Plasmonics and Enhanced Magneto-Optics in Core−Shell Co−Ag Nanoparticles

Abstract

We present theoretical and experimental studies that explain the observed strong enhancement of the magneto-optical (MO) Faraday rotation in all-metal core-shell Co-Ag nanoparticles (NPs) attributed to localized surface plasmon resonance (LSPR). We also explain why the optical absorption and MO spectra peaks appear blue-shifted with increased Co core size while keeping the NP size constant. Further, we demonstrate direct correlation between the strong LSPR induced electromagnetic fields and the enhanced MO activity of the NPs.

Effect of chemical composition and Co-core size on the magnetic and magneto-transport properties of CoyAg100−y core–shell nanocrystallites

“…Synthesis and characterisation of magnetic core-shell nanocrystallites (CSNCs) has gained prominence due to their potential applications in diverging fields such as magnetic recording, magnetic sensing, catalysis, diagnosis, drug delivery and bio-separations [1][2][3][4][5]. The physical, chemical and magnetic properties of CSNCs can be tuned by controlling the core and shell thicknesses as well as their chemical composition [6].…”

“…Au, Ag and Cu are the three elements that are non-ferromagnetic and highly insoluble at atomic scale with Co under equilibrium conditions. Therefore, these three elements are largely chosen as shell constituents [1,2,6,8,9].…”

Magneto-optics enhancement with gain-assisted plasmonic subdiffraction chains

“…14 Localized surface plasmon excitation in MO composites containing metal nanoparticles (NPs) also promise to strongly enhance the MO response of these materials. [15][16][17][18][19][20] A different type of the MO enhancement attributed to the phenomenon of extraordinary optical transmittance was observed in systems with magnetic metallic gratings 21,22 and perforated periodic structures. [23][24][25] In this paper, we propose another approach to resonance MO enhancement.…”

Magneto-optical response in bimetallic metamaterials

“…In recent years, magnetoplasmonics, the study of systems that combine plasmonic and magnetic properties of matter, holds promise to both enhance MO effects and to enable non-reciprocal, magnetic-field-controlled plasmonic devices [2][3][4][5][6][7]. Ferromagnetic metals, such as Fe, Ni, and Co, are known to be magneto-optically active but have poor plasmonic properties in the near-infrared (NIR) spectral range due to high Joule losses.…”