2020 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 – 2022-03-31
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| Keywords | spintronics / magnetization dynamics / exchanged bias system |
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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 exchange biased Cr2O3/Co/Pt samples with the PMA and confirmed the blocking temperature (Tb) by MOKE measurement. To investigate the damping constant, we are conducting the ferromagnetic resonance (FMR) measurement using the PPMS-FMR, combined a Vector Network Analyzer (VNA) FMR, which enables the wide controllability of the measurement using the VNA. We measured the FMR for PMA Cr2O3/Co/Pt samples using this technique at a temperature below Tb. Based on the FMR peak shift with external magnetic fields, we could roughly evaluate the change in the effective anisotropy fields of samples with the temperature.
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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, it is difficult to detect the signal for the perpendicular magnetized systems with thin layer of FM layer. By combining the PPMS-FMR with the vector network analyzer (VNA), we could detect the FMR signal for Cr2O3/Co/Pt samples at low temperature. However, the signal became much smaller, while the noise from cable was still high when the temperature was decreased. Therefore, we faced to a problem that signal/noise ratio was small. As a result, the estimation of the damping constant became challenging even though we could evaluate the other parameters such as the effective magnetic anisotropy field, and so on.
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| Strategy for Future Research Activity |
In this research, we will overcome the challenges in the low signal/noise ratio by increasing the blocking temperature of the Cr2O3/Co/Pt samples. By doing this, the signal would be stronger in comparison with the noise from cable. Among various ways to increase the blocking temperature in the system, we will control the interface condition at the interface between Cr2O3 layer and Co layer by adding some spacer layers at the interface between Cr2O3 and Co layers. Then the PPMS-FMR combined with VNA-FMR measurement will be done for the samples to not only evaluate the effective anisotropy, but also estimate the damping constant of the systems at different temperatures.
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| Causes of Carryover |
We need to pay the fee for the sample preparation.
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