Séminaire

Vendredi 18 Novembre 2016 à 11h00.

Metal nanostructures for photonics and magneto-plasmonics

''The structure and properties (optical, magnetic, catalytic) of metallic nanostructures are very interesting from a fundamental point of view and promising for technological applications in different fields. In this seminar, I will present recent and new results of two studies carried out in the last few years on this subject. The first focuses on the experimental investigation, based on x-ray absorption spectroscopy (XAS and high-resolution x-ray fluorescence detection), on the very early steps of metal nucleation in Er-doped glasses, as induced by the metal doping process and/or intentionally promoted by specific annealing treatments. It is shown that subnanometer metal aggregates, absorbing light in a broad band of frequencies can transfer part of the absorbed energy to rare earth ions nearby, determining an increase of the rare-earth excitation cross section of some orders of magnitudes, crucial for optical communications. The effect of the cluster size, composition and cluster-matrix interaction on the optical properties and in particular on the cluster to rare-earth energy transfer will be discussed [1-4]. The second is an ongoing project, related with the emerging field of magnetoplasmonics. In this field, fabrication of nanostructured binary alloys of one plasmonic metal with a ferromagnetic one is very promising to control the optical (plasmonic) properties with a magnetic field, with posible application as optical biosensors. I will report on Au-Co binary alloy thin films prepared by room temperature co-sputtering deposition. XAS and X-ray magnetic Circular Dichroism experiment show that the high degree of mixing of the two metals induces a net magnetic moment in Au atoms, significantly higher than in the case of Au-Co multilayers. This, coupled with the possibility of further nanostructuring, makes the material very promising for magnetoplasmonic applications [5]. [1] C. Maurizio, T. Cesca, G. Perotto, B. Kalinic, N. Michieli, C. Scian, Y. Joly, G. Battaglin, P. Mazzoldi, G. Mattei, ‘Core–shell-like Au sub-nanometer clusters in Er-implanted silica’ Nanoscale 7 (2015) 8968-8977. [2] T. Cesca, B. Kalinic, N. Michieli, C. Maurizio, A. Trapananti, C. Scian, G. Battaglin, P. Mazzoldi, G. Mattei, ‘Au–Ag nanoalloy molecule-like clusters for enhanced quantum efficiency emission of Er3+ ions in silica’, Phys. Chem. Chem. Phys. 17 (2015) 28262. [3] C. Maurizio, E. Trave, G. Perotto, V. Bello, D. Pasqualini, P. Mazzoldi, G. Battaglin, T. Cesca, C. Scian, and G. Mattei, ‘Enhancement of the Er3+ luminescence by few-atom metal aggregates’, Phys. Rev. B, 83 (2011) 195430. [4] C. Maurizio, A. Quaranta, E. Ghibaudo, F. D’Acapito, J.-E. Broquin, ‘Ag site in Ag-for- Na ion-exchanged borosilicate and germanate glass waveguides’ J. Phys. Chem. C 113 (2009) 8930-8937. [5] C. Maurizio et al, submitted (2016).''