2019 Fiscal Year Research-status Report
Investigation of magnetization dynamics in exchange-biased Antiferromagnetic/Ferromagnetic/Non-magnetic (AFM/FM/NM) systems with perpendicular magnetic anisotropy
| Project/Area Number |
19K23583
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| Research Institution | Tohoku University |
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Principal Investigator |
NGUYEN THIVANANH 東北大学, 先端スピントロニクス研究開発センター, 助教 (20840101)
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| Project Period (FY) |
2019-08-30 – 2021-03-31
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| Keywords | spintronics / magnetization dynamics / high frequency meas. / antiferromagnetic |
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| Outline of Annual Research Achievements |
This study focuses on the investigation of dynamic magnetic properties in exchange-biased AFM/FM/NM systems with perpendicular magnetic anisotropy (PMA). We successfully fabricated the Cr2O3/Co/Pt samples with the PMA. For the investigation of the temperature dependence of the exchange bias, we measured the MOKE measurements. For the investigation of magnetization dynamics, we are conducting the FMR measurement using the PPMS-FMR, where the magnetic and the temperature can be controlled exactly. However, we faced to the challenges of the signal reduction for the PMA thin films, at low temperature. To overcome this, we have newly combined the PPMS-FMR with a VNA, which enables a higher sensitivity. We have successfully demonstrated this technique for Fe-Ni systems.
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| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
Using the current set up of the PPMS-FMR, the signal is only detectable for thick films. This challenges the investigation for PMA thin films. Moreover, the signal becomes much smaller by lowing the temperature. Therefore, we faced to a problem that the obtained data was sometime under/overestimated.
To overcome this, we have combined the PPMS-FMR with a VNA equipped with a CPW which enables a more reliable measurement. Even though using the current set up, we have also successfully demonstrated this technique for Fe-Ni systems. Thus, by improving this set up with a CPW with smaller width and shorter cables, or equipping the VNA-FMR with temperature-controller, the investigation of magnetization dynamics for Cr2O3/Co/Pt stack films with perpendicular magnetic anisotropy would be expected
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| Strategy for Future Research Activity |
Base on the current status, to achieve our last goals we will conduct two following steps:
Step 1: investigate the coupling between the magnetic damping constant (a) and the exchange bias (E)
Herein, we will modify the design of the CPW with thinner width, and/or equipping the VNA with temperature-controller. Thus, the relationship between (a) and (E) and temperature would be expected.
Step 2: Control the magnetization dynamics by the interfacial magnetization.
In AFM/FM/NM systems, (E) can be controlled by modifying the interfacial magnetization at the interface. This interfacial magnetization can be adjusted by adding spacer layers at the AFM/FM interface, and/or using the ferromagnetic multilayers. As a result, the magnetization dynamics in the system would be modified, correspondingly.
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| Causes of Carryover |
We need to pay the fee for revising some parts for PPMS-FMR system such as the CPW and the cables. In addition, the fee for equipping the VNA-FMR with the temperature controlling system (Peltier module) is required.
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