| Summary: | 碩士 === 國立中興大學 === 物理學系所 === 102 === Abstract
We report the ferromagnetic resonance of permalloy microstructures. We define different rod-like array microstructure patterns with permealloy film of 35 nm thickness on the GaAs substrate by e-beam lithography. For sample A, the length and the width of a rod are 1000 nm and 500 nm, respectively; the gap between rods along the long axis and the short axis are 1000 nm and 900 nm, respectively. For sample B, the length and the width of a rod are 1000 nm and 750 nm, respectively; the gap between rods along the long axis and the short axis are 600 nm and 250 nm, respectively. The outline area of the microstructure is 3 mm x 218 ?m. That patterned substrate is covered by a 100 nm SiO2 layer deposited by a plasma-enhanced chemical vapor system. Finally, the 5mm x 218 ?m microstrip was fabricated on the top of the microstructure. We also investigated the sample (sample C) with pure permealloy thin film without any pattern for reference.
We study the ferromagnetic resonance characteristics of samples by applying a microwave signal in the frequency (f) range from 1 GHz to 13 GHz and sweeping the magnetic field from -7900 Oe to +7900 Oe. The transmission signals, including magnitude and phase, are measured with a vector network analyzer (VNA). The signal strength for these samples with microstrips is significantly larger than that of devices with the permalloy structures on the top of a coplanar waveguide.
We can deduce the gyromagnetic ratio(?), the Gilbert damping parameter(?), and the Demagnetizing factor(Nx, Ny, Nz) by fitting the experimental data with Kittel''s equation. The obtained parameters of each sample are: (a) for sampl A : ? = 138.6 GHz/T、? = 0.00804、Nx = 0.184、Ny = 0.625、Nz = 0.191; (b) for sample B:?? = 208.4 GHz/T、α=0.0268、 Nx = 0.249、Ny = 0.486、Nz = 0.265; (c) for sample C: ? = 209.9 GHz/T, ??= 0.01058, Nx =0.18, Ny = 0.638, Nz = 0
|
|---|
