| 研究課題/領域番号 |
16F16362
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| 研究機関 | 大阪大学 |
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研究代表者 |
鈴木 義茂 大阪大学, 基礎工学研究科, 教授 (50344437)
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| 研究分担者 |
CHO JAEHUN 大阪大学, 基礎工学研究科, 外国人特別研究員
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| 研究期間 (年度) |
2016-11-07 – 2019-03-31
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| キーワード | voltage effects / spin wave / magnetic dynamics / skyrmions dynamics / micromagnetics |
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| 研究実績の概要 |
First, JSPS fellow has investigated electric field induced magnetic properties changes on the magnetic tunnel junction (MTJ) with perpendicular magnetic free layer. To convince our previous result, JSPS fellow has investigated other two different devices. The stack consisted of PtMn (15 nm)/CoFe (2.6 nm)/Ru (0.86 nm)/CoFeB (2.8 nm)/MgO barrier (1.2 nm)/ CoFeB (1.5 nm)/MgO capping (1.0 nm)/Ru (5 nm)/top electrode on a Si substrate/buffer layer. JSPS fellow measured voltage dependent spin wave eigenfrequencies on 65-nm-diameter CoFeB free layer sample using thermally excited ferromagnetic resonance (TE-FMR). After analyze, we determined the exchange stiffness constant(Aex) as 3.25 pJ/m and perpendicular anisotropy energy density(Ks) 1.40 mJ/m2. For the electric field modulated magnetic parameters are determined as Aex = 0.26 ± 0.04 ×10-21 J/V, and Ks = -60 +- 24 fJ/Vm.
Second, JSPS fellow has explored on the skyrmions dynamics under various external force such as gradient magnetic field, current and thermal energy. JSPS fellow confirmed Brownian motion of skyrmion via different conditions such as finite temperature, and Gilbert damping constant. And based on the Thiele’s equation, the skyrmion dynamics under external magnetic field gradient is confirmed. The skyrmion dynamics is proportionality to Gilbert damping constant and the gradient external magnetic field.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
In the research proposal of FY2017, JSPS fellow planned to investigate voltage induced magnetic properties changes on the Yttrium Iron Garnet(YIG) film. But JSPS fellow have confirmed voltage dependent magnetic properties on 65-nm-diameter magnetic tunnel junction devices using TE-FMR and performing micromagnetic simulations. JSPS fellow studied skyrmion motion instead of voltage effect on the YIG film. Now, JSPS fellow has submitted manuscript for scientific journal. And JSPS fellow investigate skyrmion dynamics under various external forces. He has published two scientific papers.
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| 今後の研究の推進方策 |
In the FY2018, JSPS fellow will focus on the skyrmion dynamics on the various external force and interaction in the two skyrmions.
Distinct purpose of proposed research in FY2018;(1) modeling of skyrmion dynamics under various external force, such as magnetic field gradient, current, thermal energy. And the investigation of motion of skyrmion using micromagnetics. (2) understanding of two skyrmion interaction.
The proposed plan; (1) The micromagnetic simulations and analyze; JSPS fellow will confirm Brownian motion of skyrmion via different conditions such as finite temperature, and Gilbert damping constant using micromagnetic simulations. Based on our theoretical studying, the skyrmion dynamics is proportionality to Gilbert damping constant and the gradient external magnetic field. Using micromagnetic simulations, JSPS fellow will confirm proportionality of skyrmion motion via Gilbert damping constant and the gradient external magnetic field with zero and finite temperature. (2) understanding of two skyrmions interaction; JSPS fellow investigate skyrmions interaction between two skyrmions. He will evaluate repulsive/attracts forces between two skyrmions. Using repulsive force of skyrmions, JSPS will design conservative join for skyrmion based Brownian device.
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