Magnonics From Fundamentals to Applications
Spin waves (and their quanta magnons) can effectively carry and process information in magnetic nanostructures. By analogy to photonics, this research field is labelled magnonics. It comprises the study of excitation, detection, and manipulation of magnon
- PDF / 1,417,783 Bytes
- 17 Pages / 439.37 x 666.142 pts Page_size
- 28 Downloads / 331 Views
Spin Wave Band Structure in Two-Dimensional Magnonic Crystals G. Gubbiotti, S. Tacchi, M. Madami, G. Carlotti, R. Zivieri, F. Montoncello, F. Nizzoli, and L. Giovannini
Abstract We present a combined experimental and theoretical study of the spin wave band structure in two-dimensional magnonic crystals consisting of square arrays of either circular permalloy dots (disks) or antidots (holes). The spin wave dispersion has been measured by means of Brillouin light scattering spectroscopy, spanning the wave vector over several Brillouin zones in the reciprocal space of the artificial crystals. The experimental data are satisfactorily interpreted thanks to band structure calculations carried out using the dynamical matrix method. In the case of the array of disks, the frequency dispersion of the different eigenmodes in G. Gubbiotti () Sede di Perugia, c/o Dipartimento di Fisica, Istituto Officina dei Materiali del CNR (CNR-IOM), Via A. Pascoli, 06123 Perugia, Italy e-mail: [email protected] G. Gubbiotti · S. Tacchi · M. Madami · G. Carlotti CNISM-Unità di Perugia and Dipartimento di Fisica, Università di Perugia, Via Pascoli, 06123 Perugia, Italy S. Tacchi e-mail: [email protected] M. Madami e-mail: [email protected] G. Carlotti e-mail: [email protected] R. Zivieri · F. Montoncello · F. Nizzoli · L. Giovannini Dipartimento di Fisica, Università di Ferrara and CNISM, Via Saragat 1, 44122 Ferrara, Italy R. Zivieri e-mail: [email protected] F. Montoncello e-mail: [email protected] F. Nizzoli e-mail: [email protected] L. Giovannini e-mail: [email protected] S.O. Demokritov, A.N. Slavin (eds.), Magnonics, Topics in Applied Physics 125, DOI 10.1007/978-3-642-30247-3_15, © Springer-Verlag Berlin Heidelberg 2013
205
206
G. Gubbiotti et al.
any direction in the reciprocal space can be explained introducing the concept of a bidimensional effective wave vector. In the case of the antidot array, two families of propagating modes, having extended and localized character, exhibit bandgaps at Brillouin zone boundaries. The bandgap formation is discussed in terms of Bragg reflection as well as of the inhomogeneity of the internal magnetic field experienced by precessing spins.
15.1 Introduction Magnonic Crystals (MCs) constitute a new class of metamaterials with periodically modulated magnetic properties where collective spin excitations, i.e., spin waves (SWs), can propagate [1–8]. The magnonic density of states is characterized by the presence of frequency ranges where SW propagation is allowed, alternated with forbidden bandgaps. This happens in analogy to the propagation of electromagnetic (elastic) waves in artificial materials with periodically modulated dielectric constant (elastic properties), namely photonic [9] (phononic [10]) crystals. However, the wavelengths of SWs are shorter than those of light in the GHz frequency range, so that MCs offer better prospects for miniaturization of devices in the microwave range of frequencies, with the additional advantage that frequency position
Data Loading...
