Addressing the Influence of Localized Plasmon Resonance on the Magneto-Optical Properties of Cobalt Ferrite Nanoparticles

Year: 2019

Authors: Campo G., Pineider F., Fantechi E., Innocenti C., Caneschi A., Fernandez CD.

Autors Affiliation: Univ Firenze, INSTM, I-50019 Sesto Fiorentino, Italy; Univ Firenze, Dipartimento Chim U Schiff, I-50019 Sesto Fiorentino, Italy: CNR, INO, I-50019 Sesto Fiorentino, Italy; European Lab Nonlinear Spect LENS, I-50019 Sesto Fiorentino, Italy; Univ Pisa, INSTM, I-56124 Pisa, Italy;‎ Univ Pisa, Dipartimento Chim & Chim Ind, I-56124 Pisa, Italy; CNR, IMEM, I-43124 Parma, Italy

Abstract: The optical and magneto-optical (MO) properties of magneto-plasmonic nanocomposite films made up of a transparent polymer with a dispersion of cobalt ferrite (CFO) nanoparticles (NPs) and different concentrations of Au NPs are investigated. The volumetric concentrations of CFO and Au NPs, around 3%, and below 7%o respectively, are below the percolation limit, and hence the nanocomposite films constitute models for investigating the influence of the electromagnetic field generated at the surface plasmon resonance of Au NPs on the magneto-optical properties of CFO NPs. The plasmon resonance is present in these magneto-plasmonic composites, red-shifted with respect to the bare Au NPs and covering the spectral region where charge-transfer and crystal field MO transitions can be excited. Moreover, the magneto-optical hysteresis loops were measured in the whole spectral region. We observe that the hysteresis loops shape is a fingerprint of the different MO transitions of the CFO NPs. The strength of the MO peak around 750 nm, corresponding to the Crystal Field transition is damped respect to the corresponding peak of the CFO NPs. The strength of this peak evolves non-monotonically with the Au NPs concentration. On the other hand, the MO band around 550 nm, excited by Charge Transfer transitions, changes sign when Au NPs are present. In addition, a second MO contribution is observed. Our results demonstrate that the interactions between plasmon resonance and MO effects are not only determined by the stronger local electromagnetic fields at the resonance but they depend on the type MO transition that is involved in these oxides. This study helps to understand and design the magneto plasmonic nanostructures and applications, for example in biomedicine and sensing, in which random and weak dipolar interparticle interactions between plasmonic and magnetic nanostructures are present


Volume: 19 (8)      Pages from: 4946  to: 4953

More Information: We acknowledge the financial support of the EC through FP7-214107-2NANOMAGMA, the Italian MIUR through FIRB projects RBPR05JH2P Rete ItalNanoNet, RBFR10OAI0 Nanoplasmag, and Fondazione Cariplo through project “Chemical synthesis and characterization of magneto-plasmonic nanoheterostructures.”
KeyWords: Magneto-Plasmonics; Magneto-Optics; Au Nanoparticles; Cobalt Ferrite Nanoparticles; Magnetic Circular Dichroism; Interparticle Interactions; Localized Plasmon Resonance
DOI: 10.1166/jnn.2019.16799

Citations: 3
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