Large-angle analytical solution of magnetization precession in ferromagnetic resonance

Dynamics of magnetization M driven by microwave are derived analytically from the nonlinear Landau–Lifshitz–Gilbert equation. Analytical M and susceptibility are obtained self-consistently under a positive circularly polarized microwave field, , with frequency , which is perpendicular to a static field, . It is found that the orbital of M is always a cone along H. However, with increasing h the polar angle of M initially increases, then keeps 90° when in ferromagnetic resonance (FMR) mode, where is Gilbert damping constant and is gyromagnetic ratio. These effects result in a nonlinear variation of FMR signal as h increases to , where the maximum of resonance peak decreases from a steady value, linewidth increases from a decreasing trend. These analytical solutions provide a complete picture of the dynamics of M with different h and H.