Micromagnetic frequency-domain simulation methods for magnonic systems

We present efficient numerical methods for the simulation of small magnetization oscillations in three-dimensional micromagnetic systems. Magnetization dynamics is described by Landau-Lifshitz-Gilbert (LLG) equation, linearized frequency domain around a generic equilibrium configuration, and formulated special operator form that allows leveraging large-scale techniques commonly used to evaluate effective field time-domain simulations. By using this formulation, we derive algorithms compute free (i.e., spin wave eigenmodes) as well driven ac radio-frequency fields arbitrarily shaped nanomagnets. Moreover, semi-analytical perturbation based on computation reduced set eigenmodes are provided fast evaluation response absorption spectra function damping field. both finite difference element implementations demonstrate their effectiveness test case. These open possibility study magnonic systems discretized with several hundred thousand (or even millions) computational cells reasonably short time.