Research On High-frequency Properties Characterization Techniques Of Magnetic Thin Films

With the magnetic recording industry has developped rapidly in recent years, the market requires higher and higher recording speed from magnetic storage medium. This pushes the operating frequency of devices such as MRAM to GHz. The magnetic damping processes become very important in this frequency. In order to optimize precessional magnetization switching, a systematic control of the magnetic damping parameter is of utmost importance. Therefore, the characterization techniques for magnetization dynamics are of great importance.Firstly, the thesis introduces the development of characterization techniques for magnetization dynamics. Secondly, we determine the emphasis of research is to build broadband ferromagnetic resonance system based on coplanar waveguide and vector network analyzer. The main contents of research are as follows:1. Using multiple instruments to build broadband ferromagnetic resonance system,and designing new coplanar waveguide test fixture based on electromagnetic simulation software HFSS is the most challenging work.2. Designing automatic measurement software based on Lab VIEW virtual instrument technology. Full-automation is realized by automatic control of magnetic field, reading of the VNA, storage and display of measurement data.3. Analyzing data evaluation methods of the broadband FMR system, building the relationship between S21 curve and FMR curve, and finally designing data evaluation software which contains phase shift Lorenz fitting and Fano fitting.4. Comparing the two results of Lorenz fitting and Fano fitting and analyzing the effect of the curve shape on the fitting result in practical tests. Consequently, Fano fitting shows a wider range of using.The broadband FMR system, which breaks through the fixed frequency limit of the conventional FMR, is proved to be accurate in practical use. Users can obtain the damping parameter by measuring FMR linewidth under different frequencies. In a word,this system is a powerful tool for studying magnetization dynamics.