Incorporating magneto-crystalline anisotropy and damping in the autoresonance oscillations modeling in thin YIG films

Abstract

Micromagnetic modeling of non-linear autoresonance magnetization oscillations in thin films of yttrium iron garnet (YIG) with specified growth directions is conducted. It is found that in the case of rapid frequency modulation (sweep rate of the order of 1016 Hz/sec) of 1Oe excitation magnetic field, the maximum precession angle of magnetization can achieve up to 160°. For the first time, the influence of demagnetization fields, magneto-crystalline anisotropy, and Gilbert damping on autoresonance phenomena in YIG films is numerically calculated. It is shown that demagnetization fields and damping have a weak influence on parameters of autoresonance. Simultaneously, damping provides a shorter phase-locking time between the excitation field and intrinsic magnetization oscillations in the film, favoring high amplitude of magnetization oscillations. The magneto-crystalline anisotropy leads to a reduction of the threshold sweep rate of the pumping field for YIG films with [100] direction, as well as the emergence of parametric instability for [210] films. The results of the work are aimed to be applied for the experimental observation of autoresonance phenomena in thin yttrium iron garnet films.