Normal modes description of nonlinear ferromagnetic resonance for magnetic nanodots

The spatially-inhomogeneous magnetization dynamics in a cylindrical magnetic nanodot driven by ac spin-torque is analyzed. To this end, the Landau-Lifshitz-Gilbert-Slonczewski equation is reformulated as a system of coupled nonlinear ordinary differential equations which describe the time-evolution of normal modes amplitudes. This approach provides a class of models with reduced number of degrees of freedom and incremental accuracy between macrospin and full micromagnetics. By using this approach, the onset of foldover effect for fundamental and higher-order modes is demonstrated. The results are confirmed by full micromagnetic simulations. (c) 2022 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). https://doi.org/10.1063/9.0000327

Automated summary

The spatially-inhomogeneous magnetization dynamics in a cylindrical magnetic nanodot driven by ac spin-torque is analyzed. The Landau-Lifshitz-Gilbert-Slonczewski equation is reformulated as a system of coupled nonlinear ordinary differential equations describing the time-evolution of normal modes amplitudes. This approach provides a class of models with reduced degrees of freedom and incremental accuracy between macrospin and full micromagnetics.