3D Multiscale Unconditionally Stable Time-Domain Modeling of Nonlinear RF Thin Film Magnetic Devices

An unconditionally stable three-dimensional (3D) finite-difference time-domain (FDTD) algorithm has been proposed to solve simultaneously Maxwell's equations and the Landau-Lifshitz-Gilbert (LLG) equation with full nonlinear effects. The proposed algorithm can predict the dynamic interaction between magnetic spins and EM fields. The accuracy of the modeling has been validated by 1. Small signal simulation of a linear ferrite isolator and 2. Large signal simulation of the dispersive permeability of a continuous ferrite film. The simulations agree with the theoretical and experimental predictions, under both linear and nonlinear circumstances. Specifically, the algorithm has fully revealed that sufficiently large RF power can decrease the ferromagnetic resonance (FMR) frequency and suppress the permeability.