Study On Ferromagnetic Resonance And Spin Excitations In Ferromagnetic Thin Film By Spin Rectification

In this dissertation, we comprehensively study ferromagnetic resonance and spin excitations in ferromagnetic thin film based on spin rectification. By changing the angle of applied magnetic field with respect to the film normal, high angular resolution spin rectification spectra for a single Permalloy micro-strip are obtained. The ferromagnetic resonance, perpendicular standing spin wave, and magnetostatic modes can be directly visualized in those mappings and the angular evolution of each resonance mode can be clearly observed. By fitting the angular evolution of each resonance peak in the mappings, the dynamic parameters of each mode and the quantized numbers of standing spin waves can be acutely determined. This dissertation comprehensively study ferromagnetic resonance and spin excitations in ferromagnetic thin film by spin rectification, is an important issue for the further development of spin devices and designing high density magnetic memories with fast recording speed. This dissertation mainly includes the following:1. Near the film normal, the angular dependent dispersion relationships of FMR and spin excitations are proposed, and the angular constrained relationship of magnetization and applied magnetic field is gotten. Then the FMR, PSSWs, and MSFVMs resonance position curves are gotten by solving the angular dependent dispersion relationships and the angular constrained relationship of magnetization and applied magnetic field. What above is the principle of angular dependent dc electrical approach.2. To prove accuracy of the angular dependent approach, we study FMR and spin excitations in single Permalloy stripe based on planar Hall effect, and get 2D color mappings of angular resolution spin rectification spectra at different frequencies. Base the equations we get above, we fit the FMR and spin excitations curves, and the agreement of the fitting results for the FMR and PSSWs with the measured curves is excellent, which allows us to identify these modes and accurately determine the values of dynamic parameters. Compared to the traditional approach for studying spin excitations, the results are self-consistent, so the angular dependent approach is correct.3. By the angular dependent approach, we study the effect of structure on ferromagnetic resonance and spin excitations by spin rectification. By fitting the measurend results of three different sample(micro-strip, dot array and a dot), we can get he values of dynamic parameters and the changes in the relationship between linewidth and applied magnetic field. Then we can get the effect of structure on the measured saturation magnetization, the boundary condition for the surface spins, and linewidth.