2014 Fiscal Year Research-status Report
Study of the Dzyaloshinskii-Moriya interaction on magnetic domain wall dynamics
| Project/Area Number |
26870304
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| Research Institution | Kyoto University |
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Principal Investigator |
金 甲鎮 京都大学, 化学研究所, 助教 (40711776)
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| Project Period (FY) |
2014-04-01 – 2016-03-31
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| Keywords | quantification of DMI / DMI and domain wall |
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| Outline of Annual Research Achievements |
The final goal of this study is to elucidate the effect of the Dzyaloshinskii-Moriya interaction (DMI) on the magnetic domain wall (DW) dynamics. To achieve it, my plan in FY 2014 was to quantify the strength of the DMI by developing a novel experimental setup. The topic, which was aimed in this year, has been successfully addressed. I developed an electrical measurement system which can be exploited in the DW collision experiment. From the DW collision experiment, I proposed a novel way to quantify the strength of the DMI. Furthermore, I investigated the dynamics of DW in the presence of the DMI by changing other conditions, such as ambient temperature and layer thickness, and found that the DMI can be controlled by modulating other conditions. These results provide a novel way to quantify and to control the DMI, which is one of most urgent issue in a current spintronic research community. The outcome of this study is therefore will exert a significant impact on spintronic research community. Finally, I note that the results of this study were reported on the community by publications.
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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
Initial plan in FY2014 had two folds. One is the designing the novel experimental setup to detect the domain wall (DW) motion and the other is the performing the DW collision experiment to quantify the strength of the Dzyaloshinskii-Moriya interaction (DMI). These two sub-topics have been successfully addressed and reported by a publication. In addition to the initial plan, I performed further study to check the possibility that the strength of the DMI can be controlled by other conditions. Two experimental conditions, such as temperature and layer thickness, have been tested and found to affect the DMI. These results raise an intriguing issue on the controllability of the DMI. I reported all these results by publications during the first year of this study. I therefore think that my study was progressed more smoothly than initially planned.
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| Strategy for Future Research Activity |
The study in FY2015 will be progressed as originally planned. I will focus on the dynamic measurement of domain wall (DW) to elucidate the effect of the Dzyaloshinskii-Moriya interaction (DMI). To do it, DW motion in flow regime (fast DW motion by a high magnetic field) and creep regime (slow DW motion by a small magnetic field) will be investigated. The measurement will be performed by developing a real-time measurement technique. From the investigation, I expect that the relation between the DMI and Walker breakdown phenomenon (DW velocity breakdown at a threshold field) will be uncovered. I also expect that the dimensional transition from two to one dimension can be characterized through the DW creep measurement. In the case that the research does not progress as originally planned, I will study the relation between the DMI and DW motion in alternative way by examining the current pulse duration dependence of the DW velocity, from which we can provide a quantitative estimation of the controllability of DW in a DW-based memory device.
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| Causes of Carryover |
My initial plan was to purchase a digital oscilloscope which is essential for the study of DW dynamics. However, the amount of budget which was actually assigned was not enough to purchase the digital oscilloscope. Thus, during FY2014, I launched the project by using used oscilloscope with adding amplifiers (the budget was spent to buy amplifiers). And I decided to construct a new microscope, named as scanning magneto optical Kerr effect (s-MOKE) microscope, which can be exploited in DW dynamics study. In FY 2014, I designed the microscope that can be optimized for this study. I will construct a microscope in FY 2015 by assembling a several key components. The budget will be spent for purchasing components of s-MOKE microscope.
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| Expenditure Plan for Carryover Budget |
Incurring amount of budget will be used for purchasing components of scanning magneto optical Kerr effect (s-MOKE) microscope, which is needed for studying the relation between the Dzyaloshinskii-Moriya interaction (DMI) and the magnetic domain wall (DW) dynamics.
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