Spin excitations of nanometric cylindrical dots in vortex and saturated magnetic states

The magnetic normal modes of nanometric magnetic disks are calculated using a recently developed, hybrid micromagnetic method. The method is based on the subdivision of a particle into small cells and the development of a ``dynamical matrix'' that contains the restoring torques acting on the magnetization of each cell. The method includes dipolar, Zeeman, and exchange interactions. The results of these calculations are used to interpret the spin wave spectra measured by Brillouin scattering in an array of nanometric Permalloy™ disks over a wide range of applied fields encompassing both the vortex and saturated states.