Unconventional Optical Response in Engineered Au-Ag Nanostructures

TL;DR

This paper investigates the unusual optical behavior of engineered Au-Ag nanostructures, revealing a unique resonance that defies classical Mie theory and exhibits dominant scattering with minimal losses at UV frequencies.

Contribution

It uncovers an unconventional optical resonance in Au-Ag nanostructures that cannot be explained by traditional theories, highlighting new physical phenomena in engineered nanomaterials.

Findings

Resonance at about 4 eV deviates from Mie theory predictions.

Resonance is mainly due to scattering with negligible absorption.

Material exhibits minimal losses even at ultraviolet frequencies.

Abstract

This article describes the optical properties of nanostructures composed of silver particles embedded into a gold matrix. In previous studies these materials were shown to exhibit temperature dependent transitions to a highly conductive and strongly diamagnetic state. Here we describe the anomalous optical properties of these nanostructures. Most notably, these materials fail to obey Mie theory and exhibit an unconventional resonance with a maximum at about 4 eV, while the usual gold and silver localized surface plasmon resonances are suppressed. This effect implies a significant deviation from the bulk dielectric functions of gold and silver. We further resolved this resonance into its absorbance and scattering sub-parts. It is observed that the resonance is largely comprised of scattering, with negligible losses even at ultraviolet frequencies.