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Study of the $$N=32$$ and $$N=34$$ shell gap for Ti and V by the first high-precision multireflection time-of-flight mass measurements at BigRIPS-SLOWRI

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

The atomic masses of $$^{55}$$Sc, $$^{56,58}$$Ti, and $$^{56-59}$$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 $$^{56,58}$$Ti and $$^{56-59}$$V, the mass uncertainties have been reduced down to the order of 10 keV, shedding new light on the $$N=34$$ shell effect in Ti and V isotopes by the first high-precision mass measurements of the critical species $$^{58}$$Ti and $$^{59}$$V. With the new precision achieved, we reveal the nonexistence of the $$N=34$$ empirical two-neutron shell gaps for Ti and V, and the enhanced energy gap above the occupied $$nu$$p$$_{3/2}$$ orbit is identified as a feature unique to Ca. We perform new Monte Carlo shell model calculations including the $$nu$$d$$_{5/2}$$ and $$nu$$g$$_{9/2}$$ orbits and compare the results with conventional shell model calculations, which exclude the $$nu$$g$$_{9/2}$$ and the $$nu$$d$$_{5/2}$$ 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 $$N = 34$$.


Spin Hall magnetoresistance in Pt/Cr$$_2$$O$$_3$$/YIG structure

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:16.71(Materials Science, Multidisciplinary)

Temperature dependence of the spin Hall magnetoresistance (SMR) has been investigated herein Pt/Cr$$_2$$O$$_3$$/Y$$_3$$Fe$$_5$$O$$_{12}$$ structure. Well below the N$'{e}$el temperature of Cr$$_2$$O$$_3$$, the SMR is not observed at the noise level of 1.2 ppm. In vicinity of the N$'{e}$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$'{e}$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.


Quasifree neutron knockout reaction reveals a small $$s$$-Orbital component in the Borromean nucleus $$^{17}$$B

Yang, Z. H.*; 久保田 悠樹*; Corsi, A.*; 吉田 数貴; Sun, X.-X.*; Li, J. G.*; 木村 真明*; Michel, N.*; 緒方 一介*; Yuan, C. X.*; et al.

Physical Review Letters, 126(8), p.082501_1 - 082501_8, 2021/02


 被引用回数:25 パーセンタイル:96.89(Physics, Multidisciplinary)

ボロミアン核であり中性子ハロー構造が期待される$$^{17}$$Bに対する($$p$$,$$pn$$)反応実験を行った。断面積の運動量分布を分析することで、$$1s_{1/2}$$$$0d_{5/2}$$軌道の分光学的因子を決定した。驚くべきことに、$$1s_{1/2}$$の分光学的因子は9(2)%と小さいことが明らかになった。この結果は、連続状態を含むdeformed relativistic Hartree-Bogoliubov理論によってよく説明された。本研究の結果によると、現在知られているハロー構造を持つとされる原子核の中で$$^{17}$$Bは$$s$$および$$p$$軌道の成分が最も小さく、$$s$$または$$p$$軌道成分が支配的であることが必ずしもハロー構造の前提条件ではない可能性を示唆している。


The Joint evaluated fission and fusion nuclear data library, JEFF-3.3

Plompen, A. J. M.*; Cabellos, O.*; De Saint Jean, C.*; Fleming, M.*; Algora, A.*; Angelone, M.*; Archier, P.*; Bauge, E.*; Bersillon, O.*; Blokhin, A.*; et al.

European Physical Journal A, 56(7), p.181_1 - 181_108, 2020/07

 被引用回数:180 パーセンタイル:99.41(Physics, Nuclear)

本論文では、核分裂と核融合のための統合評価済み核データファイルのバージョン3.3(JEFF-3.3)について説明する。中性子との反応が重要な核種の$$^{235}$$U, $$^{238}$$U, $$^{239}$$Pu, $$^{241}$$Am, $$^{23}$$Na, $$^{59}$$Ni, Cr, Cu, Zr, Cd, Hf, Au, Pb, Biについて、新しい核データ評価結果を示す。JEFF-3.3には、核分裂収率, 即発核分裂スペクトル, 核分裂平均中性子発生数の新しいデータが含まれる。更に、放射崩壊, 熱中性子散乱, ガンマ線放出, 中性子による放射化, 遅発中性子, 照射損傷に関する新しいデータも含まれている。JEFF-3.3は、TENDLプロジェクトのファイルで補完しており、光子, 陽子, 重陽子, 三重陽子, $$^{3}$$He核, アルファ粒子による反応ライブラリについては、TENDL-2017から採用した。また、不確かさの定量化に対する要求の高まりから、多くの共分散データが新しく追加された。JEFF-3.3を用いた解析の結果と臨界性, 遅発中性子割合, 遮蔽, 崩壊熱に対するベンチマーク実験の結果を比較することにより、JEFF-3.3は幅広い原子核技術の応用分野、特に原子力エネルギーの分野において優れた性能を持っていることが分かった。


Crystalline dependence of spin transmission in Cr$$_2$$O$$_3$$ thin films

Qin, J.*; Hou, D.*; Chen, Y.*; 齊藤 英治; Jin, X.*

Journal of Magnetism and Magnetic Materials, 501, p.166362_1 - 166362_4, 2020/05

 被引用回数:3 パーセンタイル:27.83(Materials Science, Multidisciplinary)

Spin transmission in Cr$$_2$$O$$_3$$ films of different crystalline textures is studied experimentally. With Y$$_3$$Fe$$_5$$O$$_{12}$$/Cr$$_2$$O$$_3$$/Pt trilayer devices, a spin current is injected into Cr$$_2$$O$$_3$$ by spin pumping from Y$$_3$$Fe$$_5$$O$$_{12}$$, and the spin transmission is monitored by the inverse spin Hall voltage ($$V_mathrm{ISHE}$$) in Pt. For (0001) plane textured Cr$$_2$$O$$_3$$ films, $$V_mathrm{ISHE}$$ vanishes quickly below the N$'{e}$el temperature. However, the $$V_mathrm{ISHE}$$ shows a broad shoulder below the N$'{e}$el temperature for $$(11bar{2}0)$$ and $$(11bar{2}3)$$ plane co-textured Cr$$_2$$O$$_3$$. Such a difference in the temperature dependence of Cr$$_2$$O$$_3$$ can be understood by the different N$'{e}$el vector orientations with respect to the injected spin moment direction.


Clades of huge phages from across Earth's ecosystems

Al-Shayeb, B.*; Sachdeva, R.*; Chen, L.-X.*; Ward, F.*; Munk, P.*; Devoto, A.*; Castelle, C. J.*; Olm, M. R.*; Bouma-Gregson, K.*; 天野 由記; et al.

Nature, 578(7795), p.425 - 431, 2020/02

 被引用回数:161 パーセンタイル:99.55(Multidisciplinary Sciences)

Phage typically have small genomes and depend on their bacterial hosts for replication. We generated metagenomic datasets from many diverse ecosystems and reconstructed hundreds of huge phage genomes, between 200 kbp and 716 kbp in length. Thirty four genomes were manually curated to completion, including the largest phage genomes yet reported. Expanded genetic repertoires include diverse and new CRISPR-Cas systems, tRNAs, tRNA synthetases, tRNA modification enzymes, initiation and elongation factors and ribosomal proteins. Phage CRISPR have the capacity to silence host transcription factors and translational genes, potentially as part of a larger interaction network that intercepts translation to redirect biosynthesis to phage-encoded functions. Some phage repurpose bacterial systems for phage-defense to eliminate competing phage. We phylogenetically define seven major clades of huge phage from human and other animal microbiomes, oceans, lakes, sediments, soils and the built environment. We conclude that large gene inventories reflect a conserved biological strategy, observed across a broad bacterial host range and resulting in the distribution of huge phage across Earth's ecosystems.


Fine structure in the $$alpha$$ decay of $$^{223}$$U

Sun, M. D.*; Liu, Z.*; Huang, T. H.*; Zhang, W. Q.*; Andreyev, A. N.; Ding, B.*; Wang, J. G.*; Liu, X. Y.*; Lu, H. Y.*; Hou, D. S.*; et al.

Physics Letters B, 800, p.135096_1 - 135096_5, 2020/01

 被引用回数:9 パーセンタイル:83.19(Astronomy & Astrophysics)

Fine structure in the $$alpha$$ decay of $$^{223}$$U was observed in the fusion-evaporation reaction $$^{187}$$Re($$^{40}$$Ar,p3n) by using fast digital pulse processing technique. Two $$alpha$$-decay branches of $$^{223}$$U feeding the ground state and 244 keV excited state of $$^{219}$$Th were identified by establishing the decay chain $$^{223}$$U$$rightarrow$$$$^{219}$$Th$$rightarrow$$$$^{215}$$Ra$$rightarrow$$$$^{211}$$Rn. The $$alpha$$-particle energy for the ground-state to ground-state transition of $$^{223}$$U was determined to be 8993(17) keV, 213 keV higher than the previous value, the half-life was updated to be 62$$^{+14}_{-10} mu$$s. Evolution of nuclear structure for $$N$$=131 even-$$Z$$ isotones from Po to U was discussed in the frameworks of nuclear mass and reduced $$alpha$$-decay width, a weakening octupole deformation in the ground state of $$^{223}$$U relative to its lighter isotones $$^{219}$$Ra and $$^{211}$$Th was suggested.


Spin transport in antiferromagnetic insulators; Progress and challenges

Hou, D.*; Qiu, Z.*; 齊藤 英治

NPG Asia Materials, 11, p.35_1 - 35_6, 2019/07

 被引用回数:34 パーセンタイル:87.07(Materials Science, Multidisciplinary)

Spin transport is a key process in the operation of spin-based devices that has been the focus of spintronics research for the last two decades. Conductive materials, such as semiconductors and metals, in which the spin transport relies on electron diffusion, have been employed as the channels for spin transport in most studies. Due to the absence of conduction electrons, the potential to be a spin channel has long been neglected for insulators. However, since the demonstration of spin transmission through a ferromagnetic insulator, it was realized that insulators with magnetic ordering can also serve as channels for spin transport. Here, the recent progress of spin transport in antiferromagnetic insulators is briefly described with an introduction to the experimental techniques. The observations regarding the temperature dependence of spin transmission, spin current switching and the negative spin Hall magnetoresistance are discussed. We also include the challenges for developing the functionality of antiferromagnetic insulators as well as the unresolved problems from the experimental observations.


Spin colossal magnetoresistance in an antiferromagnetic insulator

Qiu, Z.*; Hou, D.*; Barker, J.*; 山本 慧; Gomonay, O.*; 齊藤 英治*

Nature Materials, 17(7), p.577 - 580, 2018/05

 被引用回数:91 パーセンタイル:96.5(Chemistry, Physical)



Scaling of memories and crossover in glassy magnets

Samarakoon, A. M.*; 高橋 満*; Zhang, D.*; Yang, J.*; 片山 尚幸*; Sinclair, R.*; Zhou, H. D.*; Diallo, S. O.*; Ehlers, G.*; Tennant, D. A.*; et al.

Scientific Reports (Internet), 7(1), p.12053_1 - 12053_8, 2017/09


 被引用回数:5 パーセンタイル:44.55(Multidisciplinary Sciences)

Glassiness is ubiquitous and diverse in characteristics in nature. Understanding their differences and classification remains a major scientific challenge. Here, we show that scaling of magnetic memories with time can be used to classify magnetic glassy materials into two distinct classes. The systems studied are high temperature superconductor-related materials, spin-orbit Mott insulators, frustrated magnets, and dilute magnetic alloys. Our bulk magnetization measurements reveal that most densely populated magnets exhibit similar memory behavior characterized by a relaxation exponent of $$1-n$$ $$approx$$ $$0.6$$(1). This exponent is different from $$1-n$$ $$approx$$ $$1/3$$ of dilute magnetic alloys that was ascribed to their hierarchical and fractal energy landscape, and is also different from $$1-n=1$$ of the conventional Debye relaxation expected for a spin solid, a state with long range order.


Antiferromagnetic anisotropy determination by spin Hall magnetoresistance

Wang, H.*; Hou, D.*; Qiu, Z.*; 吉川 貴史*; 齊藤 英治; Jin, X.*

Journal of Applied Physics, 122(8), p.083907_1 - 083907_6, 2017/08

 被引用回数:2 パーセンタイル:11.23(Physics, Applied)

An electric method for measuring magnetic anisotropy in antiferromagnetic insulators (AFIs) is proposed. When a metallic film with strong spin-orbit interactions, e.g., platinum (Pt), is deposited on an AFI, its resistance should be affected by the direction of the AFI N$'e$el vector due to the spin Hall magnetoresistance (SMR). Accordingly, the direction of the AFI N$'e$el vector, which is affected by both the external magnetic field and the magnetic anisotropy, is reflected in resistance of Pt. The magnetic field angle dependence of the resistance of Pt on AFI is calculated by considering the SMR, which indicates that the antiferromagnetic anisotropy can be obtained experimentally by monitoring the Pt resistance in strong magnetic fields. Calculations are performed for realistic systems such as Pt/Cr$$_2$$O$$_3$$, Pt/NiO, and Pt/CoO.


Time-resolved study of field-induced suppression of longitudinal spin Seebeck effect

日置 友智*; 井口 亮*; Qiu, Z.*; Hou, D.*; 内田 健一*; 齊藤 英治

Applied Physics Express, 10(7), p.073002_1 - 073002_4, 2017/06

 被引用回数:12 パーセンタイル:52.6(Physics, Applied)

We have investigated the magnetic-field-induced suppression of the longitudinal spin Seebeck effect (LSSE) by using a time-resolved measurement technique at room temperature. The result manifested two distinctive time domains: the short-time domain where the observed voltage is insensitive to the magnetic fields, and the long-time domain where the both response time and the magnitude of the observed voltage decreased simultaneously by the magnetic fields. We estimated the magnon propagation length by fitting the transient LSSE response. The propagation length shows a strong dependence on the applied magnetic field, indicating the importance of long-range and low-frequency magnons in the LSSE.


Tunable sign change of spin hall magnetoresistance in Pt/NiO/YIG structures

Hou, D.*; Qiu, Z.*; Barker, J.*; 佐藤 浩司*; 山本 慧; V$'e$lez, S.*; Gomez-Perez, J. M.*; Hueso, L. E.*; Casanova, F.*; 齊藤 英治

Physical Review Letters, 118(14), p.147202_1 - 147202_6, 2017/04

 被引用回数:102 パーセンタイル:97.62(Physics, Multidisciplinary)

Spin Hall magnetoresistance (SMR) has been investigated in Pt/NiO/YIG structures in a wide range of temperature and NiO thickness. The SMR shows a negative sign below a temperature that increases with the NiO thickness. This is contrary to a conventional SMR theory picture applied to the Pt/YIG bilayer, which always predicts a positive SMR. The negative SMR is found to persist even when NiO blocks the spin transmission between Pt and YIG, indicating it is governed by the spin current response of the NiO layer. We explain the negative SMR by the NiO "spin flop" coupled with YIG, which can be overridden at higher temperature by positive SMR contribution from YIG. This highlights the role of magnetic structure in antiferromagnets for transport of pure spin current in multilayers.


Spin-current probe for phase transition in an insulator

Qiu, Z.*; Li, J.*; Hou, D.*; Arenholz, E.*; N'Diaye, A. T.*; Tan, A.*; 内田 健一*; 佐藤 浩司*; 岡本 聡*; Tserkovnyak, Y.*; et al.

Nature Communications (Internet), 7, p.12670_1 - 12670_6, 2016/08

 被引用回数:129 パーセンタイル:97.29(Multidisciplinary Sciences)

Spin fluctuation and transition have always been one of the central topics of magnetism and condensed matter science. Experimentally, the spin fluctuation is found transcribed onto scattering intensity in the neutron-scattering process, which is represented by dynamical magnetic susceptibility and maximized at phase transitions. Importantly, a neutron carries spin without electric charge, and therefore it can bring spin into a sample without being disturbed by electric energy. However, large facilities such as a nuclear reactor are necessary. Here we show that spin pumping, frequently used in nanoscale spintronic devices, provides a desktop microprobe for spin transition; spin current is a flux of spin without an electric charge and its transport reflects spin excitation. We demonstrate detection of antiferromagnetic transition in ultra-thin CoO films via frequency-dependent spin-current transmission measurements, which provides a versatile probe for phase transition in an electric manner in minute devices.


Observation of temperature-gradient-induced magnetization

Hou, D.*; Qiu, Z.*; 井口 亮*; 佐藤 浩司*; Vehstedt, E. K.*; 内田 健一*; Bauer, G. E. W.*; 齊藤 英治

Nature Communications (Internet), 7, p.12265_1 - 12265_6, 2016/07

 被引用回数:12 パーセンタイル:65.4(Multidisciplinary Sciences)

Applying magnetic fields has been the method of choice to magnetize non-magnetic materials, but they are difficult to focus. The magneto-electric effect and voltage-induced magnetization generate magnetization by applied electric fields, but only in special compounds or heterostructures. Here we demonstrate that a simple metal such as gold can be magnetized by a temperature gradient or magnetic resonance when in contact with a magnetic insulator by observing an anomalous Hall-like effect, which directly proves the breakdown of time-reversal symmetry. Such Hall measurements give experimental access to the spectral spin Hall conductance of the host metal, which is closely related to other spin caloritronics phenomena such as the spin Nernst effect and serves as a reference for theoretical calculation.


All-oxide spin Seebeck effects

Qiu, Z.*; Hou, D.*; 吉川 貴史*; 内田 健一*; 齊藤 英治

Applied Physics Express, 8(8), p.083001_1 - 083001_3, 2015/08

 被引用回数:27 パーセンタイル:74.28(Physics, Applied)

We report the observation of longitudinal spin Seebeck effects (LSSEs) in an all-oxide bilayer system comprising an IrO$$_2$$ film and an Y$$_3$$Fe$$_5$$O$$_{12}$$ film. Spin currents, which are generated by a temperature gradient across the IrO$$_2$$/Y$$_3$$Fe$$_5$$O$$_{12}$$ interface, were detected as a voltage via the inverse spin Hall effect in the conductive IrO$$_{2}$$ layer. This voltage is proportional to the magnitude of the temperature gradient; its magnetic field dependence is consistent with the characteristics of LSSEs. This demonstration may lead to the realization of low-cost, stable, transparent spin-current-driven thermoelectric devices.


Intrinsic surface magnetic anisotropy in Y$$_{3}$$Fe$$_{5}$$O$$_{12}$$ as the origin of low-magnetic-field behavior of the spin Seebeck effect

内田 健一*; 大江 純一郎*; 吉川 貴史*; 大門 俊介*; Hou, D.*; Qiu, Z.*; 齊藤 英治

Physical Review B, 92(1), p.014415_1 - 014415_8, 2015/07

 被引用回数:30 パーセンタイル:77.11(Materials Science, Multidisciplinary)

The magnetic-field dependence of the longitudinal spin Seebeck effect (LSSE) in a Pt/Y$$_{3}$$Fe$$_{5}$$O$$_{12}$$ (YIG)-slab junction system was found to deviate from a bulk magnetization curve of the YIG slab in a low field range. In this paper, we show that the deviation originates from the difference between surface and bulk magnetization processes in the YIG slab and that it appears even when removing possible extrinsic magnetic anisotropy due to surface roughness and replacing the Pt layer with different materials. This result indicates that the anomalous field dependence of the LSSE is due to an intrinsic magnetic property of the YIG surface. Our numerical calculation based on the Landau-Lifshitz-Gilbert equation shows that the deviation between the LSSE and bulk magnetization curves is qualitatively explained by introducing easy-axis perpendicular magnetic anisotropy near the surface of YIG.


Spin-current injection and detection in $$kappa$$-(BEDT-TTF)$$_{2}$$Cu[N(CN)$$_{2}$$]Br

Qiu, Z.*; 賣市 幹大*; Hou, D.*; 内田 健一*; 山本 浩史*; 齊藤 英治

AIP Advances (Internet), 5(5), p.057167_1 - 057167_7, 2015/05

 被引用回数:15 パーセンタイル:57.47(Nanoscience & Nanotechnology)

Spin-current injection into an organic semiconductor $$kappa$$-(BEDT-TTF)$$_{2}$$Cu[N(CN)$$_{2}$$]Br film induced by the spin pumping from an yttrium iron garnet (YIG) film. When magnetization dynamics in the YIG film is excited by ferromagnetic or spin-wave resonance, a voltage signal was found to appear in the $$kappa$$-(BEDT-TTF)$$_{2}$$Cu[N(CN)$$_{2}$$]Br film. Magnetic-field-angle dependence measurements indicate that the voltage signal is governed by the inverse spin Hall effect in $$kappa$$-(BEDT-TTF)$$_{2}$$Cu[N(CN)$$_{2}$$]Br. We found that the voltage signal in the $$kappa$$-(BEDT-TTF)$$_{2}$$Cu[N(CN)$$_{2}$$]Br/YIG system is critically suppressed around 80 K, around which magnetic and/or glass transitions occur, implying that the efficiency of the spin-current injection is suppressed by fluctuations which critically enhanced near the transitions.


Influence of interface condition on spin-Seebeck effects

Qiu, Z.*; Hou, D.*; 内田 健一*; 齊藤 英治

Journal of Physics D; Applied Physics, 48(16), p.164013_1 - 164013_5, 2015/04

 被引用回数:38 パーセンタイル:83.11(Physics, Applied)

The longitudinal spin-Seebeck effect (LSSE) has been investigated for Pt/yttrium iron garnet (YIG) bilayer systems. The magnitude of the voltage induced by the LSSE is found to be sensitive to the Pt/YIG interface condition. We observed large LSSE voltage in a Pt/YIG system with a better crystalline interface, while the voltage decays steeply when an amorphous layer is introduced at the interface artificially.


Active sites and mechanisms for oxygen reduction reaction on nitrogen-doped carbon alloy catalysts; Stone-Wales defect and curvature effect

Chai, G.-L.*; Hou, Z.*; Shu, D.-J.*; 池田 隆司; 寺倉 清之*

Journal of the American Chemical Society, 136(39), p.13629 - 13640, 2014/10

 被引用回数:228 パーセンタイル:97.68(Chemistry, Multidisciplinary)


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