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

https://doi.org/10.1103/PhysRevB.104.134428

We report the observation of the spin Hall magnetoresistance (SMR) in a paramagnetic insulator. By measuring the transverse resistance in a Pt/GdGaO (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.

Evaluation of edge domains in giant magnetoresistive junctions

Frost, W.*; 関 剛斎*; 窪田 崇秀*; Ramos, R.*; 齊藤 英治; 高梨 弘毅*; 廣畑 貴文*

Applied Physics Letters, 118(17), p.172405_1 - 172405_5, 2021/04

https://doi.org/10.1063/5.0049315

We demonstrate that the spin-Seebeck effect can be used to estimate the volume of edge domains formed in a giant magnetoresistive (GMR) device. The thermal gradient induced by Joule heating can be harnessed by the addition of a ferromagnetically insulating channel of FeO on the sides of the GMR pillar. This generates a spin wave in FeO, which couples with the free-layer edge magnetization and controls the reversal of the ferromagnetic layers in one direction only, increasing the current density from A/cm to A/cm. By simple assumption, we estimate the effect of the edge domain on magnetization reversal to be by spin-transfer torque.

核燃料サイクルの推進と核不拡散・核セキュリティの確保

玉井 広史; 持地 敏郎; 千崎 雅生*; 岩本 友則*; 石黒 穣*; 北出 雄大; 佐藤 丙午*; 末廣 利恵*; 谷口 富裕*; 深澤 哲生*; et al.

第41回日本核物質管理学会年次大会会議論文集(インターネット), 4 Pages, 2020/11

近年、我が国のプルトニウム利用の停滞及び核燃料サイクルの核不拡散・核セキュリティに関する批判が一部で増していることを踏まえ、核燃料サイクル政策の持続的発展に向け、こうした批判の妥当性を吟味し核不拡散・核セキュリティ上の観点からの課題等について検討した。

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

https://doi.org/10.1038/s41427-019-0135-9

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.

Antiferromagnetic NiO thickness dependent sign of the spin Hall magnetoresistance in -FeO/NiO/Pt epitaxial stacks

Dong, B.-W.*; Baldrati, L.*; Schneider, C.*; 新関 友彦*; Ramos, R.*; Ross, A.*; Cramer, J.*; 齊藤 英治; Klui, M.*

Applied Physics Letters, 114(10), p.102405_1 - 102405_5, 2019/03

https://doi.org/10.1063/1.5080766

We study the spin Hall magnetoresistance (SMR) in epitaxial -FeO/NiO(001)/Pt stacks, as a function of temperature and thickness of the antiferromagnetic insulating NiO layer. Upon increasing the thickness of NiO from 0 nm to 10 nm, we detect a sign change of the SMR in the temperature range between 10 K and 280 K. This temperature dependence of the SMR in our stacks is different compared to that of previously studied yttrium iron garnet/NiO/Pt, as we do not find any peak or sign change as a function of temperature. We explain our data by a combination of spin current reflection from both the NiO/Pt and -FeO/NiO interfaces and the thickness-dependent exchange coupling mode between the NiO and -FeO layers, comprising parallel alignment for thin NiO and perpendicular alignment for thick NiO.

水平坑道掘削に伴う掘削影響領域の調査; 幌延深地層研究施設における検討

窪田 健二*; 青柳 和平; 杉田 裕

公益社団法人物理探査学会第138回(平成30年度春季)学術講演会講演論文集, p.51 - 54, 2018/05

高レベル放射性廃棄物の地層処分場建設に際しては、坑道掘削に伴う応力再配分により掘削影響領域が発生する。この領域は、廃棄体埋設後の核種の選択的な移行経路になることが想定されるため、掘削時および掘削後の挙動の理解が重要となる。本研究では、幌延深地層研究センターの深度140mおよび250mの調査坑道において実施した原位置試験結果について述べる。各深度の調査坑道における試験結果を比較したところ、掘削により割れ目が発達していた領域は、140m調査坑道で壁面から0.45m, 250m調査坑道で壁面から1.0mであった。一方、不飽和領域の発達は、140m調査坑道で壁面から1.0mであったのに対し、250m調査坑道ではほとんど発生していなかった。

Screening of cesium-accumulating mutant of radioresistant bacterium by ion beam breeding technology

佐藤 勝也; 上田 涼史郎*; 長谷 純宏; 鳴海 一成*; 大野 豊

JAEA-Review 2015-022, JAEA Takasaki Annual Report 2014, P. 100, 2016/02

https://doi.org/10.11484/jaea-review-2015-022

Bioremediation uses biological organisms to solve an environmental problem. However, microorganisms are sometimes not enough effective to achieve efficient recovery. Therefore, enhancing the functionality of microorganisms is needed to promote the active use of bioremediation. This study began with the purpose of development of Cs-accumulating bacteria by ion beam breeding technology. Previously, we suggested that is the most suitable species for the development of high Cs-accumulating bacteria by ion beam breeding technology. Candidates of Cs-accumulating mutant were screened from the mutagenized cells by ion beam breeding technology on the basis of the luminescent intensity and the cell area as indicators of intracellular Cs level and cell growth, respectively. As a result, we obtained 33 candidates, whose Cs-accumulating abilities were over 2-fold higher than that of the wild-type, from the population of mutagenized cells.

イオンビーム育種技術による植物・微生物のセシウム吸収特性の改変

大野 豊; 長谷 純宏; 佐藤 勝也; 野澤 樹; 鳴海 一成*

放射線と産業, (138), p.17 - 20, 2015/06

イオンビーム育種技術は、近年植物や微生物の改変に活発に利用され、有用品種の作出に成果をあげている。東京電力福島第一原子力発電所の事故対応のためにイオンビーム育種でなにができるのか。日本原子力研究開発機構量子ビーム応用センターでは、高崎量子応用研究所のサイクロトロンを利用し、セシウム高・低吸収植物やセシウム高濃縮菌の開発に取り組み、変異体の候補を得ることに成功した。

Molecular analysis of polyphosphate biosynthesis-related genes in

上田 涼史郎; 佐藤 勝也; 林 秀謙*; 鳴海 一成*; 大野 豊

JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 118, 2015/03

https://jopss.jaea.go.jp/pdfdata/JAEA-Review-2014-050.pdf#page=150

It is suggesting a possibility that the polyphosphate granules in cells could accumulate harmful metal ions such as radiocesium to protect the cells from cytotoxicity. has been considered as a microorganism for bioremediation under highly radioactive contaminated environments. We generated the polyphosphate biosynthesis-related genes ( and ) disruptant strains and characterized their disruption effect to clarify the role of polyphosphate for the accumulation of cesium in . The intracellular levels of polyphosphates in the disruptant and overexpressing strains were almost same and slightly increased, respectively. On other hand, the intracellular level of polyphosphates significantly increased in the disruptant strains, suggesting that the gene plays an important role in the accumulation of polyphosphate in .

純水の高温領域における抵抗率変化特性の測定

山中 晴彦; 前島 哲也; 照沼 勇斗; 渡邊 和弘; 柏木 美恵子; 花田 磨砂也

JAEA-Technology 2014-037, 12 Pages, 2014/12

JAEA-Technology-2014-037.pdf:4.27MB

国際熱核融合実験炉の中核加熱装置である中性粒子入射装置で使用する25Cから高温領域の180Cまでの温度範囲における純水の抵抗率を測定した。抵抗率は温度とともに減少するが、100C以上では、純度が異なる9M・cmの純水と5M・cmの純水でもほぼ同じ値で低下することが分かった。180Cにおける抵抗率は0.36M・cmであり、この値は理論純水の計算値と良い一致を示すことを確認した。