Plasmon excitations in mixed metallic nanoarrays

TL;DR

This paper investigates how the plasmonic properties of mixed metallic nanoarrays can be tuned by geometry and chemistry, revealing mechanisms for broadband absorption and effects of transition metal mixing, using advanced quantum simulations.

Contribution

It provides new insights into tuning plasmon resonances in atomic chain arrays through geometry and composition, with practical guidelines for designing nano-optical devices.

Findings

Plasmon resonance position can be tuned and split into multiple peaks.

Mixing transition metals can significantly attenuate plasmonic behavior.

Interactions between electron-hole and collective excitations explain observed phenomena.

Abstract

We study the plasmonic properties of arrays of atomic chains which comprise noble (Cu, Ag, and Au) and transition (Pd, Pt) metal atoms using time-dependent density-functional theory. We show that the response to the electromagnetic radiation is related to both physics, the geometry-dependent confinement of sp-valence electrons, and chemistry, the energy position of d-electrons in the different atomic species and the hybridization between d and sp electrons. As a result it is possible to tune the position of the surface plasmon resonance, split it to several peaks, and eventually achieve broadband absorption of radiation. Mixing the arrays with transition metals can strongly attenuate the plasmonic behaviour. We analyze the origin of these phenomena and show that they arise from rich interactions between single-particle electron-hole and collective electron excitations. The tunability of the plasmonic response of arrays of atomic chains, which can be realized on solid surfaces, opens wide possibilities for their applications. In the present study we obtain guidelines how the desired properties can be achieved.