Ferromagnetic Resonance Linewidth Measurement System About Magnetic Film At Extremely-High Frequency

With the increasing demand for portable and mobile products,wireless communication technology is developing rapidly,so our devices need to achieve higher data transmission rates,smaller transmission delays,and wider bandwidth.Therefore,the selection of devise materials becomes very important.When Moore’s law reaches a bottleneck,magnetic materials begin to emerge in microwave and millimeter bands,and both magnetic storage and magnetic sensors show great future markets.As the frequency is sold to the millimeter band,the material quality must also be improved,such as magnetic loss,radiation,anti-interference,and so on.At the same time,the performance characterization of these materials in the millimeter band has become very important.Among them,the loss of ferromagnetic materials can be expressed by the parameter of the material in the ferromagnetic resonance state.On the macro level,the ferromagnetic resonance linewidth is used to measure the magnetic loss of materials.At present,the main method to measure ferromagnetic resonance linewidth is perturbation method,including resonant cavity method,plane transmission line method,magnetic pit method,the former two are commonly used measurement methods,the resonant cavity method is mainly for powder,block material,and plane transmission line method is mainly for thin film test.At present,commercial instruments for thin-film ferromagnetic resonance line-width measurement mainly come from Europe and America,and the test frequency band is concentrated below 40 GHz.Therefore,in this thesis,based on the existing design of GCPW-VNA-FMR,by optimizing the size of Ground Coplanar waveguide,the linear width of thin film ferromagnetic resonance at the W wave is measured by the frequency extension of vector network analyzer ZVA-67.Finally,the signal processing and data fitting is realized by Labview software.The main work is as follow:1.HFSS is used to simulate the Coplanar waveguide based on sapphire substrate.After Magnetron sputtering coating,photolithography and ion beam etching,the Coplanar waveguide is ready,After testing by vector network analyzer,the performance of the self-developed Coplanar waveguide does not meet the requirements of the test system2.Based on the vector network analyzer model ZVA-67,by improving the size of the Ground Coplanar waveguide,the insertion loss of waveguide in the range of 50～67GHz is significantly reduced,and the signal is improved to a certain extent.At the same time,the two-port ZVA-67 is connected with a 20 GHz signal generator and mixer to realize the test of W band.3.Designed the field sweep and frequency sweep test program independently through Labview software,and realized the Labview program for data analysis and simple fitting by adding Origin’s nonlinear fitting sub VI.On this basis,carried out phase tuning and Fano fitting correction for the asymmetry phenomenon in the test curve.