On the Energy Dissipation in the Landau-Lifshitz-Gilbert Equation

The dynamics of magnetization near a stable equilibrium in ferromagnetic nanomagnets are examined within the Landau–Lifshitz–Gilbert (LLG) framework. For a small angle precession, the dependence of ferromagnetic resonance (FMR) frequency, the damping constant and the resulting quality factor $Q$ of the resonance on the local curvature around the free-energy minimum is systematically analyzed. Special attention is devoted to the behavior of the FMR decay time in the vicinity of bifurcation points, where the number of metastable energy minima changes and the commonly used approximation for the quality factor $Q\simeq 1\mathrm{/}2\alpha$ (where $\alpha$ denotes the Gilbert damping) fails.