Coupled electric dipole model for a Su-Schrieffer-Heeger chain of optically resonant coreshell nanoparticles

Abstract

Coreshell nanoparticles can combine optical features of different materials in a single nanostructure, which makes them interesting for many applications from biomedicine to energy harvesting. On the other hand, periodic arrays of plasmonic nanoparticles can exhibit topological phenomena such as topological edge states. Here we study periodic chains of Si@Ag coreshell nanoparticles. For this task, we combine the hybridization of surface plasmonic modes in complex nanostructures with the coupled electric dipole formalism employed for modelling the scattering of light by periodic arrays of small plasmonic nanoparticles. We propose treating coreshell nanoparticle as several coupled electric dipoles instead of just one and show how this is a more appropriate framework to study arrays of coreshell nanoparticles, which allows to build a one-to-one connection between the resonant modes of the nanoparticles and the dispersion bands of the system. Within this formalism, we show that a Su-Schrieffer-Heeger (SSH) chain of coreshell Si@Ag nanoparticles host multiple topological edge states pinned at the resonant frequencies of the coreshell nanoparticles.