2016 Fiscal Year Annual Research Report
| Project/Area Number |
16F16362
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| Research Institution | Osaka University |
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Principal Investigator |
鈴木 義茂 大阪大学, 基礎工学研究科, 教授 (50344437)
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| Co-Investigator(Kenkyū-buntansha) |
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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| Project Period (FY) |
2016-11-07 – 2019-03-31
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| Keywords | Spin-wave eigenmodes / voltage effects / spin wave / magnetic dynamics |
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| Outline of Annual Research Achievements |
JSPS fellow has investigated voltage induced exchange stiffness constant (Aex) changes on the magnetic tunnel junction (MTJ) with perpendicular magnetic free layer. Perpendicular magnetic free layer of MTJ junction is prepared by collaborator. 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). First, in order to determine the magnetic parameters, micromagnetic simulation performed to determine the perpendicular magnetic anisotropy energy, Ks and the exchange stiffness constant, Aex. We determined Ks value from frequency of (1, 0) mode as 1.394 mJ/m2. The determined Aex value is 4.5 pJ/m. Based on precise analysis, the obtained value of voltage induced Aex changes is -0.20 ± 0.05 pJ/m with 1 V application on MgO layer which is 4.4 % changes when Aex is 4.5 pJ/m. In addition, the value of voltage induced Aex changes is obtained from -0.17 ± 0.04 to -0.23± 0.06 pJ/m at 1V when Aex value varying from 2.0 - 6.0 pJ/m.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
In the research proposal of FY2016, JSPS fellow planned to sample preparation and experimental measurements. But JSPS fellow have measured voltage dependent spinwave eigenfrequencies using TE-FMR and performed micromagnetic simulations to determine magnetic parameter such as Ks and Aex. And compare with experimental result of voltage dependent spinwave eigenfrequencies and simulation result of magnetic parameter dependent spinwave frequencies, JSPS fellow determined voltage effect of Aex changes. The micromagnetic simulations and analyze are distinct progress than JSPS suggested plan. Now, JSPA fellow is preparing manuscript for scientific journal.
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| Strategy for Future Research Activity |
JSPS fellow has a plan for research in the voltage induced magnetic properties changes on the Yttrium Iron Garnet Y3Fe￢5O12 (YIG) film using pump-probing method during FY2017. During continuous post doctor program, JSPS fellow will expand to the voltage induced magnetic properties on the magnetic insulator system.
Distinct purpose of proposed research in FY2017:
(1) Physical understanding of spin dynamics properties on YIG system.
(2) Investigation of voltage induced magnetic properties changes on YIG system.
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