Effective properties of a two-dimensional magnonic metamaterial -- Conferenza internazionale

In this paper the metamaterial properties of a two-dimensional magnonic crystal are studied. The system is composed by holes embedded into a Permalloy ferromagnetic film. Both the periodicity of the magnonic crystal and the diameter of the holes are in the nanometric range. Since holes are much smaller than the characteristic mode wavelength commensurable with the periodicity, the dynamics is described in terms of effective quantities. Due to this condition also the characteristic wavelength is defined as an effective wavelength. It is shown that the effective wavelength is not necessarily equal to the well-known Bloch wavelength, because of the finite size of the holes.