Effective Description of Dynamical Properties of Magnetic Nanostructures - Invited talk by R. Zivieri

Ferromagnetic materials composing periodic magnetic systems can be described in terms of effective properties and can be regarded as magnetic metamaterials. It is possible to define effective quantities characterizing the ferromagnetic media and the collective mode dynamics like, for instance, an effective magnetization and an effective permeability both in a lossless and in a lossy ferromagnetic medium, an effective wavelength and an effective wave vector and, under some special conditions, an effective diamagnetic behavior of ferromagnetic periodic systems. Moreover, the band structure of different kinds of magnonic crystals can be determined. The aim of this talk is to give an overview of the recent results obtained on the study of effective properties of two-dimensional ferromagnetic nanostructures ranging from ferromagnetic films to two-dimensional periodic systems. Micromagnetic simulations and simple analytical calculations allow to extract the above described metamaterial properties. Some applications based on the effective properties for tailoring new magnetic devices are suggested.