Near-field mechanism of the enhanced broadband magneto-optical activity of hybrid Au loaded Bi:YIG.

Spiridon D Pappas,Antonio García-Martín,Burkard Hillebrands,Philipp Lang,Evangelos Th Papaioannou,Tobias Eul,Michael Hartelt,Martin Aeschlimann

doi:10.1039/d0nr00198h

Abstract

We unravel the underlying near-field mechanism of the enhancement of the magneto-optical activity of bismuth-substituted yttrium iron garnet films (Bi:YIG) loaded with gold nanoparticles. The experimental results show that the embedded gold nanoparticles lead to a broadband enhancement of the magneto-optical activity with respect to the activity of the bare Bi:YIG films. Full vectorial near- and far-field simulations demonstrate that this broadband enhancement is the result of a magneto-optically enabled cross-talking of orthogonal localized plasmon resonances. Our results pave the way to the on-demand design of the magneto-optical properties of hybrid magneto-plasmonic circuitry.

Highlights

(SEM) images of the sample reveal that the Au nanoparticles (AuNPs) are randomly distributed close to the interface between bismuth-substituted yttrium iron garnet (Bi):YIG and gadolinium gallium garnet (GGG), and that they are embedded in the Bi:YIG film
The optical properties of this sort of system are mainly determined by localized plasmon resonances (LPRs), rather than by geometrical-lattice resonances
We have experimentally demonstrated a broadband enhancement of the magneto-optical activity of hybrid Bi:YIG/AuNPs systems induced by localized plasmon resonances, by analyzing the longitudinal magneto-optical Kerr configuration

Summary

Introduction

The field of magneto-plasmonics has attracted a lot of scientific interest, both for its importance in potential technological applications, and for its fundamental scientific relevance.[1,2,3,4] Towards these directions, various ideas like using external magnetic fields to control the dispersion relation of plasmonic resonances (active magneto-plasmonics),[5] or using plasmonic resonances for spin current generation in adjacent magnetic insulators,[6,7] and the implementation of a magneto-plasmonic interferometer,[8] have been realized and explored.Magneto-optical studies on magneto-plasmonic nanostructures, composed of magnetic and/or plasmonic materials, have revealed new exciting effects: nanopatterned hybrid heterostructures,[9,10,11,12,13,14,15,16] pure ferromagnetic films,[17,18,19,20,21,22,23,24] and noble metal/magnetic dielectric systems[25,26] exhibit plasmon-induced enhancement of their magneto-optical activity. Measured magneto-optical response In Fig. 1(c) (top graphs), we present the measured reflectance spectra for both incident s- (Rss plot) and p-polarized (Rpp plot) light.

Results

Conclusion