"Normal Modes of Spin Excitations in Magnetic Nano-Particles"
M. Grimsditch, G. K. Leaf, H. G. Kaper, D. A. Karpeev, R. E. Camley
Preprint Version: [pdf]
This article describes a technique to compute magnetic normal modes of nano-sized particles. The technique is based on the Landau-Lifshitz formalism of micromagnetics and accounts fully for both the exchange and the dipolar field. It requires no more than the specification of the material parameters and the geometry of the sample; in particular, it does not require the specification of boundary conditions. It also allows the large-amplitude nonlinear regime to be probed. The technique is applied to a model of a polycrystalline iron particle, which is shown to possess a rich variety of normal modes. Some of these modes are reminiscent of standing waves while others are more or less localized in parts of the sample. The variation of the mode frequencies with the applied field is analyzed and compared with existing approximations.