※ 半角英数字
 年 ~ 
検索結果: 213 件中 1件目~20件目を表示


Initialising ...



Initialising ...


Initialising ...


Initialising ...


Initialising ...


Initialising ...


Initialising ...


Initialising ...



Estimation of mitigation effects of sodium nanofluid for SGTR accidents in SFR

市川 健太*; 神田 大徳; 吉岡 直樹*; 荒 邦章; 斉藤 淳一; 永井 桂一

Proceedings of 26th International Conference on Nuclear Engineering (ICONE-26) (Internet), 6 Pages, 2018/07




阿部 雄太; 永井 桂一; 真家 光良*; 中野 菜都子*; 川島 裕一*; 武末 尚久*; 斉藤 淳一

第23回動力・エネルギー技術シンポジウム講演論文集(USB Flash Drive), 5 Pages, 2018/06

ナトリウム火災ではナトレックスで窒息消火させるが、消火能力の向上や純ナトリウムの安定化を目指した消火手法を考案した。もんじゅ等の高速炉やナトリウム施設の廃止では大量ナトリウム処理でのアルカリ廃液及び水素管理が課題となる。ナトリウムは電気陰性度が他の金属より小さいため高い化学的活性度である。Na$$^{+}$$を塩化カルシウムのCl$$^{-}$$とイオン結合させ、中性かつ安定な塩化ナトリウムを生成する消火/処理方法を考案した。基礎的特性(熱分析, 元素分析等)と小規模試験から、適用が期待できる結果を得た。



斉藤 淳一

日本機械学会動力エネルギーシステム部門ニュースレター, (56), p.2 - 3, 2017/09



Study on the deterioration mechanism of layered rock-salt electrodes using epitaxial thin films; Li(Ni, Co, Mn)O$$_{2}$$ and their Zr-O surface modified electrodes

阿部 真知子*; 射場 英紀*; 鈴木 耕太*; 南嶋 宏映*; 平山 雅章*; 田村 和久; 水木 純一郎*; 齋藤 智浩*; 幾原 雄一*; 菅野 了次*

Journal of Power Sources, 345, p.108 - 119, 2017/03

 パーセンタイル:100(Chemistry, Physical)

Ni, Co, Mn三元系リチウムイオン電池正極材料について、その劣化機構について、電気化学測定、X線・中性子線測定により調べた。実験の結果、Ni, Co, Mn三元系正極は、層状岩塩型構造とスピネル構造で構成されており、充放電を繰り返すと、充放電に関与しないスピネル構造が表面を覆っていくことが分かった。一方で、Zr-Oで表面をコートした材料は劣化しないことが知られており、その原因を調べた結果、層状岩塩型構造が安定に存在し続けていることが分かった。さらに、電極/溶液界面のLi濃度を上昇していることも分かった。


Gamma radiation resistance of spin Seebeck devices

Yagmur, A.*; 内田 健一*; 井原 和紀*; 井岡 郁夫; 吉川 貴史*; 小野 円佳*; 遠藤 純一*; 柏木 王明*; 中島 哲也*; 桐原 明宏*; et al.

Applied Physics Letters, 109(24), p.243902_1 - 243902_4, 2016/12

 パーセンタイル:100(Physics, Applied)



Spin hydrodynamic generation

高橋 遼*; 松尾 衛; 小野 正雄; 針井 一哉; 中堂 博之; 岡安 悟; 家田 淳一; 高橋 三郎*; 前川 禎通; 齊藤 英治

Nature Physics, 12, p.52 - 56, 2016/01

 被引用回数:24 パーセンタイル:7.93(Physics, Multidisciplinary)

Magnetohydrodynamic generation is the conversion of fluid kinetic energy into electricity. Such conversion, which has been applied to various types of electric power generation, is driven by the Lorentz force acting on charged particles and thus a magnetic field is necessary. On the other hand, recent studies of spintronics have revealed the similarity between the function of a magnetic field and that of spin-orbit interactions in condensed matter. This suggests the existence of an undiscovered route to realize the conversion of fluid dynamics into electricity without using magnetic fields. Here we show electric voltage generation from fluid dynamics free from magnetic fields; we excited liquid-metal flows in a narrow channel and observed longitudinal voltage generation in the liquid. This voltage has nothing to do with electrification or thermoelectric effects, but turned out to follow a universal scaling rule based on a spin-mediated scenario. The result shows that the observed voltage is caused by spin-current generation from a fluid motion: spin hydrodynamic generation. The observed phenomenon allows us to make mechanical spin-current and electric generators, opening a door to fluid spintronics.


Unconventional scaling and significant enhancement of the spin Seebeck effect in multilayers

Ramos, R.*; 吉川 貴史*; Aguirre, M.*; Lucas, I.*; Anad$'o$n, A.*; 小宅 教文*; 内田 健一*; 安立 裕人; 塩見 淳一郎*; Algarabel, P. A.*; et al.

Physical Review B, 92(22), p.220407_1 - 220407_5, 2015/12

 被引用回数:41 パーセンタイル:6.37(Materials Science, Multidisciplinary)

Spin Seebeck effects have been investigated in highly crystalline magnetic multilayer films. Voltage as well as power generated by the spin Seebeck effect were found to be significantly enhanced with increasing the number of layers, $$n$$. This voltage enhancement defies the simple understanding of the spin Seebeck effect and suggests that spin current flowing between the magnetic layers in the thickness direction plays an important role in the multilayer SSE systems and the observed voltage enhancement.


Barnett effect in paramagnetic states

小野 正雄; 中堂 博之; 針井 一哉; 岡安 悟; 松尾 衛; 家田 淳一; 高橋 遼*; 前川 禎通; 齊藤 英治

Physical Review B, 92(17), p.174424_1 - 174424_4, 2015/11

 被引用回数:10 パーセンタイル:36.72(Materials Science, Multidisciplinary)

We report the observation of the Barnett effect in paramagnetic states by mechanically rotating gadolinium (Gd) metal with a rotational frequency of up to 1.5 kHz above the Curie temperature. An in situ magnetic measurement setup comprising a high-speed rotational system and a fluxgate magnetic sensor was developed for the measurement. Temperature dependence of the observed magnetization follows that of paramagnetic susceptibility, indicating that any emergent magnetic field is proportional to the rotational frequency and is independent of temperature. From the proportionality constant of the emergent field, the gyromagnetic ratio of Gd is calculated to be -29 $$pm$$ 5 GHz/T. This study revisits the primordial issue of magnetism with modern technologies to shed new light on the fundamental spin-rotation coupling.


The Promising features of new nano liquid metals; Liquid sodium containing titanium nanoparticles (LSnanop)

伊丹 俊夫*; 斉藤 淳一; 荒 邦章

Metals, 5(3), p.1212 - 1240, 2015/09

 被引用回数:2 パーセンタイル:89.5(Materials Science, Multidisciplinary)



Enhancement of anomalous Nernst effects in metallic multilayers free from proximity-induced magnetism

内田 健一*; 吉川 貴史*; 関 剛斎*; 小宅 教文*; 塩見 淳一郎*; Qiu, Z.*; 高梨 弘毅*; 齊藤 英治

Physical Review B, 92(9), p.094414_1 - 094414_6, 2015/09

 被引用回数:29 パーセンタイル:10.39(Materials Science, Multidisciplinary)

The anomalous Nernst effect (ANE) has been investigated in alternately stacked multilayer films comprising paramagnetic and ferromagnetic metals. We found that the ANE is enhanced by increasing the number of the paramagnet/ferromagnet interfaces and keeping the total thickness of the films constant, and that the enhancement appears even in the absence of magnetic proximity effects; similar behavior was observed not only in Pt/Fe multilayers but also in Au/Fe and Cu/Fe multilayers free from proximity ferromagnetism. This universal enhancement of the ANE in metallic multilayers suggests the presence of unconventional interface-induced thermoelectric conversion in the Fe films attached to the paramagnets.


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:16 パーセンタイル:22.39(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.


Line splitting by mechanical rotation in nuclear magnetic resonance

針井 一哉; 中堂 博之; 小野 正雄; 松尾 衛; 家田 淳一; 岡安 悟; 前川 禎通; 齊藤 英治

Japanese Journal of Applied Physics, 54(5), p.050302_1 - 050302_3, 2015/05

 被引用回数:5 パーセンタイル:60.55(Physics, Applied)

Nuclear magnetic resonance (NMR) measurements for a nuclear spin 1/2 system in an external magnet field and mechanical rotation in kHz range are reported. NMR signals are measured by the synchronous rotation of a sample and a detector coil under the condition that the rotation axis is perpendicular to the external field. NMR line splits into two despite the system having a single Zeeman level separation. We analytically show that the splitting originates in the nuclear spin motion under mechanical rotation, and is determined by only the angular velocity of the rotation without any material parameters.


Rotational Doppler effect and Barnett field in spinning NMR

中堂 博之; 針井 一哉; 松尾 衛; 家田 淳一; 小野 正雄; 前川 禎通; 齊藤 英治

Journal of the Physical Society of Japan, 84(4), p.043601_1 - 043601_4, 2015/04

 被引用回数:9 パーセンタイル:28.51(Physics, Multidisciplinary)

We report the observation of the rotational Doppler effect using nuclear magnetic resonance (NMR). We have developed a coil-spinning technique that enables measurements by rotating a detector and fixing a sample. We found that the rotational Doppler effect gives rise to NMR frequency shifts equal to the rotation frequency. We formulate the rotational Doppler effect and the Barnett field using a vector model for the nuclear magnetic moment. This formulation reveals that, with just the sample rotating, both effects cancel each other, thereby explaining the absence of an NMR frequency shift in conventional sample-spinning NMR measurements.


Generation of spin currents in the skyrmion phase of a helimagnetic insulator Cu$$_2$$OSeO$$_3$$

廣部 大地*; 塩見 雄毅*; 嶋田 裕樹*; 大江 純一郎*; 齊藤 英治

Journal of Applied Physics, 117(5), p.053904_1 - 053904_6, 2015/02

 被引用回数:6 パーセンタイル:54.42(Physics, Applied)

We report spin-current generation related to skyrmion dynamics resonantly excited by a microwave in a helimagnetic insulator Cu$$_2$$OSeO$$_3$$. A Pt layer was fabricated on Cu$$_2$$OSeO$$_3$$ and voltage in the Pt layer was measured upon magnetic resonance of Cu$$_2$$OSeO$$_3$$ to electrically detect injected spin currents via the inverse spin Hall effect (ISHE) in Pt. We found that ISHE-induced electromotive forces appear in the skyrmion phase of Cu$$_2$$OSeO$$_3$$ as well as in the ferrimagnetic phase, which shows that magnetic skyrmions can contribute to the spin pumping effect.


Quantitative temperature dependence of longitudinal spin Seebeck effect at high temperatures

内田 健一*; 吉川 貴史*; 三浦 飛鳥*; 塩見 淳一郎*; 齊藤 英治

Physical Review X, 4(4), p.041023_1 - 041023_9, 2014/11

 被引用回数:55 パーセンタイル:4.42(Physics, Multidisciplinary)

We report temperature-dependent measurements of longitudinal spin Seebeck effects (LSSEs) in Pt/Y$$_{3}$$Fe$$_{5}$$O$$_{12}$$ (YIG)/Pt systems in a high temperature range from room temperature to above the Curie temperature of YIG. The experimental results show that the magnitude of the LSSE voltage in the Pt/YIG/Pt systems rapidly decreases with increasing the temperature and disappears above the Curie temperature. The critical exponent of the LSSE voltage in the Pt/YIG/Pt systems at the Curie temperature is estimated to be 3, which is much greater than that for the magnetization curve of YIG. This difference highlights the fact that the mechanism of the LSSE cannot be explained in terms of simple static magnetic properties in YIG.


Characterization and storage of radioactive zeolite waste

山岸 功; 永石 隆二; 加藤 千明; 森田 圭介; 寺田 敦彦; 上地 優; 日野 竜太郎; 佐藤 博之; 西原 健司; 津幡 靖宏; et al.

Journal of Nuclear Science and Technology, 51(7-8), p.1044 - 1053, 2014/07

 被引用回数:4 パーセンタイル:51.53(Nuclear Science & Technology)



Observation of Barnett fields in solids by nuclear magnetic resonance

中堂 博之; 小野 正雄; 針井 一哉; 松尾 衛; 家田 淳一; 春木 理恵*; 岡安 悟; 前川 禎通; 安岡 弘志; 齊藤 英治

Applied Physics Express, 7(6), p.063004_1 - 063004_4, 2014/06

 被引用回数:21 パーセンタイル:20.35(Physics, Applied)



Spin current; Experimental and theoretical aspects

前川 禎通; 安立 裕人; 内田 健一*; 家田 淳一; 齊藤 英治

Journal of the Physical Society of Japan, 82(10), p.102002_1 - 102002_23, 2013/10

 被引用回数:55 パーセンタイル:19.05(Physics, Multidisciplinary)

The flow of electron spin, the so-called "spin current", is a key concept in the recent progress in spintronics. When the spin current interacts with the magnetic moment in a ferromagnetic metal, the angular momentum and energy conservations give rise to the spin transfer torque and spin-motive force, respectively. When it is injected into a non-magnetic metal attached to a ferromagnet, the electric current is induced through the spin-charge conversion mechanism (inverse spin Hall effect). The generation and manipulation of the spin current and a variety of novel phenomena given by the spin current, including the spin Seebeck effect and spin-motive force, are discussed.


Unidirectional spin-wave heat conveyer

安 東秀*; Vasyuchka, V. I.*; 内田 健一*; Chumak, A. V.*; 山口 和也*; 針井 一哉; 大江 純一郎*; Jungfleisch, M. B.*; 梶原 瑛祐*; 安立 裕人; et al.

Nature Materials, 12(6), p.549 - 553, 2013/06

 被引用回数:71 パーセンタイル:3.93(Chemistry, Physical)

In this paper, we show a magnetically controllable heat flow caused by a spin-wave current. The direction of the flow can be switched by applying a magnetic field. When microwave energy is applied to a region of ferrimagnetic Y$$_{3}$$Fe$$_{5}$$O$$_{12}$$, an end of the magnet far from this region is found to be heated in a controlled manner and a negative temperature gradient towards it is formed. This is due to unidirectional energy transfer by the excitation of spin-wave modes without time-reversal symmetry and to the conversion of spin waves into heat. The magnetically controlled remote heating we observe is directly applicable to the fabrication of a heat-flow controller.


Effects of mechanical rotation and vibration on spin currents

松尾 衛; 家田 淳一; 前川 禎通; 齊藤 英治

Journal of the Korean Physical Society, 62(10), p.1404 - 1409, 2013/05

 被引用回数:2 パーセンタイル:73.65(Physics, Multidisciplinary)


213 件中 1件目~20件目を表示