2017 Fiscal Year Research-status Report
Design and development of spin-torque-oscillator for microwave assisted magnetic recording
| Project/Area Number |
17K14802
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| Research Institution | National Institute for Materials Science |
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Principal Investigator |
S.Amin Hossein 国立研究開発法人物質・材料研究機構, 磁性・スピントロニクス材料研究拠点等, 主任研究員 (10621758)
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| Project Period (FY) |
2017-04-01 – 2019-03-31
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| Keywords | Magnetism / magnetic-recording / spin-torque-oscillator |
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| Outline of Annual Research Achievements |
The goal of this research is to design and develop spin-torque-oscillator (STO) that generates a large AC magnetic field with frequency above 20 GHz at a small bias current density (J) for microwave assisted magnetic recording (MAMR), the next generation of magnetic recording technology with areal density above 2 Tb/in2. I designed a novel device called all-in-plane STO consisting of in-plane magnetized spin-injection-layer (SIL) and field-generating-layer (FGL) separated by a metallic spacer such as Ag. Micromagnetic simulations showed this device can satisfy the need for MAMR if a material with small spin polarization (β), small damping factor, and small saturation magnetization (Ms) for SIL and large spin polarized material for FGL is used. The saturation magnetization of FGL has been optimized so that a large AC field and large oscillation cone angle is achieved. This designed STO geometry and materials minimizes J to let STO oscillate with frequency above 20 GHz. We have already developed the designed STO using different SIL materials such as Ni80Fe20 and Co2FeAl0.5Si0.5 Heusler alloys with different β and Ms. The microstructure of the films were studied using high resolution STEM-HAADF and we are currently analyzing oscillation performance of our novel All-In-Plane STO. The results achieved in the first year of the research proposal has been presented as an invited talk in domestic and international conferences. In addition, up-to-now a scientific journal paper is accepted.
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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
First year (FY2017) of this research has been dedicated mainly on materials and geometry design of STO that can produce a large Hac with oscillation frequency of over 20GHz in a low bias current density. This part of research is now completed and we are working on publication of the results. The research plan dedicated to FY2018 which has been experimental development of designed STO and nano-structure analysis is already started and we have developed experimentally part of the designed STO, in particular material for SIL. We have started nano structure characterization of STO as well. We are now writing the manuscripts for publication and part of the results have been presented in international and domestic conferences.
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| Strategy for Future Research Activity |
In FY2018, we continue working on development of all-in-plane STO device in which the material and geometry is already designed using advanced micromagnetic simulations. We have already started the experimental part and currently working on materials development of SIL with small spin polarization, small saturation magnetization, and small damping factor. On the other hand, FGL materials with sufficient magnetization and large spin polarization will be developed. The oscillation behavior of all-in-plane STO device will be analyzed experimentally and by micromagnetic simulations., The results will be presented in international conference (Intermag 2018) as well as domestic conferences in Japan and scientific journal papers will be published out of the obtained results.
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