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Nanoscale structural analysis of Bi$$_{0.5}$$Na$$_{0.5}$$TiO$$_3$$ in high-temperature phases

米田 安宏; 野口 祐二*

Japanese Journal of Applied Physics, 60(SF), p.SFFA08_1 - SFFA08_10, 2021/11

 被引用回数:0 パーセンタイル:0(Physics, Applied)



Improved performance of wide bandwidth neutron-spin polarizer due to ferromagnetic interlayer exchange coupling

丸山 龍治; 山崎 大; 青木 裕之; 阿久津 和宏*; 花島 隆泰*; 宮田 登*; 曽山 和彦; Bigault, T.*; Saerbeck, T.*; Courtois, P.*

Journal of Applied Physics, 130(8), p.083904_1 - 083904_10, 2021/08

 被引用回数:0 パーセンタイル:0(Physics, Applied)

Ferromagnetic (FM) interlayer exchange coupling of ion-beam sputtered Fe/Ge multilayers was investigated by off-specular polarized neutron scattering measurements. We observed a monotonously growing correlation of magnetic moments in the out-of-plane direction with decreasing Ge thickness. The results of the Fe/Ge multilayers were used to invoke FM interlayer exchange coupling in a neutron polarizing supermirror in order to extend its bandwidth. Typically, the bandwidth is limited due to a Curie temperature close to room temperature of the thinnest Fe layers with less than 3 nm. We propose a modified layer sequence of the neutron polarizing supermirror, where the minimum Fe thickness was set to 3.5 nm whereas the Ge thickness was reduced. A performance test of the neutron polarizing supermirror showed that the FM interlayer exchange coupling contributed to the presence of the magnetization comparable to the bulk and resulted in a marked extension in the bandwidth.


Direct observation of the magnetic ordering process in the ferromagnetic semiconductor Ga$$_{1-x}$$Mn$$_{x}$$As via soft X-ray magnetic circular dichroism

竹田 幸治; 大矢 忍*; Pham, N. H.*; 小林 正起*; 斎藤 祐児; 山上 浩志; 田中 雅明*; 藤森 淳*

Journal of Applied Physics, 128(21), p.213902_1 - 213902_11, 2020/12

 被引用回数:1 パーセンタイル:24.67(Physics, Applied)

In order to understand the mechanism of the ferromagnetism in Ga$$_{1-x}$$Mn$$_{x}$$As ((Ga,Mn)As), we have investigated the magnetic behavior on a microscopic level through systematic temperature ($$T$$) and magnetic-field ($$H$$) dependent soft X-ray magnetic circular dichroism (XMCD) experiments at the Mn $$L_mathrm{2,3}$$ absorption edges. The $$T$$ and $$H$$ dependences of XMCD intensities have been analyzed using a model consisting of the ferromagnetic (FM), paramagnetic, and superparamagnetic (SPM) components. Intriguingly, we have found a common behavior for the ferromagnetic ordering process in (Ga,Mn)As samples with different Mn concentrations and different Curie temperature ($$T_mathrm{C}$$) values. In particular, the SPM component develops well above $$T_mathrm{C}$$, indicating that local FM regions are formed well above $$T_mathrm{C}$$. The present findings indicate that the onset of ferromagnetic ordering is triggered by local electronic states around the substitutional Mn ions. Insight into the most representative ferromagnetic semiconductor, (Ga,Mn)As, will be an important step in understanding the mechanism of ferromagnetic ordering in various ferromagnetic semiconductor families.


Nanoscale structural analysis of Bi$$_{0.5}$$Na$$_{0.5}$$TiO$$_3$$

米田 安宏; 野口 祐二*

Japanese Journal of Applied Physics, 59(SP), p.SPPA01_1 - SPPA01_7, 2020/11

 被引用回数:7 パーセンタイル:84.3(Physics, Applied)

放射光全散乱を利用してBi$$_{0.5}$$Na$$_{0.5}$$TiO$$_3$$ (BNT)のナノスケール構造解析を行った。BNTは脱分極温度が低いという問題があるものの、非鉛で優れた圧電特性を持つ物質として期待されている。脱分極はリラクサー同様の散漫的な振る舞いであるため、局所構造解析が必要である。局所構造解析によって化学量論的不均一性と構造不均一性の両方を明らかにした。特に局所構造領域においてはTiのランダムネスが構造の平均化を強く促進していることがわかった。


Development of a method for positron annihilation lifetime measurement in thin polyethylene films using a Na-22 source

山脇 正人*; 上杉 直也*; 岡 壽崇; 長澤 尚胤*; 安藤 太一*; O'Rourke, B. E.*; 小林 慶規*

Japanese Journal of Applied Physics, 59(11), p.116504_1 - 116504_5, 2020/11



Tolerance of spin-Seebeck thermoelectricity against irradiation by swift heavy ions

岡安 悟; 針井 一哉*; 小畠 雅明; 吉井 賢資; 福田 竜生; 石田 真彦*; 家田 淳一; 齊藤 英治

Journal of Applied Physics, 128(8), p.083902_1 - 083902_7, 2020/08

 被引用回数:0 パーセンタイル:0(Physics, Applied)

The ion-irradiation tolerance of thermoelectric devices based on the spin Seebeck effect (SSE) was investigated by using 320 MeV gold ion (Au$$^{24+}$$) beams modeling cumulative damages due to fission products emitted from the surface of spent nuclear fuels. For this purpose, prototypical Pt/Y$$_3$$Fe$$_5$$O$$_{12}$$/Gd$$_3$$Ga$$_5$$O$$_{12}$$ SSE elements were irradiated with varying the dose level at room temperature and measured the SSE voltage of them. We confirmed that the thermoelectric and magnetic properties of the SSE elements are not affected by the ion-irradiation up to $$10^{10}$$ ions/cm$$^2$$ fluence and that the SSE signal is extinguished around $$10^{12}$$ ions/cm$$^2$$, in which the ion tracks almost fully cover the sample surface. We also performed the hard X-ray photoemission spectroscopy (HAXPES) measurements to understand the effects at the interface of Pt/Y$$_3$$Fe$$_5$$O$$_{12}$$. The HAXPES measurements suggest that the chemical reaction that diminishes the SSE signals is enhanced with the increase of the irradiation dose. The present study demonstrates that SSE-based devices are applicable to thermoelectric generation even in harsh environments for a long time period.


Degradation prediction using displacement damage dose method for AlInGaP solar cells by changing displacement threshold energy under irradiation with low-energy electrons

奥野 泰希*; 石川 法人; 秋吉 優史*; 安藤 太一*; 春元 雅貴*; 今泉 充*

Japanese Journal of Applied Physics, 59(7), p.074001_1 - 074001_7, 2020/07

 被引用回数:0 パーセンタイル:0(Physics, Applied)



Development of microwave-assisted, laser-induced breakdown spectroscopy without a microwave cavity or waveguide

大場 正規; 宮部 昌文; 赤岡 克昭; 若井田 育夫

Japanese Journal of Applied Physics, 59(6), p.062001_1 - 062001_6, 2020/06

 被引用回数:0 パーセンタイル:0(Physics, Applied)



Acoustic ferromagnetic resonance and spin pumping induced by surface acoustic waves

Puebla, J.*; Xu, M.*; Rana, B.*; 山本 慧; 前川 禎通*; 大谷 義近*

Journal of Physics D; Applied Physics, 53(26), p.264002_1 - 264002_7, 2020/06

 被引用回数:12 パーセンタイル:93.25(Physics, Applied)

Voltage induced magnetization dynamics of magnetic thin films is a valuable tool to study anisotropic fields, exchange couplings, magnetization damping and spin pumping mechanism. A particularly well established technique is the ferromagnetic resonance (FMR) generated by the coupling of microwave photons and magneti- zation eigenmodes in the GHz range. Here we review the basic concepts of the so-called acoustic ferromagnetic resonance technique (a-FMR) induced by the coupling of surface acoustic waves (SAW) and magnetization of thin films. Interestingly, additional to the benefits of the microwave excited FMR technique, the coupling be- tween SAW and magnetization also offers fertile ground to study magnon-phonon and spin rotation couplings. We describe the in-plane magnetic field angle dependence of the a-FMR by measuring the absorption / trans- mission of SAW and the attenuation of SAW in the presence of rotational motion of the lattice, and show the consequent generation of spin current by acoustic spin pumping.


Toward technological contributions to remote operations in the decommissioning of the Fukushima Daiichi Nuclear Power Station

川端 邦明

Japanese Journal of Applied Physics, 59(5), p.050501_1 - 050501_9, 2020/05

 被引用回数:3 パーセンタイル:27.8(Physics, Applied)



Strong flux pinning by columnar defects with directionally dependent morphologies in GdBCO-coated conductors irradiated with 80 MeV Xe ions

末吉 哲郎*; 上滝 哲也*; 古木 裕一*; 藤吉 孝則*; 千星 聡*; 尾崎 壽紀*; 坂根 仁*; 工藤 昌輝*; 安田 和弘*; 石川 法人

Japanese Journal of Applied Physics, 59(2), p.023001_1 - 023001_7, 2020/02

 被引用回数:3 パーセンタイル:58.93(Physics, Applied)

GdBa$$_{2}$$Cu$$_{3}$$Oy (GdBCO)コート超伝導体に対して、80MeV Xeイオンを異なる方向から照射することにより、異なる方向の柱状欠陥を一つの試料に対して導入した。その結果、45$$^{circ}$$方向から照射することで導入される柱状欠陥は連続形状でかつ直径が大きく、一方でc軸方向(0$$^{circ}$$方向)から照射することで導入される柱状欠陥は不連続形状でかつ直径が小さい、ということが分かった。柱状欠陥の形態が導入方向に依存することを利用すると、臨界電流密度を効果的に向上させることができる、ということが分かった。


TEM analysis of ion-tracks and hillocks produced by swift heavy ions of different velocities in Y$$_{3}$$Fe$$_{5}$$O$$_{12}$$

石川 法人; 田口 富嗣*; 喜多村 茜; Szenes, G.*; Toimil-Molares, M. E.*; Trautmann, C.*

Journal of Applied Physics, 127(5), p.055902_1 - 055902_7, 2020/02

 被引用回数:4 パーセンタイル:68.88(Physics, Applied)



Anomalous solution softening by unique energy balance mediated by kink mechanism in tungsten-rhenium alloys

都留 智仁; 譯田 真人*; 鈴土 知明; 板倉 充洋; 尾方 成信*

Journal of Applied Physics, 127(2), p.025101_1 - 025101_9, 2020/01

 被引用回数:1 パーセンタイル:24.67(Physics, Applied)



Short- and middle-ranges order structures of KNbO$$_3$$ nanocrystals

米田 安宏; 國定 諒一*; 近田 司*; 上野 慎太郎*; 藤井 一郎*; 永田 肇*; 尾原 幸治*; 和田 智志*

Japanese Journal of Applied Physics, 58(SL), p.SLLA03_1 - SLLA03_7, 2019/11

 被引用回数:2 パーセンタイル:22.92(Physics, Applied)

We studied KNbO$$_3$$ nanocrystals grown by a solvothermal method. Average and local structures were refined by combining Rietveld and PDF analysis. We found that a rhombohedrally distorted NbO$$_6$$ octahedron was maintained in short-range order region, even in the nanocrystals with a cubic average structure. The cubic structure of KNbO$$_3$$ nanocrystals were observed as a disordered phase of the rhombohedral structure. The disordered feature can be understood that the structural transformation owing to the particle-size effect is analogous to the temperature-driven phase transition.


Modeling of yield estimation for DNA strand breaks based on Monte Carlo simulations of electron track structure in liquid water

松谷 悠佑; 甲斐 健師; 吉井 勇治*; 谷内 淑恵*; 内城 信吾*; 伊達 広行*; 佐藤 達彦

Journal of Applied Physics, 126(12), p.124701_1 - 124701_8, 2019/09

 被引用回数:10 パーセンタイル:74.82(Physics, Applied)



Spin rotation, glassy state, and magnetization switching in ${it R}$CrO$$_{3}$$ (${it R}$=La$$_{1-x}$$Pr$$_{x}$$, Gd, and Tm); Reinvestigation of magnetization reversal

吉井 賢資

Journal of Applied Physics, 126(12), p.123904_1 - 123904_8, 2019/09

 被引用回数:5 パーセンタイル:51.19(Physics, Applied)



Effect of hydrogen on chemical vapor deposition growth of graphene on Au substrates

寺澤 知潮; 平良 隆信*; 保田 諭; 小幡 誠司*; 斉木 幸一朗*; 朝岡 秀人

Japanese Journal of Applied Physics, 58(SI), p.SIIB17_1 - SIIB17_6, 2019/08

 被引用回数:0 パーセンタイル:0(Physics, Applied)



Neutron diffraction study on martensitic transformation under compressive stress in an ordered Fe$$_{3}$$Pt

福田 隆*; 山口 貴司*; 掛下 知行*; Harjo, S.; 中本 建志*

Journal of Applied Physics, 126(2), p.025107_1 - 025107_6, 2019/07


 被引用回数:1 パーセンタイル:10.83(Physics, Applied)

We have studied the structure change of an ordered Fe$$_{3}$$Pt (degree of order $$sim$$0.75) under a compressive stress applied in the [001] direction by neutron diffraction. In the absence of the stress, the alloy exhibits a weak first order martensitic transformation at 90 K from the L1$$_{2}$$-type cubic structure to the L6$$_{0}$$-type tetragonal structure. Under the compressive stress of 100 MPa, the first order nature of the thermally-induced martensitic transformation was undetectable in the temperature range of between 70 K and 270 K. The first order nature of the stress-induced martensitic transformation was also undetectable in the stress range of between 6 MPa and 300 MPa when tested at 120 K and higher temperatures. Under these conditions, the lattice parameters change continuously both in the cooling process and in the stress-applying process. A significant stress-induced softening of lattice was observed between 120 K and 265 K but not at 93 K and 295 K.


Total-reflection high-energy positron diffraction (TRHEPD) for structure determination of the topmost and immediate sub-surface atomic layers

深谷 有喜; 河裾 厚男*; 一宮 彪彦*; 兵頭 俊夫*

Journal of Physics D; Applied Physics, 52(1), p.013002_1 - 013002_19, 2019/01

 被引用回数:3 パーセンタイル:8.12(Physics, Applied)



Local structure and phase transitions of KNbO$$_3$$

米田 安宏; 尾原 幸治*; 永田 肇*

Japanese Journal of Applied Physics, 57(11S), p.11UB07_1 - 11UB07_6, 2018/11

 被引用回数:9 パーセンタイル:59.67(Physics, Applied)


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