The metamaterial properties of two-dimensional magnonic crystals (MCs) are studied according to micromagnetic and analytical calculations. Micromagnetic calculations were performed by using the Dynamical Matrix Method (DMM) extended to periodic systems [1]. The nanometric systems are composed by periodic square arrays of circular antidots (ADs) (holes) embedded into a Permalloy ferromagnetic film [2]. In the calculations the diameter of the holes varies between 10 nm and 120 nm, the array periodicity is a = 800 nm and the thickness is L = 22 nm. The geometry studied is with the external field H perpendicular to the Bloch wave vector K in the sample plane. Since holes are much smaller than the characteristic mode wavelength, the dynamics is described in terms of an effective medium approximation. This description allows us to highlight the metamaterial properties of this class of two-dimensional MCs [3]. Due to the periodicity, frequencies of collective spin modes having Damon-Eshbach-like (DE) character exhibit a band structure and the dispersion shows opening of band gaps at Brillouin zone boundaries. For each collective spin mode an effective wavelength commensurable with the array periodicity is defined. The effective wavelength is related to the scattering from the ADs of the given spin-wave mode. Holes have thus the role of point defects affecting spin dynamics. It is also shown that the effective wavelength and the associated small wave vector are not necessarily equal to their corresponding Bloch quantities. [1] L. Giovannini, F. Montoncello, and F. Nizzoli, Phys. Rev. B 75, 024416 (2007). [2] R. Zivieri, S. Tacchi, F. Montoncello, L. Giovannini, F. Nizzoli, M. Madami, G. Gubbiotti, G. Carlotti, S. Neusser, G. Duerr, and D. Grundler, Phys. Rev. B 85, 012403 (2012). [3] R. Zivieri and L. Giovannini, “Metamaterial properties of ferromagnetic antidot lattices” in press in Metamaterials.
Metamaterial Properties of Two-Dimensional Magnonic Crystals -- Presentazione poster by R. Zivieri - Conferenza nazionale
ZIVIERI, Roberto;GIOVANNINI, Loris
2013
Abstract
The metamaterial properties of two-dimensional magnonic crystals (MCs) are studied according to micromagnetic and analytical calculations. Micromagnetic calculations were performed by using the Dynamical Matrix Method (DMM) extended to periodic systems [1]. The nanometric systems are composed by periodic square arrays of circular antidots (ADs) (holes) embedded into a Permalloy ferromagnetic film [2]. In the calculations the diameter of the holes varies between 10 nm and 120 nm, the array periodicity is a = 800 nm and the thickness is L = 22 nm. The geometry studied is with the external field H perpendicular to the Bloch wave vector K in the sample plane. Since holes are much smaller than the characteristic mode wavelength, the dynamics is described in terms of an effective medium approximation. This description allows us to highlight the metamaterial properties of this class of two-dimensional MCs [3]. Due to the periodicity, frequencies of collective spin modes having Damon-Eshbach-like (DE) character exhibit a band structure and the dispersion shows opening of band gaps at Brillouin zone boundaries. For each collective spin mode an effective wavelength commensurable with the array periodicity is defined. The effective wavelength is related to the scattering from the ADs of the given spin-wave mode. Holes have thus the role of point defects affecting spin dynamics. It is also shown that the effective wavelength and the associated small wave vector are not necessarily equal to their corresponding Bloch quantities. [1] L. Giovannini, F. Montoncello, and F. Nizzoli, Phys. Rev. B 75, 024416 (2007). [2] R. Zivieri, S. Tacchi, F. Montoncello, L. Giovannini, F. Nizzoli, M. Madami, G. Gubbiotti, G. Carlotti, S. Neusser, G. Duerr, and D. Grundler, Phys. Rev. B 85, 012403 (2012). [3] R. Zivieri and L. Giovannini, “Metamaterial properties of ferromagnetic antidot lattices” in press in Metamaterials.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
