検索対象:     
報告書番号:
※ 半角英数字
 年 ~ 
 年
検索結果: 10 件中 1件目~10件目を表示
  • 1

発表形式

Initialising ...

選択項目を絞り込む

掲載資料名

Initialising ...

発表会議名

Initialising ...

筆頭著者名

Initialising ...

キーワード

Initialising ...

使用言語

Initialising ...

発行年

Initialising ...

開催年

Initialising ...

選択した検索結果をダウンロード

論文

Nonreciprocal surface acoustic wave propagation via magneto-rotation coupling

Xu, M.*; 山本 慧; Puebla, J.*; Baumgaertl, K.*; Rana, B.*; 三浦 勝哉*; 高橋 宏昌*; Grundler, D.*; 前川 禎通*; 大谷 義近*

Science Advances (Internet), 6(32), p.eabb1724_1 - eabb1724_4, 2020/08

 被引用回数:16 パーセンタイル:95.91(Multidisciplinary Sciences)

One of the most fundamental forms of magnon-phonon-interaction is an intrinsic property of magnetic materials, the "magnetoelastic coupling." This particular form of interaction has been the basis for describing magnetic materials and their strain related applications, where strain induces changes of internal magnetic fields. Different from the magnetoelastic coupling, more than 40 years ago, it was proposed that surface acoustic waves may induce surface magnons via rotational motion of the lattice in anisotropic magnets. However, a signature of this magnon-phonon coupling mechanism, termed magneto-rotation coupling, has been elusive. Here, we report the first observation and theoretical framework of the magneto-rotation coupling in a perpendicular anisotropic ultra-thin lim Ta/CoFeB/MgO, which consequently induces nonreciprocal acoustic wave attenuation with an unprecedented ratio up to 100% rectification at a theoretically predicted optimized condition. Our work not only experimentally demonstrates a fundamentally new path for investigating magnon-phonon coupling, but also justifies the feasibility of the magneto-rotation coupling based application.

論文

Unique Fermi surface and emergence of charge density wave in EuGa$$_4$$ and EuAl$$_4$$

仲村 愛*; 平仲 裕一*; 辺土 正人*; 仲間 隆男*; 三浦 泰直*; 堤 泰樹*; 森 晶宣*; 石田 一裕*; 三田村 勝哉*; 広瀬 雄介*; et al.

JPS Conference Proceedings (Internet), 3, p.011012_1 - 011012_6, 2014/06

Two europium compounds with the same structure EuGa$$_4$$ and EuAl$$_4$$ have been investigated. The Fermi surfaces revealed experimentally show a peculiar feature: flat Fermi surface sheets appear parallel to the tetragonal [110] planes. Reflecting this, a charge density wave transition due to the nesting of Fermi surface sheets has been observed in EuAl$$_4$$.

論文

Fermi surface and magnetic properties of antiferromagnet EuBi$$_3$$

仲村 愛*; 平仲 裕一*; 辺土 正人*; 仲間 隆男*; 立津 慶幸*; 眞榮平 孝裕*; 三浦 泰直*; 森 晶宣*; 堤 泰樹*; 広瀬 雄介*; et al.

Journal of the Physical Society of Japan, 82(12), p.124708_1 - 124708_6, 2013/12

 被引用回数:18 パーセンタイル:72.91(Physics, Multidisciplinary)

Fermi surfaces and magnetic properties of an antiferromagnet EuBi$$_3$$ were investigated on a flux-grown single crystal. A critical magnetic field of 225 kOe where the magnetic moments are forced to align ferromagnetically was well explained by the magnetic exchange interaction based on a two-sublattice model. The Fermi surface characteristics are in agreement with the theoretical prediction indicating a fully magnetic divalent state in Eu atoms.

論文

Magnetic and Fermi surface properties of EuGa$$_4$$

仲村 愛*; 平仲 裕一*; 辺土 正人*; 仲間 隆男*; 三浦 泰直*; 堤 泰樹*; 森 晶宣*; 石田 一裕*; 三田村 勝哉*; 広瀬 雄介*; et al.

Journal of the Physical Society of Japan, 82(10), p.104703_1 - 104703_10, 2013/10

 被引用回数:29 パーセンタイル:82(Physics, Multidisciplinary)

High quality single crystals of EuGa$$_4$$ have been grown from Ga flux. Electrical resistivity, magnetic susceptibility, high-field magnetization, specific heat, thermoelectric power and de Haas-van Alphen effect were investigated. Antiferromagnetic transition due to divalent Eu atoms were observed at 16.5 K. A charge density wave transition was also found under high pressure accompanied by a Fermi surface reconstruction. These observations were fully accounted for by the Fermi surface topology and corresponding band calculations.

論文

Reduction of intrinsic critical current density under a magnetic field along the hard axis of a free layer in a magnetic tunnel junction

三浦 勝哉*; 菅野 量子*; 市村 雅彦*; 早川 純*; 池田 正二*; 大野 英男*; 前川 禎通

Physical Review B, 84(17), p.174434_1 - 174434_7, 2011/11

 被引用回数:1 パーセンタイル:6.07(Materials Science, Multidisciplinary)

We investigated the effect of a magnetic field along a hard in-plane axis $$H$$$$_{rm hard}$$ on a current-induced magnetization switching in magnetic tunnel junctions. Our recent findings suggest that the effect of $$H$$$$_{rm hard}$$ mainly appears in the dynamic properties due to the nonconservative force of the spin-transfer torque based on the Slonczewski's model. A simple stability analysis demonstrated that the tilt of the magnetization direction away from the easy axis caused by the presence of $$H$$$$_{rm hard}$$ induces an imbalance between the spin-transfer and damping torques and that applying a current achieves the further tilted stable state. Achievement of this stable state can be interpreted as the suppression of the effect of the effective demagnetization field. Therefore the major reduction in $$J$$$$_{rm c0}$$ is due to the suppression of H$$_d^{*}$$ caused by the presence of $$H$$$$_{rm hard}$$.

口頭

MOX reprocessing at Tokai reprocessing plant

田口 克也; 長岡 真一; 山中 淳至; 佐藤 武彦; 中村 芳信; 大森 栄一; 三浦 信之

no journal, , 

東海再処理施設では、2007年3月からMOX燃料の再処理技術開発のため「ふげん」MOXタイプB使用済燃料の再処理を開始した。再処理は順調に進み、MOX燃料もウラン燃料同様に安全に処理できることを確認した。不溶解残渣の影響などMOX燃料に特徴的な知見が得られつつある。今後さらに数年にわたりMOX燃料の処理を続け、溶解特性,不溶解残渣,溶媒性能等に関する知見を蓄積していく。

口頭

Fabrication and evaluation of light-emitting SiO$$_{2}$$ substrate co-implanted with Si and C ions

菊地 秀輔*; Umenyi, A. V.*; 稲田 和紀*; 河嶋 亮広*; 野口 克也*; 佐々木 友之*; 三浦 健太*; 花泉 修*; 山本 春也; 川口 和弘; et al.

no journal, , 

これまでに、Siイオンを注入した溶融石英板(SiO$$_{2}$$)が、1150$$sim$$1250$$^{circ}$$Cのアニールによって青色発光(発光ピーク波長400nm)を示すことを初めて見いだし、特に1200$$^{circ}$$Cのアニール後にその発光ピーク強度が最大になることを実証している。しかし、1200$$^{circ}$$C前後でのアニールは非常に高温で、実際の応用を考えた場合、熱に弱い部材との集積化が難しくなり、この材料を適用できる応用デバイスの範囲が制限されてしまう。そこで今回は、より低温のアニールでも発光するSiO$$_{2}$$基板の開発を目指し、Siイオンに加えてCイオンを注入して発光特性の評価を行った。その結果、700$$^{circ}$$Cという比較的低温のアニールによっても、可視域の発光が観測できることを確認した。また、Siイオン及びCイオンの照射量の比によって、発光ピーク波長がシフトすることも確認できた。波長650nm付近の発光ピークは、Siイオン照射により発現するものと思われ、一方で波長450nm付近の発光ピークは、Cイオン照射によるものと考えられ、Siイオン及びCイオンの照射量の比によって、発光波長を制御できる可能性があることが示された。

口頭

Mach-Zehnder type thermo-optic switch fabricated by proton beam writing

小澤 優介*; 久保田 仁*; 三浦 健太*; 花泉 修*; 野口 克也*; 佐藤 隆博; 石井 保行; 江夏 昌志; 高野 勝昌*; 大久保 猛; et al.

no journal, , 

A Mach-Zehnder (MZ) type thermo-optic switch for a wavelength of 1.55 $$mu$$m was fabricated using Proton Beam Writing (PBW) in this study. The fabrication was carried out by the following processes: (1) a SiO$$_2$$ under-cladding was deposited on a Si substrate, (2) a 10-$$mu$$m-thick PMMA film was spin coated onto the SiO$$_2$$ layer as a core, (3) a MZ type waveguide with the width of 8 $$mu$$m was drawn on the PMMA film by PBW with the beam size of 1.1 $$mu$$m$$phi$$ and current of 50 pA at 1.7 MeV, (4) a PMMA film was deposited again on the sample as an upper-cladding layer, and (5) a titanium heater as a phase shifter and aluminum electrodes were formed on the sample by vacuum evaporation with UV lithography and wet etching. In the operation test of this switch, the intensity of 1.55 $$mu$$m laser light through the switch was measured by a vidicon camera at the exit side along with varying the electric power for a titanium heater (the switching power). The intensity ratio of the output lights for ON/OFF of the heater was obtained as a function of the switching power. The result showed the fabricated switch worked as an MZ type thermo-optic switch with an ON/OFF ratio of 9.0 dB on a switching power of 43.9 mW.

口頭

Photoluminescence properties of light-emitting SiO$$_{2}$$ substrates implanted with Si and C ions

稲田 和紀*; 河嶋 亮広*; 狩野 圭佑*; 野口 克也*; 三浦 健太*; 花泉 修*; 山本 春也; 川口 和弘*; 吉川 正人

no journal, , 

これまでにシリコン(Si)イオン注入により青色発光する溶融石英板(SiO$$_{2}$$)に炭素(C)をイオン注入することより、より長波長側の可視光域で発光が起こることを見いだした。そこで、Siイオン及びCイオンの注入量比の異なる試料を作製し、それらの発光ピーク波長について系統的に調べた。石英板へのイオン注入には、150keV Si(注入量: $$sim$$5.0$$times$$10$$^{16}$$ ions/cm$$^{2}$$), 75keV C(注入量: $$sim$$3.0$$times$$10$$^{16}$$ions/cm$$^{2}$$)の条件で試料にイオン注入を行い、1000$$^{circ}$$Cのアニール処理後にHe-Cd laser ($$lambda$$=325nm)によるホトルミネッセンス測定を行った。その結果、発光ピーク波長は、Si注入量に対するC注入量の比が増加すると短波長側にシフトする傾向を示した。Si及びCの注入量の比を制御することにより、発光波長を制御できる可能性があることが示された。

口頭

Fabrication of Mach-Zehnder optical waveguide structures in PDMS thin films using proton beam writing

狩野 圭佑*; 猿谷 良太*; 川端 駿介*; 新木 潤*; 野口 克也*; 加田 渉*; 三浦 健太*; 加藤 聖*; 佐藤 隆博; 江夏 昌志; et al.

no journal, , 

Proton beam writing (PBW) has been applied to fabricate Mach-Zehnder (MZ) optical waveguides which is expected to be an optical switch with small power consumption, because only one processing of PBW enables us to fabricate such waveguides even inside of plastic materials. Such waveguides were fabricated in thin poly-methyl-methacrylate (PMMA) films by PBW. However, they had low transmittance. In order to fabricate MZ optical waveguides with higher transmittance, PBW was applied to poly-dimethyl-siloxane (PDMS) with higher transparency than PMMA. Thirty-micrometer thick PDMS films formed on silicon wafers were irradiated at different beam fluences using a 750-keV proton microbeam which reaches the half depth of the entire film thickness. The single mode propagation of the fabricated optical waveguide was checked by the 1.55-$$mu$$m light. The observation results showed that the single-mode propagation was detected only for the waveguide fabricated with the fluence of 100 nC/mm$$^2$$ and that the propagated light intensity was higher than that of PMMA. The waveguide structure has been successfully fabricated in thin PDMS films by PBW.

10 件中 1件目~10件目を表示
  • 1