Designing materials for plasmonic systems

TL;DR

This study uses advanced electronic structure calculations to identify alkali-noble intermetallics, especially KAu, as promising plasmonic materials with superior damping properties but limited plasma frequency for practical applications.

Contribution

The paper introduces a computational approach combining density functional theory and perturbation theory to evaluate and identify new plasmonic materials among alkali-noble intermetallics.

Findings

KAu outperforms gold and silver in damping frequency

KAu has a high optical gap to plasma frequency ratio

Low plasma frequency limits practical plasmonic applications

Abstract

We use electronic structure calculations based upon density functional theory to search for ideal plasmonic materials among the alkali noble intermetallics. Importantly, we use density functional perturbation theory to calculate the electron-phonon interaction and from there use a first order solution to the Boltzmann equation to estimate the phenomenological damping frequency in the Drude dielectric function. We discuss the necessary electronic features of a plasmonic material and investigate the optical properties of the alkali-noble intermetallics in terms of some generic plasmonic system quality factors. We conclude that at low negative permittivities, KAu with a damping frequency of 0.0224 eV and a high optical gap to bare plasma frequency ratio, outperforms gold and to some extent silver as a plasmonic material. Unfortunately, a low plasma frequency (1.54 eV) reduces its utility in modern plasmonics applications. We also discuss, briefly, the effect of local fields on the optical properties of these materials.