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Séminaire « Magnétisme et Physique du spin »

Brillouin light scattering studies of magnonic crystals - Silvia Tacchi - Mardi 8 avril 2014 à 11 h

Silvia Tacchi - Université de Pérouse
Mardi 8 avril 2014 à 11 h - INSP - 4 place Jussieu - 75252 PARIS Cedex 05 - Barre 22-32, 2e étage, salle 201

Abstract

The magnetization dynamic in ferromagnetic nanostructures such as films, multilayers, and patterned elements, both single- and multilayered, has been extensively investigated in the last decade because of the observation of new effects induced by the lateral confinement on the spin excitation spectrum. In this context, the emerging research field of magnonics whose aim is the realization of artificial structures (called magnonic crystals), where propagating spin waves are used to carry and process information, constitutes a very active field of research. Similarly to the propagation of electromagnetic waves in photonic crystals, the propagation of SWs in magnonic crystals is subject to the existence of allowed frequency ranges, alternated with forbidden band gaps.

Conventional and micro-focused Brillouin light scattering (BLS and -BLS) revealed as very powerful tools for the detection of both thermal and microwave excited SWs in such systems, thanks to the combination of wavevector resolution (BLS) and lateral resolution of about 250nm ( -BLS). From BLS measurements of the spin-wave frequencies as a function of the direction and magnitude of the in plane wavevector and of the direction and strength of the externally applied field, a determination of magnetic parameters, such as gyromagnetic ratio, saturation magnetization, anisotropy constants, and intra- and interlayer exchange constants can be attained. In this presentation some recent results obtained by our group will be presented. They will cover the study of the spin dynamics in ultrathin films, multilayer systems and patterned magnetic structures, as well as the analysis of the band diagram in magnonic crystals.