3D unconditionally stable FDTD modeling of micromagnetics and electrodynamics

A rigorous yet computationally efficient three-dimensional numerical method has been proposed based on modified alternating-direction-implicit (ADI) finite difference time domain methods (FDTD) and it has the capability of modeling the eccentric property of magnetic material being anisotropic, dispersive or nonlinear. The proposed algorithm solves Maxwell's equations and LLG equations simultaneously, requiring only tridiagonal matrix inversion as in ADI FDTD. The accuracy of the modeling has been validated by the simulated dispersive permeability of a continuous ferrite film with a 1.5 μm-thickness, using a time-step size 10
⁴
times larger than the Courant limit. The permeability agrees with the theoretical prediction and magneto-static spin wave modes are observed. Moreover, electric current sheet radiators close to perfect electrical conductors loaded with 2 μm-thick ferrite films are simulated, which exhibit a radiation efficiency 20dB higher than conventional dipole antennas on the same scale.