 900C and 950
C (alpha + beta two-phase region) and strain rates of 0.01 s
and 0.001 s
, even though equilibrium two-phase states were achieved prior to the hot compression. Dynamic transformation was accompanied by diffusion of Sn from beta to alpha phase, which resulted in changes of lattice parameters and a characteristic microstructure of alpha grains. The details of dynamic transformation are discussed using the evolution of lattice constants.
飯村 俊*; Rosenbusch, M.*; 高峰 愛子*; 角田 佑介*; 和田 道治*; Chen, S.*; Hou, D. S.*; Xian, W.*; 石山 博恒*; Yan, S.*; et al.
Physical Review Letters, 130(1), p.012501_1 - 012501_6, 2023/01
被引用回数:1 パーセンタイル:77.02(Physics, Multidisciplinary)The atomic masses of Sc,
Ti, and
V have been determined using the high-precision multireflection time-of-flight technique. The radioisotopes have been produced at RIKEN's Radioactive Isotope Beam Factory (RIBF) and delivered to the novel designed gas cell and multireflection system, which has been recently commissioned downstream of the ZeroDegree spectrometer following the BigRIPS separator. For
Ti and
V, the mass uncertainties have been reduced down to the order of 10 keV, shedding new light on the
shell effect in Ti and V isotopes by the first high-precision mass measurements of the critical species
Ti and
V. With the new precision achieved, we reveal the nonexistence of the
empirical two-neutron shell gaps for Ti and V, and the enhanced energy gap above the occupied
p
orbit is identified as a feature unique to Ca. We perform new Monte Carlo shell model calculations including the
d
and
g
orbits and compare the results with conventional shell model calculations, which exclude the
g
and the
d
orbits. The comparison indicates that the shell gap reduction in Ti is related to a partial occupation of the higher orbitals for the outer two valence neutrons at
.
Elekes, Z.*; Juhsz, M. M.*; Sohler, D.*; Sieja, K.*; 吉田 数貴; 緒方 一介*; Doornenbal, P.*; Obertelli, A.*; Achouri, N. L.*; 馬場 秀忠*; et al.
Physical Review C, 106(6), p.064321_1 - 064321_10, 2022/12
被引用回数:0 パーセンタイル:0.02(Physics, Nuclear)Vと
Vの低励起準位構造を初めて探索した。
Vについては中性子ノックアウト反応と陽子非弾性散乱が、
Vについては中性子ノックアウト反応データが得られた。
Vについては4つ、
Vについては5つの新たな遷移が確認された。Lenzi-Nowacki-Poves-Sieja (LNPS)相互作用に基づく殻模型計算との比較によって、それぞれの同位体について確認されたガンマ線のうち3つが、first 11/2
状態とfirst 9/2
状態からの崩壊と決定された。
Vについては、(
,
)非弾性散乱断面積は四重極変形と十六重極変形を想定したチャネル結合法により解析されたが、十六重極変形の影響により、明確に反転の島に属するとは決定できなかった。
Enciu, M.*; Liu, H. N.*; Obertelli, A.*; Doornenbal, P.*; Nowacki, F.*; 緒方 一介*; Poves, A.*; 吉田 数貴; Achouri, N. L.*; 馬場 秀忠*; et al.
Physical Review Letters, 129(26), p.262501_1 - 262501_7, 2022/12
被引用回数:0 パーセンタイル:37.16(Physics, Multidisciplinary)230MeV/nucleonでの
Caからの中性子ノックアウト反応が
線分光と行われ、
と
軌道からの中性子ノックアウト反応の運動量分布が測定された。断面積は
の閉殻と整合し、Ca同位体での
と
閉殻と同程度に強い閉殻であることが確認された。運動量分布の分析から
と
軌道の平均二乗根半径の差は0.61(23)fmと決定され、これはmodified-shell-modelによる予言の0.7fmと整合した。これは、中性子過剰なCa同位体での
軌道半径が大きいことが、中性子数にしたがって線形的に荷電半径が増える意外な現象の原因であることを示唆している。
Khalil, A. M. E.*; Han, L.*; Maamoun, I.; Tabish, T. A.*; Chen, Y.*; Eljamal, O.*; Zhang, S.*; Butler, D.*; Memon, F. A.*
Advanced Sustainable Systems (Internet), 6(8), p.2200016_1 - 2200016_16, 2022/08
被引用回数:0 パーセンタイル:0(Green & Sustainable Science & Technology)Graphene-based materials have emerged as alternative adsorbents, but their success in removing pharmaceutical contaminants has been limited due to degradation caused by restacking and limited control over their sizes and porosities. Driven by this issue, in the current study, to counteract the restacking behavior, graphene sheets are supported on a thread/rod-like matrix structure in a boron nitride foam material, and a novel porous composite foam-supported graphene is synthesized. The as-prepared novel composite offers extraordinary features, such as high absorption kinetics, large available surface area, high porosity, ecofriendliness and cost-effective synthesis, and excellent affinity to emerging pharmaceutical contaminants. When batch-testing graphene-based foam material and porous graphene nanosheets to remove gemfibrozil (GEM) from wastewater samples, rapid adsorption kinetics (less than 5 min) are exhibited by the graphene-based foam. Column filter studies are conducted for both materials to test their performance in removing GEM from distilled water, synthetic graywater, and actual wastewater. Overall, the foam composite-based filter marginally outperforms the sand-supported graphene filter and significantly outperforms the unsupported graphene filter. A numerical MATLAB model is developed to simulate the reactive solute transport of GEM influent through the foam filter. Also, a formal sensitivity analysis is conducted to identify the key parameters influencing the model results.
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
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 BaK
(Zn
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
Mn
As, it is concluded that the ground state of Mn in Ba
K
(Zn
Mn
)
As
consists of both the
and
electron configurations.
小岩井 拓真*; Wimmer, K.*; Doornenbal, P.*; Obertelli, A.*; Barbieri, C.*; Duguet, T.*; Holt, J. D.*; 宮城 宇志*; Navrtil, P.*; 緒方 一介*; et al.
Physics Letters B, 827, p.136953_1 - 136953_7, 2022/04
被引用回数:2 パーセンタイル:63.62(Astronomy & Astrophysics)中性子過剰核Caでは、新魔法数34が発見されて以来、その構造を知るために多くの実験がなされてきたが、それを超える中性子過剰核の情報は全く知られてこなかった。本論文では、理化学研究所RIBFにて
K,
Ca,
Caの励起状態から脱励起するガンマ線を初めて観測した結果を報告した。それぞれ1つのガンマ線しか得られなかったものの、
Kおよび
Caのデータは、それぞれ、陽子の
と
軌道間のエネルギー差、中性子の
と
軌道間のエネルギー差を敏感に反映し、両方とも最新の殻模型計算によって200keV程度の精度で再現できることがわかった。また、1粒子状態の程度を特徴づける分光学的因子を実験データと歪曲波インパルス近似による反応計算から求め、その値も殻模型計算の値と矛盾しないことがわかった。
青柳 和平; 石井 英一; Chen, Y.*; 石田 毅*
Rock Mechanics and Rock Engineering, 55(4), p.1855 - 1869, 2022/04
被引用回数:3 パーセンタイル:64.29(Engineering, Geological)高レベル放射性廃棄物の安全評価では廃棄体から地下水に漏洩した放射性核種の長期的な移動を評価するために、処分場の坑道掘削により坑道周辺に形成される掘削損傷領域割れ目の長期定な透水性を推定する必要がある。本研究は幌延深地層研究センターの地下坑道において、掘削損傷領域割れ目のせん断誘発膨張が同割れ目の開口幅に与える影響を定量的に調べるために、同割れ目を予め樹脂注入より固化した状態で掘削・採取し、観察した。これまで、掘削損傷領域割れ目のせん断変位を詳細に計測した事例はなかったが、せん断誘発膨張が割れ目開口に与える影響を理解することは、坑道埋め戻し後の割れ目の長期的な透水性を評価する上で重要である。樹脂により固化された割れ目の拡大写真を用いて、割れ目のラフネス、せん断変位、および開口幅を詳細に計測した結果、せん断変位量と開口幅に相関性は認められず、割れ目形成後のせん断膨張は有意に生じていないことが示された。この結果は既存の経験則を用いたシミュレーションでも再現でき、深度350mのやや高い垂直応力がせん断誘発膨張を抑制していることが考えられた。垂直応力が大きく低下しない限りは、仮に割れ目がせん断しても、割れ目の開口幅が有意に増加する可能性は低いと考えられる。坑道埋め戻し後の掘削損傷領域割れ目のせん断膨張の可能性を検討する上で、原位置における樹脂注入試験と詳細な割れ目観察は有効な手法であることを示した。
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:10 パーセンタイル:75.68(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(BFO)/La
Sr
MnO
(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
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.
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
被引用回数:1 パーセンタイル:10.8(Astronomy & Astrophysics)The long-lived 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
Fe(n,
)
Fe on
Fe (half-life=44.5 days) is the key reaction for the production of
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
Fe(n,
)
Fe cross sections in which all the components are included. We derived a Maxwellian-averaged cross section of 27.5
3.5 mb at
= 30 keV and 13.4
1.7 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
Fe from the
Fe(n,
)
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
Fe.
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:8 パーセンタイル:68.73(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/GdGa
O
(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.
Linh, B. D.*; Corsi, A.*; Gillibert, A.*; Obertelli, A.*; Doornenbal, P.*; Barbieri, C.*; Chen, S.*; Chung, L. X.*; Duguet, T.*; Gmez-Ramos, M.*; et al.
Physical Review C, 104(4), p.044331_1 - 044331_16, 2021/10
被引用回数:3 パーセンタイル:53.21(Physics, Nuclear)理化学研究所のRIビームファクトリーにて中性子過剰Clの励起状態を
Arからのノックアウト反応によって生成し、脱励起ガンマ線からそのエネルギー準位を測定した。また、陽子ノックアウトの運動量分布から
Clの基底状態が
であることがわかった。その結果を大規模殻模型計算およびいくつかの第一原理計算と比較した。
Cl同位体の基底状態および第一励起状態は、計算で用いた相互作用に敏感であることがわかった。それは、陽子の一粒子エネルギーと四重極集団運動との複雑な結合によるためであると考えられる。
Qi, J.*; Hou, D.*; Chen, Y.*; 齊藤 英治; Jin, X.*
Journal of Magnetism and Magnetic Materials, 534, p.167980_1 - 167980_6, 2021/09
被引用回数:1 パーセンタイル:10.14(Materials Science, Multidisciplinary)Temperature dependence of the spin Hall magnetoresistance (SMR) has been investigated herein Pt/CrO
/Y
Fe
O
structure. Well below the N
el temperature of Cr
O
, the SMR is not observed at the noise level of 1.2 ppm. In vicinity of the N
el temperature, only a positive SMR tracks the YIG magnetic switching process, supporting that the SMR of normal metal/antiferromagnetic insulator/ferromagnetic insulator trilayer is controlled by the N
el vector of the antiferromagnetic insulator. A high field magnetoresistance is observed up to an external magnetic field of 20000 Oe which has a field angle dependence symmetry consistent with the SMR. We attribute this high field magnetoresistance to be induced by the Hanle magnetoresistance in Pt.
Chen, Y.*; 佐藤 正寛*; Tang, Y.*; 塩見 雄毅*; 大柳 洸一*; 益田 隆嗣*; 南部 雄亮*; 藤田 全基*; 齊藤 英治
Nature Communications (Internet), 12, p.5199_1 - 5199_7, 2021/08
被引用回数:5 パーセンタイル:57.41(Multidisciplinary Sciences)A triplon refers to a fictitious particle that carries angular momentum corresponding to the elementary excitation in a broad class of quantum dimerized spin systems. Such systems without magnetic order have long been studied as a testing ground for quantum properties of spins. Although triplons have been found to play a central role in thermal and magnetic properties in dimerized magnets with singlet correlation, a spin angular momentum flow carried by triplons, a triplon current, has not been detected yet. Here we report spin Seebeck effects induced by a triplon current: triplon spin Seebeck effect, using a spin-Peierls system CuGeO
. The result shows that the heating-driven triplon transport induces spin current whose sign is positive, opposite to the spin-wave cases in magnets. The triplon spin Seebeck effect persists far below the spin-Peierls transition temperature, being consistent with a theoretical calculation for triplon spin Seebeck effects.
Browne, F.*; Chen, S.*; Doornenbal, P.*; Obertelli, A.*; 緒方 一介*; 宇都野 穣; 吉田 数貴; Achouri, N. L.*; 馬場 秀忠*; Calvet, D.*; et al.
Physical Review Letters, 126(25), p.252501_1 - 252501_7, 2021/06
被引用回数:8 パーセンタイル:74.27(Physics, Multidisciplinary)理化学研究所RIビームファクトリーにて、中性子過剰核Scからの1陽子ノックアウト反応によって
Caを生成し、そのエネルギー準位と反応断面積をガンマ線分光および不変質量分光によって得た。その結果を歪曲波インパルス近似による核反応計算と大規模殻模型による核構造計算を組み合わせた理論値と比較した。実験の準位と断面積は理論計算によってよく再現された。
Caの正パリティ状態については、基底状態の生成断面積が励起状態のものに比べて圧倒的に大きいという結果が得られた。これは、
Scでは中性子魔法数34が消滅し
Caではその魔法数が存在するというこれまでの知見と一見矛盾するが、対相関による分光学的因子のコヒーレンスから理解することができる。