Large Angle Ferromagnetic Resonance

摘要

We have studied the response of a single domain particle to continuous AC fields using analytical and numerical models based on the Landau-Lifshitz-Gilbert equation. In contrast to conventional ferromagnetic resonance studies, which operate at low power and excite only small angle oscillations of the magnetization, we are interested in high power, large angle excitations. [1] We have calculated the steady state solutions of the Landau-Lifshitz-Gilbert (LLG) equation for single domain particles with uniaxial anisotropy and a circularly polarized AC field H{sub}(ac) perpendicular to the anisotropy axis.[2] The system has only two degrees of freedom, the angle θ between the magnetization and the anisotropy axis (which determines the "orbit" of the precession of the magnetization) and the phase shift between the magnetization and the AC field. The steady state solutions are characterized by a stable orbit (i.e. the damping towards the anisotropy field is compensated by the AC field) and the magnetization processing at the frequency of the AC field. Solution of the LLG equation under these two conditions leads to the equations shown in Fig. 1.