Application of the Smith Chart in the Analysis of the Relaxation Properties of Magnetostatic Oscillations and Spin Waves in Ferrite Films

摘要

The relaxation properties of three main types of magnetostatic oscillations in a magnetostatic film resonator and nonlinear processes (parametric excitation of spin waves in the first and second bands in the presence of the tangential magnetization of the gallium-substituted yttrium-iron garnet film and foldover in the regime of normal magnetization) are studied in the frequency range 0.8-4.5 GHz. An original method is proposed for the determination of thresholds of the parametric excitation of spin waves using the deformations of Smith chart caused by variations in the measurement power level. The method is used in the high-accuracy analysis of the frequency dependences of threshold power in the presence of tangential magnetization in the regimes of resonances of both surface and backward volume magnetostatic waves. The frequency-field dependences of the absorption spectra of three main types of magnetostatic oscillations in the linear regime are used to determine the saturation magnetization, anisotropy fields, and unloaded Q factors of resonator at each mode and to calculate the relaxation parameters of the corresponding magnetostatic oscillations. The experimentally measured threshold pump powers are used to calculate the relaxation line widths of the parametrically excited spin waves with the aid of the improved theory of parametric processes that takes into account both cubic and uniaxial anisotropy of the film.